Electronic Schematic Diagram

One Transistor LED Flasher Circuit

2012-02-14T19:46:00.000-08:00

Here the schematic diagram of one transistor LED flasher. This circuit can be the simplest circuit led flasher over the world.... :D

This is a novel flasher circuit working with a single driver transistor that will take its flash-rate from a flashing LED. The flasher in the photo is 3mm. An ordinary LED is not going to work. The flash rate are not able to be altered by the brightness of the high-bright white LED can be adjusted by replacing the 1k resistor across the 100uF electrolytic to 4k7 or 10k.

The 1k resistor discharges the 100uF so that when the transistor turns on, the charging current into the 100uF illuminates the white LED. If a 10k discharge resistor is applied, the 100uF will not be completely discharged and also the LED isn't going to flash as bright.

All of the components within the photo are in the identical places as in the circuit diagram in making it easy to learn how the components are joined.

Magic Lights Circuit using Bi-Colour LED

2012-02-05T20:03:00.000-08:00

This is the magic lights circuit which use bi-colour LED as the output to provide the light. The circuit uses 14 bi-colour (red and green) LEDs having 3 terminals each. Various dancing colour patterns are generated utilizing this circuit considering that each LED can create three various colours. The middle terminal (pin 2) of the LEDs will be the common cathode pin that is grounded. When a positive voltage is applied to pin one, it emits red light. Similarly, when positive voltage is applied to pin 3. it emits green light. And when positive voltage is simultaneously applied to its pins 1 and 3, it emits amber light.

The circuit could be implemented for decorative lights. The IC1 (timer IC 555) is applied in astable mode of multivibrator to produce clock signal for IC2 and IC3 (CD4518) that are dual BCD counters.

The two counters of each one of these ICs have already been cascaded to acquire 8 outputs from each. The outputs from IC2 and IC3 are connected to IC4 through IC7 that are BCD to 7-segment latch/decoder/driver ICs. Therefore we acquire a complete of 14 segment outputs from each of the IC pairs composed of IC4 plus IC5 and IC6 plus IC7. While outputs from former pair are connected to pin No. 1 of all the 14 bi-colour LEDs through current limiting resistors, the ouputs of the latter pair are similarly connected to pin No.3 of all the bi-colour LEDs to acquire a magical dancing lights effect.

Simple Audio Booster

2012-01-29T19:17:00.000-08:00

This is a simple and low-cost audio booster circuit design. The circuit is based on general purpose amplifier and switches, 2N3392 transistor packed in TO-92. This circuit should be installed before power amplifier module.

To get the maximum audio performance, use metalfilm resistors, MKM and tantalum capacitors which have small tolerance of its value. Also, use stabilized and regulated 9V power supply for better result. You can simply use LM7809 IC regulator on 12V power supply to get stabilized 9V output. The 100K variable resistor is used to adjust the volume, you may remove this component and use main volume in your audio system.

Cricket Chirping Sound Generator

2012-01-24T23:00:00.000-08:00

This is the circuit diagram of cricket chirping sound generator based on IC 4060, a 14 stage ripple counter and oscillator IC. A suitable audio wave form is produced by IC2 and related electronic components, driving the mini speaker through Q1. To allow a more real-life behavior, the chirp is interrupted in a pseudo-casual way by two timers built around IC1C and IC1D, whose outputs are mixed into IC1B and further time-delayed by IC1A, driving the reset pin of IC2.

An optional Photoresistor can be wired across this pin and positive supply, it is to make the circuit operates in the dark and stops when light is coming, thus imitating the cricket's behavior even more closely. R9 acts as volume control and can be a preset trimmer or a small potentiometer.

Components List:

R1 = 330K 1/4W
R2 = 220K 1/4W
R3,R6 = 100K 1/4W
R4 = Photo resistor (Optional, see text)
R5,R7 = 22K 1/4W
R8 = 10K 1/4W
R9 = 470R 1/2W Trimmer Cermet or Carbon
R10 = 22R 1/4W
C1,C2,C3 = 47µF/25V
C4 = 10µF/25V
C5 = 1µF/50V
C6 = 10nF/63V
D1,D2,D3,D4 = 1N4148
Q1 = BC547
IC1 = 4093
IC2 = 4060
SPKR = 8 Ohm
SW1 = SPST Toggle or Slide Switch
B1 = 9V PP3 Battery (See Notes)

Circuit Notes:

The circuit can be powered by any battery or power supply adapter with 5 - 12V range.
For maximum performance results please use a loudspeaker as small as possible.
In some cases, the chirp can be improved further on by pressing the loudspeaker against a flat surface, for example. a wooden table.

Cricket chirping sound generator circuit project, page source: extremecircuits.net

19W Power Amplifier based LA4440

2012-01-21T03:47:00.000-08:00

This is the 19W power amplifier circuit built based power IC LA4440. The LA4440 output configured in bridge connection. The LA4440 can be used for stereo amplifier and it will give power output of 6W on each channel. But if you use this power IC in bridge mode, the it will deliver power audio output up to 19W. Recommended supply voltage is 13.2V, 2A and heatsink should be mounted on the power IC.

Power IC LA4440 Features:

Built-in 2 channels (dual) enabling use in stereo and bridge amplifier applications.

Dual : 6W´2 (typ.)
Bridge : 19W (typ.)

Small pop noise at the time of power supply ON/OFF and good starting balance.
Minimum number of external parts required.
Good ripple rejection : 46dB (typ.)
Easy to design radiator fin.
Low distortion over a wide range from low frequencies to high frequencies.
Small residual noise (Rg=0).
Good channel separation.
Built-in protectors.
Built-in audio muting function.

Overvoltage, surge voltage protector
Thermal protector
Pin-to-pin short protector

Download the database of LA4440

15W Audio Amplifier with STK055

2012-01-13T15:41:00.000-08:00

Here the schematic diagram of 15W audio amplifier, built based on single power chip STK055 from Sanyo.The STK055 is old power amplifier chip which still available on the market because of the ease of its usage and the performance is good. This chip requires heatsink to be mounted on its body.

Technical details:

Maximum power supply: ± 28V
Recommended supply voltage: ± 20V
Power output: 15W
RL: 8 Ohm
TDH: 0.3%
Rin: 52K
Gain: 26.4 dB
Noise: 0.3mV

Mice Repellent Circuit

2012-01-08T05:01:00.000-08:00

This is the circuit diagram of mice repellent. Mice are animals that are very annoying, because sometimes he is damaging the object stored in the form of archives that are still valuable.

To drive out the mice, you can create an electronic circuit of mice repellent as shown above. With 50KHz frequency generated by the timer IC 555. The mice would run because his ears will feel sore due to the signal frequency.

The work of this circuit is very simple. The timer IC act as the frequency generator, while the frequency value is decided by C1 and C3. The output of 555 will be amplified by the SC1162 transistor and then fed to the speaker so the audio signal can be heard by the mice.

Parts List:

R1 = 1K8
R2 = 1K
R3 = 5K6
R4 = 480R
C1 = 2,2nF
C2 = 0,022uF/6V
IC = 555
Q = SC1162
SP = Speaker 4 ohm

Surround Sound Processor Circuit

2012-01-02T14:55:00.000-08:00

This is the easy build surround sound processor circuit using the digital delay process method. This audio processor isn't applying any unique function ICs that tough to obtain parsonaly, and designed in only common purpose ICs.

The kind of this Surround Processor is producing the surround impact with processing two channels of stereo supply. The majority of those are generates the surround impact with separates reverberations from supply signal and applies any processes, after which mix it to front channels or output as rear channel.

The circuit works and contains three modules:

Separating the Reverberatins

The distinction in between each channels is separated with distinction amplifier from the op-amp. And greater frequencies inside the distinction signal are cut using the LPF.

A-D and D-A conversion

These are composed with common purpose ICs. The A-D converter is basically delta modurator that making use of a comparator plus a D type flip-flop. And it converts analog signal into digital data of one bit, 2 Msa/sec. Following passed digital delay, the bit stream is directly conversion into analog signal using the integrater.

It isn't beneficial that signal to noise ratio and distortion as this A-D, D-A converter.

Digital Delay

For the digital delay method, a DRAM chip is utilised as a FIFO memory. This circuit design demands a 64K bit DRAM, but I utilized a 256K bit DRAM discovered within the junk box. Shift register generates Read-Modify-Write cycle, read out old data and save new data in a single cycle.

And lower byte in the address counter is assined as row address with the DRAM to increment row address every single cycle, to ensure that refresh cycle is often omitted. The FIFO length is 65536 bits and 2 Msa/sec makes 33 msec of delay time.

Surround sound processor circuit source page: http://elm-chan.org/works/srp/report_e.html

Mic Preamplifier Circuit based TLC251

2011-12-25T16:13:00.000-08:00

Here the schematic diagram of mic preamplifier which build based on operational amplifier TC251. The TLC251 is operating in low bias. The circuit works with only 1.5 V supply draws electric current of only 10 mA, so the battery operation will be prefered. Circuit frequency response is 3dB, 27 Hz to 4.8 kHz.

Frequency Response:

The TLC251 are low-cost, low-power programmable operational amplifiers designed to operate with single or dual power supplies. Because the input common-mode range extends to the negative rail and the power consumption is very low, this chip is ideally suited for battery-powered or energy-conserving applications. A bias-select pin can be used to program one of three ac performance and power-dissipation levels to suit the application. The series features operation down to a 1.4V supply and is stable at unity gain.

Download the TLC251 datasheet document from the following link:
» Download link

Stereo Tube Power Amplifier Schematic

2011-12-18T21:23:00.000-08:00

This is the circuit diagram of stereo tube power amplifier. It applies 3 types of tube that are 2 6SF5 GT high-mu triodes, 1 5Y3 GT vacuum rectifier, and 2 6K6 power beam amplifiers. The Audio input can be from any two-channel line level device such as a television, CD player, or VCR. It is of the tube type, using only 5 tubes total with no more than about 45 Watts power consumption from the outlet.

Components List:
R1,R10,R13 = 2.2M Ohm Potensiometer
R2 = 470K Ohm
R3 = 1M Ohm
R4 = 220K Ohm
R5 = 330 Ohm 2W Resistor
R6 = 220K Ohm
R7 = 2.2M Ohm
R8 = 1M Ohm
R9 = 720 Ohm 20W Resistor
R11 = 33K Ohm
R12 = 22K Ohm
C1,C9 = 4nF 400V Capacitor
C2 = 50nF 600V Capacitor
C3 = 20uF/25V
C4 = 10nF 400V Capacitor
C5 = 200pF 400V Ceramic Disc Capacitor
C6,C7 = 15uF 450V Capacitor
C8 = 15uF 400V Capacitor
T1 = 117V Primary, 350VCT Secondary, 6.3V Secondary, 6.3V Secondary
T2 = 7600 Ohm Primary, 4 or 8 Ohm Secondary
SW1 = SPST Switch
SP1,SP2 = 12" or smaller, 4 or 8 ohm speakers
MISC = 5 tube sockets, 2 RCA jacks, PC board or chassis, wire, knobs, etc.

Stereo Tube Power Amplifier Circuit Notes:

C8 is for radio interference suppression and may be omitted.
The 6V6 GT tube may be substituted for the 6K6 to lower power requirements.
The 5Y3 GT tube should be mounted in a vertical position and be well ventilated. The 6K6 and 6SF5 tubes can be mounted in any position.
The power supply portion of this unit may be used for anything requiring 290-320v DC up to about 3 amperes.
Controls should have an audio taper.

Circuit Source: http://english.cxem.net/amplifier/amplifier13.php

12 LED VU Meter Circuit

2011-11-22T23:30:00.001-08:00

Here the 12 LED VU meter circuit. This is a simple visual indication of the audio level signals, adaptive to various user needs. Can be adapted to different input levels, adjustable by trimmer TR1 (state) - TR2 (Gain), then rectified by diodes D1-D2 (standard negative mark-recovery periods) and driven in the main circuit indication, consisting of the diodes D3 up to D13, transistors Q2-Q13 and materials that exist around them.

The visual indicator is taken from the series of diodes LED LD1-13. Each Led illuminates when the level changed during about 0,65 V. The power requirements are 100 ma full term. We can add as many steps we want LED, always assuming the power where you need the new LED.

Components List

R1 = 47Kohm
R2,3 = 1Mohm
R4,R7 = 1Kohm
R5 = 100ohm
R6 = 18Kohm
R9,11,13,15,17 = 560ohm
R19,21,23,25,27 = 560ohm
R29,31 = 560ohm
R8,10,12,14 = 4.7Kohm
R16,18,20,22 = 4.7Kohm
R24,26,28,30 = 4.7Kohm
C1 = 10uF/25V
C2 = 100nF/100V MKT
C3 = 4.7uF/25V

C4 = 4.7uF/25V
C5 = 10uF/25V
C6 = 47uF/25V
C7-8 = 100nF/100V
TR1 = 100Kohm Trimmer
TR2 = 4.7Kohm Trimmer
LD1 until LD7 = LED Green
LD8,LD9,LD10 = LED Yellow
LD11,LD12,LD13 = LED Red
D1 until D13 = 1N4148
Q1 until Q13 = BC550C - BC549B
IC1 = TL071
IC2 = 7812 [With Heatsink]
All Resistors is 1/4W 1 -5%

12 LED VU Meter Circuit source page: users.otenet.gr

2-Way Active Crossover Circuit

2011-11-12T02:44:00.001-08:00

This is the schematic diagram of 2-way active crossover circuit. The "active" word means that the circuit use active component and need power supply to work. Take a note that the input of this circuit is not connected to the output of power amplifier. This crossover circuit module must be placed before the amplifier circuit. The "Low Out" output connected to a power amplifier and the low speaker [Woofer], while the "High Out" output is drive the power amplifier of high speaker [Tweeter].

Parts List

R1 = 100Kohms
R2,3,4,5,6 = 37.5ohms [33K+4.7K]
R7 = 75Kohms[150K//150K
R8 = N.C
R9,10,11,12,13,14,15,16 = 10Kohms
R17,18 = 47Kohms
R19,20 = 47ohms
C1 = 4.7uF/100V MKT
C2,3,4,5,6,7,12,13 = 1nF 100V MKT
C8,9,10,11,14,15 = 100nF 100V MKT
C16 = 2.2uF/100V MKT
C17 = 470nF 100V MKT
C18,19 = 47uF/25V
J1,2,3 = 2pin conn. 2.54mm pin step
J4 = 3pin conn. 2.54mm pin step
IC1,2,3 = NE5532 , TL072
TR1 = 100Kohms trim. or pot.
TR2,3 = 47Kohms trim. or pot.
All the Resistors is 1,2% 1/4W metal film

Circuit Source: 2-Way Active Crossover Circuit with Linear Phase Response

Home Telephone FM Transmitter Circuit

2011-11-01T03:04:00.000-07:00

Here the schematic diagram of home telephone FM transmitter. This circuit connects in series with your home phone line and delivers the phone conversation through the FM band any time you pick up the telephone handset. Transmitted signal could be tuned by any FM receiver. The circuit features an "On Air" LED indicator and also gives you a switch that can be utilized to turn off the transmitter. A special characteristic of the circuit is the fact that no battery is required to operate the circuit because electrical power is taken from your phone line.

The transmitter circuit works by using only a short piece of wire aerial about 4" / 10 cm long to transmit the signal and a portion of the RF signal can also be radiated via the phone line itself. The circuit may possibly be implemented to share or record conversations, but will not be meant for illegal use.

Source: Home Telephone FM Transmitter Circuit

Stereo PLL FM Transmitter based BH1417

2011-10-26T04:39:00.000-07:00

Here the circuit diagram of stereo PLL FM transmitter based BH1417 chip. This is certainly the most recent BH1417 FM Transmitter design diagram from RHOM that consists of lots of capabilities in a single tiny package. It includes pre-emphasis, limiter to ensure that the music can be transmitted at the same audio level, stereo encoder for stereo transmission, low pass filter that blocks any audio signals above 15KHz to avoid any RF interference, PLL circuit that delivers rock solid frequency transmission (no extra frequency drift), FM oscillator and RF output buffer.

There is certainly 14 possible transmission frequencies with 200KHz increments that you can select using a 4-DIP switch. Lower band frequencies begin from 88.7 up to 89.9 MHz, and upper band frequencies begin from 107.7 up to 108.9 MHz.

BH1417 could be supplied with 4 - 6 voltage and needs only about 30mA, giving 20mW output RF power. BH1417 delivers 40dB channel separation that is fairly good, although older BA1404 FM Transmitter chip delivers slightly better 45dB channel separation.

BH1417 is only offered in SOP22 IC case so this may possibly be an inconvenience for some people. On the other hand, since the chip is smaller than common DIP-based ICs it's possible to fit the whole transmitter on a compact PCB.

BH1417 chip may possibly also be applied a stand alone stereo encoder. The benefit of that's that you have full freedom of working with a transmitter and amplifier of your choice. You will still have a pre-emphasis, limiter, stereo encoder and low pass filter in a single tiny package since very few external components are required for these blocks. PIN 5 is MPX output that could be directly connected to an external FM transmitter through a 10uF capacitor.

Detailed information about this circuit, visit: http://electronics-diy.com/BH1417_PLL_Stereo_FM_Transmitter.php . The kit of stereo PLL FM transmitter based BH1417 also available there.

FM Transmitter Circuit with MAX2606

2011-10-21T19:04:00.000-07:00

FM transmitter circuit which is build using single chip of MAX2606. A very simple FM transmitter connects your home-entertainment system to a portable radio that will be carried surrounding the house and into the back yard. As an example, it is possible to play music on the CD player in your private room, and listen to it on a portable radio by the back-yard barbeque.

IC1 is a voltage-controlled oscillator with integrated varactor. Its nominal frequency of oscillation is set by inductor L1, and a 390nH value places that frequency at 100MHz. Potentiometer R1 then allows you to choose a channel by tuning above the FM band of 88MHz to 108MHz. Output power is about -21dBm into 50 (most nations accept emissions below 10dBm in the FM band).

The home system's left and right audio signals are summed by R3 and R4, and attenuated by the (optional) potentiometer R2. R2's wiper signal serves as a volume adjustment by modulating the RF frequency. Signals above 60mV introduce distortion, so the pot attenuates down from that level.

In the absence of a common FM radio antenna, 75cm (30 inches) of wire will suffice as a transmitting antenna. For most effective reception, it need to be mounted parallel with the receiving antenna. The IC operates on a single power supply voltage inside the range 3V to 5V, but it is best to regulate the applied voltage to reduce frequency drift and noise.

80W Power Amplifier Circuit

2011-09-24T19:44:00.000-07:00

80W power amplifier circuit diagram based MJL4281A / MJL4302A and MJE15034 / MJE15035 power transistor. Actually the output power range is about 60W to 80W. This is an incredibly excellent amplifier. It's easy to construct, applies generally offered parts and is stable and well-performing. The diagram featured is really a full update on the original project, and even though it has a lot of similarities, is definitely a different design.

This amplifier circuit, even though extremely simple, is capable of great performance. This is not an amp to be under estimated, as the sonics are pretty good indeed, and this really is due (in part, at least) to the inherent simplicity of the diagram design. The amplifier is exceptionally quiet, and is reasonably tolerant of hard loads. It's an perfect amplifier for biamped systems, and may possibly be operated in bridge mode (BTL) in case you apply the suggested output transistors (which have the required power ratings).

Go to this 60-80W power amplifier page to get the detailed information about the circuit.

CMoy Headphone Amplifier Circuit

2011-09-15T04:21:00.000-07:00

The following diagram is the circuit of CMoy headphone amplifier. Chu Moy designed a very popular headphone amplifier that’s easy to build, and it can be built small enough to fit in a pocket, power supply and all. It’s powerful enough to drive very inefficient headphones to thunderous volumes from even weak sources

CMoy headphone amplifier circuit diagram:

The op-amp used for this circuit is OPA2132PA, you may use OPA2132P or OPA2134PA as the alternative op-amp chip.

Power supply circuit for CMoy headphone amplifier:

Go to this page for the complete tutorial of CMoy headphone amplifier circuit.

Multi-color LED Driver Schematic

2011-09-05T15:05:00.000-07:00

Have you ever wondered how many various colours can illuminate a LED? One, two or possibly three? Making this simple circuit, you will discover it a lot more. The important component in this design is a dual LED. One such accessory includes two inside the 'slices' of different diode LED, that each and every of them produces a different color (commonly green and red). For the drive needs three pins, a common cathode and two separate roots. In this way every single of the two integrated diodes can light up as independent of one another. You'll find only two colors that may create this dual LED.

Setting appropriate percentage of the currents flowing via two separate channels of the POY is, we have other from pure green and red, orange (IR = 21G) and yellow (IG = 2IR). In this circuit, the anodes of the double LED driven by the outputs a six-point buffer tri-state technology CMOS. As opposed to most integrated family of CMOS 4000, the 4503 applied here, can supply many different loads on high currents of the order of 10 mA. The stream that goes towards the two diodes is limited by the resistors R1 to R6 whose specific values are those that attain the distinct colors and changing brightness them. The circuit was originally created to display three various situations, each expressed their the presence of logical '1 'in one of the inputs a, b, c. The entries are able to activate only one of every single time, and if none of them had been excited, a NAND gate (IC1c) ensured that the LED 'to create fourth color. In the improved version we present these days, the circuit has added another level oscillator (IC 1 a and IC1b), which produces about two pulses per second. The pulses are introduced in the entrance activation OA (pin 1) of 4503, resulting in colorful flashes. The oscillator is controlled by the of logical statements applied to the inputs 'd' and 'e'. If both are simultaneously logical '1 ', then each the oscillator and also the buffers of 4503 stay inoperative. If e = 1 and d = 1, then all buffers are driven in a state of high resistance plus the circuit absorbs the least feasible electric current (standby). The power supply circuit was initially set at 12 Volt, but all of the components that are able to work equally properly with any voltage in between 5 Volt and 16 Volt.

6V Gel Cell Charger Circuit

2011-08-25T06:31:00.000-07:00

This is the diagram of 6V Gel Cell charger. The circuit is using NE555 timer as oscillator and TPI31T switching transistor. The schematic diagram designed by Tony Van Roon.

Parts List:

R1 = 22 ohm, 1W
R2 = 270 ohm
R3 = 220 ohm
*R4 = 715 ohm, 1%
*R5 = 3.57K, 1%
*R6 = 1.40K, 1%
*R7 = 1.47K, 1%

C1 = 100nF
C2 = 100nF
D1 = 1N4001
T1 = TIP31A, B, C (or equivalent)
U1 = Timer IC NE555V (or equivalent)
S1 = Toggle switch, ON-OFF

* Resistors type are carbon, 1/4 watt, 5% tolerance, unless otherwise indicated.

6V Gel Cell Charger circuit source page

6-8A / 0-28V Variable Power Supply Circuit

2011-08-18T02:33:00.000-07:00

This is the schematic diagram of variable power supply. The output voltage of this power supply circuit can be adjust from 0V to 28V DC, while the current output is static the rang is about 6A up to 8A.

Parts List:

R1 = 2K2 Ohm 2,5 Watt
R2 = 240 Ohm
R3,R4 = 0.1 Ohm 10 Watt
R7 = 6K8 Ohm
R8 = 10K Ohm
R9 = 47 Ohm 0.5 Watt
R10 = 8K2 Ohm
C1, C7, C9 = 47nF
C2 = 4700uF/50v – 6800uF/50v
C3, C5 = 10uF/50v
C4, C6 = 100nF
C8 = 330uF/50v
C10 = 1uF/16v
C11 = 22nF

D1…D4 = four MR750 diodes (MR750 = 6 Ampere diode) or 2 x 4 1N5401 diodes.
D5 = 1N4148, 1N4448, 1N4151
D6 = 1N4001
D10 = 1N5401
D11 = LED
D7, D8, D9 = 1N4001
TR = 2 x 15 volt (30volt total) 6+- Ampere
IC1 = LM317
T1, T2 = 2N3055
P1 = 5k
P2 = 47 Ohm or 220 Ohm 1 Watt
P3 = 10k trimmer pot
F1 = 1 Amp
F2 = 10 amp

Source: circuitdiagram.net

Electronic Siren Circuit

2011-08-13T15:01:00.000-07:00

This is the schematic diagram of electronic siren circuit. The sound produced imitates the rise and fall of an American police siren. When very first switched on, the 10uF capacitors is discharged and each transistors are off. When the push button switch is pressed to 10uF capacitor will charge via the 22k resistor. This voltage is applied towards the base of the BC108B which will turn on slowly. When the switch is released the capacitor will discharge via the 100k and 47k base resistors and also the transistor will slowly turn off. The change in voltage alters the frequency of the electronic siren.

Electric current drain is fairly high in this electronic siren circuit so a appropriate power supply is needed. The duration the tone takes to rise and fall is determined by the 10uF and 22k resistor. These values may possibly be varied for various effects.

Simple LM358 Mic Preamplifier

2011-08-02T00:21:00.000-07:00

This is a simple LM358 microphone preamplifier schematic diagram. The pre-amp circuit is very easy to build and.. it's a low cost project... The variable resistor R5 is to adjust the LM358 op-amp gain. The LM358 has dual op-amp circuit modules, you may use a single LM358 to build two channels mic preamplifier.

Parts List:
R1, R3, R4 = 10K
R2 = 1K
R5 = 100K-1M Potensiometer
C1 = 0.1uF
C2 = 4.7uF/16V
IC1 = LM358 dual op-amp single power supply
Mic = Electret Microphone

Stereo FM Transmitter 88-108 MHz based BA1404

2011-07-26T01:32:00.000-07:00

This is the stereo FM transmitter schematic diagram which built based BA1404. By using this HI-FI stereo FM transmitter, you will be able to transmit MP3 music from your iPod, computer, discman, walkman, TV / SAT receiver, and many other audio sources.

The transmitter can work from a single 1.5V cell battery and provide excellent crystal clear stereo sound. It can also be supplied from two 1.5V battery cells to provide the maximum range.

The kits of Stereo FM Transmitter 88-108 MHz based BA1404 available at electronics-diy.com, check it out

Offline Switching Power Supply Circuit (5V - 10A - 50W)

2011-07-22T15:40:00.000-07:00

Here the schematic diagram of offline switching power supply:

Circuit Diagram:

Parts List:

This switching power supply is using a MOSFET. For 220V AC voltage input, use BUZ80A/IXTP4N8 MOSFET and for 110V AC input voltage, use GE IRF823 MOSFET. The output will be 5 Volt DC with electric current can be reach 10A.

Echo Chamber Schematic

2011-07-20T15:02:00.000-07:00

The following diagram is the schematic diagram of echo chamber circuit which will convert the sound of input to have echo sound like repeating sound if you talking in a cave. It will smoothing your sound also.

The circuit based 4 main ICs that are a MN3005, a MN3101, and 4 pieces of AN6551. I've made this kind of circuit, it's working great and you don't have to spend a lot of cost. :)

Clock Generator Circuit

2011-07-14T01:02:00.000-07:00

This is the circuit diagram of Clock Generator circuit based NAND logic gate. You can use 4011 for CMOS IC and 7400 for TTL IC.

Circuit Notes:

Excellent clock generator to drive 4017 type CMOS circuits.
Fo is ±1Kz when R1=100K and C1=10nF.
R1 = 10K to 10M, C1 = 100pF to 47uF.
Input voltage can be from 5 to 15V.

Sample IC CMOS NAND gate 4011 pinout:

Basic Motorcycle Alarm circuit

2011-07-09T05:32:00.000-07:00

This is a very basic motorcycle alarm design circuit which can be used to secure your motorcycle with very low in cost.

Design schematic:

Circuit Number Five uses a SPCO/SPDT relay - but you actually only require to make use of a SPST relay. In case you are going to make use of the veroboard layout supplied - you will require to make use of the style of relay specified. But you are able to develop the alarm making use of whatever style of relay you've accessible.

Circuit Notes:
Any number of normally-open switches might be employed. Fit the mercury switches to ensure that they close when the steering is moved or when the bike is lifted off its side-stand or pushed forward off its centre-stand. Use micro-switches to secure removable panels and also the lids of panniers and so on. When 1 of the trigger-switches is closed - the relay will energize as well as the siren will sound.

You are able to select what will happen up coming. Should you develop the circuit as shown, the siren will continue to sound until you turn it off - or until the battery is exhausted. But, in the event you leave out D3 - the siren will stop sounding right away the trigger-switch is re-opened.

Whilst you are inside earshot of your machine - the former configuration is greatest. You are able to usually turn off the alarm your self. But in case you are going to be away from your bike for any length of time - and you do not wish to trigger a nuisance - then the latter configuration is possibly much more suitable. In the event you consist of a SPST switch in series with D3 - you'll be able to pick the behaviour that finest suits the circumstances at any given time.

Components placement:

Relay coils and some sounders generate high reverse-voltage spikes which will destroy sensitive electronic components. D1 and D2 are there to short-circuit these spikes just before they are able to do any harm. Even though there's absolutely nothing within the alarm circuit itself that might be damaged - I've no concept what other electronic equipment may be connected to the exact same power supply. So I included the two diodes as a precaution. If you are satisfied that there is absolutely nothing on your bike that may be damaged in this way - you'll be able to leave out the two diodes.

Basic Motorcycle Alarm circuit source: zen22142.zen.co.uk

Simple Servo Motor Controller circuit

2011-07-07T08:08:00.000-07:00

The following is the schematic diagram of simple servo motor controller circuit.

Simple Servo Motor Controller Parts List:

R1 = 820 Ohm 1/4W
R2 = 68K 1/4W
R3 = 10K 1/4W
R4 = 1K 1/4W
R5 = 1K Linear Taper Pot
C1 = 1uF/16V
Q1 = 2N3904 / 2N2222
U1 = 555 Timer IC
MISC = Board, Wire, Knob For R1, 8 Pin Socket For U1

The servo motor have many utilizes in everything from robotics to puppetry to photography and beyond. These tiny motors can position their output shaft to any position on command and hold that position. Most servos possess a range of motion to about 210 degrees and thankfully are quite easy to handle with a basic circuit like the one presented right here. Working with just a 555 timer as well as a couple of support parts, this circuit can handle a servo via it is full rotation primarily based on the position of a potentiometer.

Passive Surround Audio Circuit

2011-07-03T03:36:00.000-07:00

This is a passive surround audio circuit for better audio environment for your home audio system. The schematic diagram is very simple, it just need the combination of resistors and electrolytic capacitors.

Passive Surround Audio Circuit Notes:

The rear speakers must be full range type of speaker. Do not use woofer or tweeter speakers for rear speakers, you'll bad audio environment.
5W resistors is a must, the 1/4 or 1/2 watt resistor will burned.

Source: Passive audio surround

120V AC Line Powered LED

2011-06-28T21:28:00.000-07:00

The following circuit diagram shows you about how to powering a LED (or two) from the 120 volt AC line applying | working with a capacitor to drop the voltage together with a little resistor to limit the inrush electric current. Considering that the capacitor need to pass current in both directions, a modest diode is connected in parallel using the LED to supply a path for the negative half cycle and also to limit the reverse voltage across the LED. A second LED using the polarity reversed could be subsituted for the diode, or perhaps a tri-color LED might be put to use which would appear orange with alternating current. The circuit is fairly efficient and draws only about a half watt from the line. The resistor value (1K / half watt) was chosen to limit the worst case inrush electric current to about 150 mA which will drop to much less than 30 mA in a millisecond as the capacitor charges. This appears to be a secure value, I've switched the circuit on and off several times without having harm to the LED. The 0.47 uF capacitor has a reactance of 5600 ohms at 60 cycles so the LED current is about 20 mA half wave, or 10 mA average. A bigger capacitor will boost the electric current along with a smaller 1 will lessen it. The capacitor should be a non-polarized kind having a voltage rating of 200 volts or a lot more.

The lower circuit is an demonstration of obtaining a low regulated voltage from the AC line. The zener diode serves as a regulator and also supplies a path for the negative half cycle electric current when it conducts inside the forward direction. In this example the output voltage is about 5 volts and will give over 30 milliamps with about 300 millivolts of ripple. Use caution when operating any electronic circuits hooked up straight to the AC line.

120V AC Line Powered LED circuit source:
http://www.bowdenshobbycircuits.info/page10.htm#lineled.gif

14W Audio Amplifier Circuit

2011-06-26T09:05:00.000-07:00

This Amplifier circuit designed by Mike Ellis at 1999. The amplifier capable to deliver up to 14W power audio output. The pre-amp circuit already designed in the circuit and direct connected to the amplifier modul.

Here the 14W Audio Amplifier schematic diagram:

For detailed explanation about this 14W amplifier circuit, visit the following page:
http://michaelgellis.tripod.com/audioamp.html

Video Amplifier Circuit based LH0032

2011-06-22T15:53:00.000-07:00

The following is the schematic diagram of Video Amplifier circuit, built based on LH0032, a high speed op-amp applications.

Video Amplifier Parts List:
R1 = 15Kohm+15Kohm
R2,R3,R4 = 10Kohm
R5,R6,R7,R8,R9 = 1Kohm
R10 = 820ohm
R11 = 1Mohm
R12 = 100ohm trimmer
R13,R15 = 47ohm
R14 = 10Kohm
C1 = 10uF 63V MKT
C2,C4 = 100nF 63V
C3 = 4.7pF ceramic
IC1 = LH0032
S1 = 1X2 mini switch
S2 = 1X6 sel.
J1,J2 = BNC connector

The LH0032 are very high speed general purpose operational amplifiers exhibiting 70 MHz bandwidths, 500 V/μs slew rates and 100 to 300 ns settling time to 0.1%. The LH0032 has the added advantage of FET input characteristics.

Fading LEDs Circuit

2011-06-19T19:45:00.000-07:00

The following diagram is the schematic diagram of fading LEDs circuit. This kind of circuit runs two LED strips in pulsing mode, i.e. one LED strip goes from off state, lights up gradually, then dims little by little, and so on. while one other LED strip does the contrary.

Components part:

R1, R2 = 4K7
R3 = 22K
R4 = 1M *
R5 = 2M2 *
R6, R10, R11, R14, R15 = 10K
R7, R8 = 47K Trimpot *
R9, R13 = 27K
R12, R16 = 56R

C1 = 1µF
C2 = 100µF/25V
D1-D4 etc = 5 or 3mm LEDs *
IC1 = LM358
Q1, Q2 ,Q4 = BC327
Q3, Q5, Q6 = BC337
SW1 = SPST miniature Slider Switch
B1 = 9V PP3 Battery

Circuit Works:

The IC1 contains two Op-Amps circuit which will be used to generate triangular wave form.. The rising and falling voltage obtained at pin #7 of IC1 drives two complementary circuits formed by a 10mA continual current source (Q1, Q2 and Q5, Q6) and driver transistor (Q3 and Q6).
R4, R5 & C1 are the timing components: the total period can be varied changing their values. R7 & R8 vary the LEDs brightness.

Fading LEDs Circuit Notes:

For those whishing to avoid the use of trimmers, suggested values for 9V supply are: R4=3M9, R9 & R13=47K and trimmers replaced by a short.
Whishing to use a wall-plug adapter instead of a 9V battery, you can supply the circuit at 12V, allowing the use of up to 6 LEDs per strip, or at 15V, allowing the use of up to 7 LEDs per strip.
In this case, the value of the trimmers R7 & R8 should be changed to 100K.

Fading LEDs Circuit Source: RedCircuits

50W Amplifier Circuit based ICL8063 + 2N3055

2011-06-14T02:27:00.000-07:00

50W Amplifier Circuit, built based ICL8063 as power transsistor driver and 2N3055 as main power amplifier component.

50W Amplifier Circuit based ICL8063 + 2N3055 schematic diagram:

Parts List:

R1 = 200 Ohm
R2 = 200K
R3 = 30K
R5 = 1K
R6 = 5K
R7, R10 = 1 Meg
R8,R9 = 0.4 Ohm/5Watt
R11 = 10K Potensiometer
R12,R13 = 51K
R14 = 47K
C1 = 100uF/35V
C2 = 0.011uF
C3 = 3750pF
C4,C6 = 1000pF

C5,C7,C8 = 0.001uF
C9 = 50pF
C10 = 0.3uF
C11,C12 = 10.000uF/50V
U1,U2 = 741 Op Amp
U3 = ICL8063 Audio Amp Transister Driver
Q1 = 2N3055 NPN Power Transistor
Q2 = 2N3791 PNP Power Transistor
BR1 = 250 V 6 Amp Bridge Rectifier
T1 = 50V Center Tapped 5 Amp Transformer
S1 = SPST 3 Amp Switch
S2 = DPDT Switch
F1 = 2 Amp Fuse
SPKR1 = 8 Ohm 50W Speaker

Circuit Notes:

Distortion is much less than 0.1% up to 100HZ and increases to about 1% at 20kHz.
50V CT transformer might be difficult to find, you may use 45V or 32V CT transformer.
Q1 and Q2 should be use heatsinks to prevent over heating.

50W Amplifier Circuit based ICL8063 + 2N3055 source page

LM3886: 68W Power Amplifier

2011-06-10T10:15:00.000-07:00

This is a good amplifier circuit taken from electronic-diy.com. Built based LM3886, the amplifier capable to deliver up to 68W audio output.

Parts List:

R1 = 10K Ohms
R2 = 10 Ohms 2W see text
R3 = 10 Ohms
R4 = 47K Ohms
R5 = 220K Ohms
R6 = 10K Ohms
R7 = 100K Ohms
L1 0,7uH
IC1 LM3886

C1 = 100NF
C2 = 100NF
C3 = 100NF
C4 = 100UF
C5 = 100UF
C6 = 4,7UF
C7 = 100UF
C8 = 1UF

The amplifier should be supplied by +34 and –34 volts. R2 and L1 is a resistor of 10 ohms / 2 watt coiled with 10 to 12 you exhale of enameled thread AWG 20.

68W Power Amplifier circuit diagram based LM3886

25W Power Amplifier with MOSFET IRF530/IRF9530

2011-06-06T04:17:00.000-07:00

This is a MOSFET powered amplifier circuit. The circuit output will be 25 Watt RMS @ 8 Ohm (1KHz sine wave) with frequency response of 30Hz to 20KHz -1dB.

Components Part:

R1, R4 = 47K
R2 = 4K7
R3 = 1K5
R5 = 390R
R6 = 470R
R7 = 33K
R8 = 150K
R9 = 15K
R10 = 27R
R11 = 500R
R12, R13, R16 = 10R
R14, R15 = 220R
R17 = 8R2 - 2W Resistor
R18 = R22 - 4W Resistor (wirewound)

C1 = 470nF/63V
C2 = 330pF/63V
C3, C5 = 470µF/63V
C4, C6, C8, C11 = 100nF/63V
C7 = 100µF/25V
C9 = 10pF/63V
C10 = 1µF/63V
Q1-Q5 = BC560C
Q6 = BD140
Q7 = BD139
Q8 = IRF530
Q9 = IRF9530

Circuit Notes:

This circuit dual polarity power supply to supply the amplifier.
This audio amplifier can be directly connected to CD players, tuners and tape recorders. Just add a 10K Log potentiometer (dual gang for stereo) along with a switch to cope using the different sources you need.
Q6 and Q7 must have a small U-shaped heatsink.
Q8 and Q9 must be mounted on heatsink.
Adjust R11 to set quiescent current at 100mA (best measured with an multimeter connected in series to Q8 Drain) with no input signal.
A correct grounding is very important to eliminate hum and ground loops. Connect to the same point the ground sides of R1, R4, R9, C3 to C8. Connect C11 to output ground. Then connect separately the input and output grounds to power supply ground.

Electronic Chirping Canary Circuit

2011-06-01T17:17:00.000-07:00

Well, for those of you who want to make a small project, this alarm may be an option for you. This circuit will generate the canary chirping sound. The chirp sound of a canary is generated by the oscillation process by resistor R1 and capacitor C1. The capacitor, having a capacitance value of 100 uF, is charging through the resistor, having a resistance of 4.7 K ohms. During this stage, R1 is the bias for the transistor making it operate in the cut off. When the transistor is in cut off mode, the base-emitter voltage is very minimal for any considerable current to flow. This mode triggers the oscillation to end but will start again once the capacitor discharges across the transmitter’s base-emitter circuit.

The frequency of the chirp may be modified by changing the values of the resistor and capacitor. The charging of the capacitor occurs when operating the push button switch. By releasing the button, the chirping runs quicker whilst the oscillation weakens.

The loudspeaker is being driven and coupled to the circuit by the miniature audio transformer of LT700 which having a frequency of 1 kHz. This circuit can be supplied with 9V battery.

Electronic chirping canary circuit source: http://www.elecpod.com/circuit/av/2010/03011410.html

100W Transistored Inverter 12VDC to 220VAC

2011-05-28T19:28:00.000-07:00

This inverter circuit can be used for medium electronic devices such as emergency light, radio, battery charger etc. Be carefull during assembly this circuit because of high voltage on the output transformer.

100W Inverter PCB Diagram:

100W Inverter PCB Design Layout:

Source of the circuit: 100W Interver Circuit

9V Mini FM Transmitter

2011-05-13T15:15:00.000-07:00

The following diagram is the circuit diagram of 9V Mini FM Transmitter.

Schematic diagram:

Components List:

R1,R3 = 100K
R2 = 10K
R4 = 470 ohm
C1,C4 = 470pF
C2,C3 = 4.7µF/16V
C5,C6 = 4.7pF
C7 = 4-40pF trimmer cap (optional, see text)
L1 = 1µH
Q1,Q2 = 2N2222, NPN transistor
Mic = Electret Microphone
B1 = 9 Volt battery

Circuit Notes:
Absolutely nothing crucial here. To get a bit of tuning out of the coil you could put a 4-40pF trimmer capacitor (optional) parallel over the 1 µH coil, L1.

C1/C4 and C5/C6 are ceramic capacitors, preferably NPO (low noise) types. C2/C3 are electrolytic or can be tantalum kinds.

In the event you determine to substitute transistors with some thing similar you already have, it perhaps necessary adjust the collector voltage of Q1 by changing the value of R2 or R3 (simply because you alter transistors, it changes this bias on the base of Q1). It ought to be about 1/2 the supply voltage (about four or 5v).

The antenna is nothing more than a piece of 12" wire or a piece of piano wire from 6" to 12".

To find the signal on your regular FM Radio dial, make certain there's a signal coming into the microphone, otherwise the circuit will not function. I use an old mechanical alarm clock (you know, with those two big bells on it). I put this clock by the microphone which picks up the loud tick-tock. I'm certain you get the concept... Or you can just lightly tap the microphone whilst looking for the location of the signal on your receiver.

The antenna is nothing more than a piece of 12" wire or a piece of piano wire from 6" to 12".

To find the signal on your standard FM Radio dial, make sure there is a signal coming into the microphone, otherwise the circuit won't work. I use an old mechanical alarm clock (you know, with those two large bells on it). I put this clock by the microphone which picks up the loud tick-tock. I'm sure you get the idea... Or you can just lightly tap the microphone while searching for the location of the signal on your receiver.

Source: http://www.sentex.ca/~mec1995/circ/fmt4.html
Design by Tony van Roon

Touch Activated Alarm

2011-05-06T15:49:00.000-07:00

This is a touch activated alarm system. Your alarm system will be activated when someone touching the "trigger". You may use this circuit at your home door, your vehicle etc.

Parts list:

R1 = 100K
R2 = 56K
R3 = 10M
R4 = 220K
P1 = 100K
D1 = 1N4004

T1 = 2N3904, or equivalent
U1 = 555 Timer*
C1 = 47μF/16V**
C2 = 33μF/16V**
Re1 = Relay***

Notes:

*The 555 can be a LM, NE, or MC(cmos) type, they're all pin-compatible.

**C1/C2's working voltage ought to be elevated to 25V in the event you decide to go with a 12V power source. Rule of thumb: the operating voltage of capacitors are at least double the supplied voltage, in other words, if the power source is 9 Volt, your capacitor(s) is a minimum of 18V. Transistor T1 could be any approximate substitute.

*** Use any appropriate relay for the project and if you're not tight on area, use any size. I've build this specific circuit to prevent students from fiddling using the security cameras in pc labs at the University I'm employed. I made sure the metal casing was not grounded. But as being the schematic shows you are able to essentially hook it as much as any type of metal surface. I utilized a 12-vdc power supply. Use any suitable relay to deal with your specifications. A 'RESET' switch (Normally Closed) can be added between the constructive and also the 'arrow-with-the-+'. The trigger (touch) wire is connected to pin 2 of the 555 and will trigger the relay, using the body resistance, when touched. It is apparent that the 'touching' component has to be clean and can make good contact using the trigger wire. This particular circuit might not be suitable for all applications. Just in case you wonder why pin 5 is not listed within the schematic diagram; it is not really required. In particular noisy circumstances a little ceramic capacitor is placed between pin 5 and ground. It will no harm to put one or leave it out.

Additional note: For those of you who didn't discover, there's an approximate 5-second delay build-in before activation of the relay to avoid false triggering, or perhaps a 'would-be' thief, and so on.

Circuit design by Tony van Roon.

Emergency Light and Alarm circuit

2011-04-26T01:13:00.000-07:00

This is a simple and easy emergency light and alarm circuit. This circuit is permanently plugged into a mains socket and NI-CD batteries are trickle-charged. When a power outage occurs, the lamp automatically illuminates. Instead of illuminating a lamp, an alarm sounder can be chosen.

When power supply is restored, the lamp or the alarm is switched-off. A switch provides a "latch-up" function, in order to extend lamp or alarm operation even when power is restored.

Component parts list:

R1 = 220K
R2 = 470R
R3 = 390R
R4 = 1K5
R5 = 1R
R6 = 10K
R7 = 330K
R8 = 470R
R9 = 100R
C1 = 330nF/400V Polyester Capacitor
C2 = 10µF/63V Electrolytic Capacitor
C3 = 100nF/63V Polyester Capacitor
C4 = 10nF/63V Polyester Capacitor
D1-D5 = 1N4007
D6 = LED Green
D7 = 1N4148
Q1,Q3,Q4 = BC547
Q2,Q5 = BC327
SW1,SW2 = SPST Switches
SW3 = SPDT Switch
LP1 = 2.2V or 2.5V 250-300mA Torch Lamp Bulb
SPKR = 8 Ohm Loudspeaker
B1 = 2.5V Battery (two AA NI-CD rechargeable cells wired in series)
PL1 = Male Mains plug

Circuit Works:
Mains voltage is reduced to about 12V DC at C2's terminals, by means of the reactance of C1 and the diode bridge (D1-D4). This avoids the use of a mains transformer.

Trickle-charging current for the battery B1 is provided by the series resistor R3, D5 and the green LED D6 that also monitors the presence of mains supply and correct battery charging.
Q2 & Q3 form a self-latching pair that start operating when a power outage occurs. In this case, Q1 biasing becomes positive, so this transistor turns on the self latching pair.

If SW3 is set as shown in the circuit diagram, the lamp illuminates via SW2, which is normally closed; if set the other way, a square wave audio frequency generator formed by Q4, Q5 and related components is activated, driving the loudspeaker.

If SW1 is left open, when mains supply is restored the lamp or the alarm continue to operate. They can be disabled by opening the main on-off switch SW2.

If SW1 is closed, restoration of the mains power supply terminates lamp or alarm operation, by applying a positive bias to the Base of Q2.

Notes:

Close SW2 after the circuit is plugged.
Warning! The circuit is connected to 230Vac mains, then some parts in the circuit board are subjected to lethal potential!. Avoid touching the circuit when plugged and enclose it in a plastic box.

Emergency Light and Alarm circuit source: http://www.redcircuits.com/Page45.htm

Amplifier Circuit based 4 Transistors

2011-04-23T08:40:00.001-07:00

Above diagram very simple and easy to build class AB audio amplifier circuit which is working with 4 transistors. In class AB operation each output device performs more than half of the input signal cycle. Up to 78% effectiveness is possible with class AB designs and cross over distortion is minimized. The circuit shown here is appropriate for small radio receivers, audio players, intercom, phone etc.

Transistor Q1 with its connected parts is wired as a pre-amplifier stage. The audio input is coupled to the base of Q1 through resistor R1 and capacitor C1. Resistor R3 delivers collector to base bias for Q1 and C3 is an AC by pass capacitor for the collector resistor R4. Collector to base biasing is a great method of biasing for circuits like this because it provides enough negative feedback, prevents thermal runway and stabilizes the operating point. The second stage will be the driver stage for the push pull pair. Q2 with its connected parts carry out this job. This stage can also be collector to base biased, and its input is coupled towards the output from the pre-amplifier stage using capacitor C2. Resistor R8 limits the collector present of Q2.The third stage is the class AB push pull section comprising of transistors Q3 and Q4. Diodes D1 and D2 provides the bias voltage for the push pull stage. The output from the amplifier is coupled to the loud speaker through the capacitor C4. C5 and C6 are power supply filter capacitors.

Notes:

The circuit can be assembled on a vero board.
K1 may be an 8 ohm/5Wof loud speaker.
C6 must be grounded near towards the Q1 and C5 should be grounded near to the loud speaker ground. This reduces noise.
Use 5V DC power supply for powering the circuit.

EL34 Stereo Tube Amplifier 2x90 Watts

2011-04-18T22:31:00.000-07:00

The following are step by step how to create a stereo tube amplifier using EL34 power tube. This stereo tube amplifier circuit is capable of producing an audio output of 90 watts for each channel.

Download EL34 Stereo Tube Amplifier 2x90 Watts step by step guide.
Download Link

220V Light Dimmer circuit

2011-04-08T20:18:00.000-07:00

The following diagram is the schematic diagram of 220V Light Dimmer.

220V Light Dimmer diagram:

Parts List:
R1 = 10K
R2 = 2K2
R3 = 180K
Potentiometer 250K
C1 = 150nF/400V dipped polyester
C2 = 47nF/630V dipped polyester
C3 = 220nF/250V AC dipped polyester
Triac = 2N6075 or BT136-500D
Diac = HT-32
FUSE 2A or 3A

Download the 220V Light Dimmer circuit documentation here.

35W Power Amplifier Circuit using STK082

2011-03-23T14:30:00.000-07:00

The following is the schematic diagram of 35W power audio amplifier. Built based on power-amp IC of STK082, this circuit will give great audio output for your home audio system.

Download the STK082 datasheet

Easy LED Flasher Schematic

2011-03-10T14:34:00.000-08:00

Here the schematic diagram of Easy LED Flasher circuit:

Parts List:

R1 = 10M ohm
R2 = 1K – 100K ohm
R3 = 470 ohm
C1 = 0.47μF – 10μF/25V

D1 = 1N914
Q1 = 2N3904
Q2 = 2N3906
Led = High Brightness Red LED

This circuit will flash a bright or high-brightness red LED (5000+ mcd). Very good for fake car alarm or other attention getting device. Part values are not significant, test something else to start with from your junkbox.Certainly, the 470 ohm resistor (R3) determines the LED's brightness and limits the current supply to around 20mA. R3 value of 390 ohm may also be applied as a save value.

If you decide to go using a green or yellow led, which take more current, you might want to change the 470 ohm with an suitable value. Flash speed is established by R2 and C1 and is roughly three time constants (3*R2*C1). R1 provides bias to Q1 which ought to be small enough not to saturate Q2 with the capacitor disconnected. When the circuit doesn't oscillate, R1 may be very low or R2 too high. D1 allows for highter duty cycle operation and limits the feedback at the base of Q1 to -0.7 volts. D1 might be ommited for low supply power like 6 - 9V and low duy cycle operation.

Easy Build RF Transmitter

2011-02-15T00:35:00.000-08:00

This circuit most likely the easiest and simplest radio transmitter which you will get anyplace. It uses total of 5 components and could be built into a really compact space. It's very good for science fair projects or other science related projects in which a small range transmission is useful.

It works on 1.5 to 3 V, with small hearing aid battery packs or lithium "coin" cells becoming excellent. A thermistor or photoresistor may be inserted in series with R1 to get a various output frequency depending on the input.

The frequency may also be adjusted by modifying the value of C1. A 2N2222 transistor is highly recommended, but you are able to try out other types as well. Performance is likely to vary from type to type as well as from transistor to transistor. L1 is 20 to 30 turns of thin magnet wire (24 to 32 ga.) close wound about a 1/8 to 1/4" diameter non-conductive form. The coil is normally tapped 1/3 of the way from one end and also the tap connected to the emitter of Q1. Try out with all of the values in this particular circuit. Nothing is vital, but the result may be varied considerably.

Pipe Bomb Mic Construction

2011-02-12T00:29:00.000-08:00

Pipe Bomb Mic Construction, by Jamie Heilman:
My own dimensions for my prototype are X= 36cm, Y= 5.5cm. This imparted a fairly high pitch tone but I like it.

The X and Y dimensions really should be played with to develop the precise tone your seeking, also I chose a telephone loudspeaker as well as a crystal mic so I got the funkiest tone I could think of. A dynamic microphone might limit the treble somewhat most likely make it sound less harsh. I’d be considering any mods produced to this style (ie. stories, suggestions, etc.) so feel free to e mail me.

The amps may be any old easy op-amp construction that can drive a loudspeaker or take a mic input. I just made use of some excess material I had lying around to make mine. The end product had all the circuitry inside the tube and the battery pack on the outside, with one control for the gain of the loudspeaker (mic was at fixed gain).

Note, in case you locate this in the front of the amplifier and turn every thing up, without having adding any dampening to the pipe, it will feedback just like you wont imagine! You'll most likely wish to keep away from this because it tends to hurt your ears. I put a bit of foam rubber in one end of the tube and an old sock in the other to dampen feedback. I like to leave my alternatives open though, so I also didn’t make this a permanent addition. My prototype is essentially a fuzz, as my guitar will overload the loudspeaker fairly simply and the pipe just adds a bit of strange overtone and what I believe is the smallest hint of reverb. Sounds excellent though! Clean tones via a similar set up would sound good too, but I haven’t constructed one of those yet. Possibly a larger speaker (4-5") and an old carpet pipe would probably add improved characteristics for clean tones. Attempt changing the tube material also for a various tone, I almost applied a bit of gutter piping when I 1st built this, right now I wonder what it would’ve sounded like.

Download the document about how to build Pipe Bomb Mic in PDF file:
Download Link

Transistored Stereo Tone Control

2011-02-09T00:34:00.000-08:00

Here the circuit diagram of stereo tone control system which also available on the market in circuit kit, you might get the kit at electronic component/part store near your area. The tone control require 12v of supply voltage to work.

The circuit designed based on common tone control circuit, by using two transistors FCS9014 in each channel, so there are actually four transistors in this 12v stereo tone control. Take a note that you need to install the circuit prior to the amplifier device. The output of tone control should be connected towards the input of the audio amplifier. Any small signal NPN transistor such as BC547B, 2N3904, C828, or C945 may be put to use to replace FCS9014.

Very Easy R/C Circuit

2011-02-03T14:55:00.000-08:00

The following diagram is a very easy and efficient receiver for actuating garage doors, starter motors, alarms, warning systems and numerous some other possibilities.

The SCR, that has a extremely low trigger present of 30 uA is common -- it requires an input electric power of just 30 uW to switch on the relay. A high Q tuned antenna circuit assures rejection of spurious signals. A whip or wire antenna is adequate as much as 100 feet from a low power transistor transmitter. A momentary-off switch resets the circuit.

The circuit specifies a whip or wire antenna which just indicates a solid piece of wire 6-12 inches long (15-30cm). The antenna coil is experimental, however you can start with ten to 12 turns of #22 (0.7mm) magnet wire, and 5/16" (8mm) coil diameter. Antenna wire is soldered at 1/2 turn of the coil and the gate of the BRY35 is soldered about halfway the coil. This circuit will transmit as much as 100-feet with the above specs @ 30uA.

The relay coil is specify's as much as 200 ohm but that's just the one I had in stock. Any low-ohm relay, even at 9V or so, ought to accomplish the task. And one remaining note, do not be expecting too a lot from this circuit. The "Very Easy R/C Circuit" is simply that; Easy!

The BRY35 is really an classic semiconductor produced by Philips. A great replacement would be the EC103D1, also produced by Philips (see pin-out picture for this device). NTE Semiconductors gives an alternative of NTE5405, but I have not attempted it. I think, a NTE5400 (30V) or NTE5401 (60V) will function just also. The NTE5405 is a bit overkill at 400V.

60W Inverter Circuit

2011-01-26T19:40:00.000-08:00

Above circuit is a inexpensive completely transistorised inverter circuit ideal for driving medium loads of the order of 40 to 60 watts working with battery of 12V, 15 Ah or bigger power capacity.

Transistors T1 and T2 (BC548) make a 50Hz multivibrator. For having proper frequency, the values of resistors R3 and R4 may have to be modified after testing. The complementary outputs from Collectors of transistors T1 and T2 are provided to PNP darlington driver stages formed by transistor pairs T3-T4 and T6-T7 (utilising transistors BD140 and 2N6107). The outputs from the drivers are given to transistors T5 and T8 (2N3055) connected for push-pull operation.

Considerably bigger wattage could be achieved by growing the drive to 2N3055 transistors (by lowering the value of resistors R7 and R8 while increasing their wattage). Appropriate heatsinks may be applied for that output stage transistors to prevent the transistor from overheating. Transformer X1 is really a 230V primary to 9V-0-9V, 10A secondary used in reverse.

Download the document about this 12VDC to 230VAC 60W Inverter Circuit Here

Guitar Effect Circuit : Electro Harmonix Big Muff Pi

2011-01-06T22:42:00.000-08:00

This Electro Harmonix Big Muff Pi circuit would most likely be better making the change by a contemporary input-jack power and a DPDT bypass switch. The kinds of transistors and diodes are unknown. It really is most likely that any high acquire NPN transistor and diode 1N914 will work. Coupling capacitors marked with * have been reported at its greatest if it has altered to 0.1uF and also the capacitors marked with ** modified to one.0UF. The unique transistors had been labeled SPT 87-103, and diodes of origin are marked or 525GY or 523GY (hard to examine.)

Download Electro Harmonix Big Muff Pi schematics in PDF:
Download Link

KA2211, 5.8W Stereo Audio Amplifier

2010-12-18T19:53:00.000-08:00

The following schematic is the diagram of 5.8 stereo power amplifier based on Samsung IC KA2211. The 5.8W is the power output on each channel, it means that the output will be 2 x 5.8W (maximum).

About KA2211:
KA2211 is a dual audio power amplifier for consumer application. It is designed for high power, low dissipation dan low noise. Is also contains various of protectors and suitable for high performance car audio power amplifier.

Download the datasheet document of KA2211 HERE

TDA1521 / TDA1521Q: 12W Stereo Amplifier

2010-12-12T02:40:00.000-08:00

This is a stereo audio amplifier circuit that provides 12W output power on each audio channel. This simple circuit is built on a single integrated circuit of TDA1521 / TDA1521Q, and only supported by few external components.

TDA1521/TDA1521Q is a dual high-fidelity audio amplifier encapsulated in a plastic 9-leads. The device is specially designed for power supply applications (eg, stereo TV and radio). A heatsink is needed to prevent overheating the IC.

TDA1521/TDA1521Q features:

Requires very few external components
Low offset voltage between output and ground
Input muted during power-on and off
(no switch-on or switch-off clicks)
Hi-fi according to IEC 268 and DIN 45500
Excellent gain balance between channels
Short-circuit-proof
Thermally protected

This hi-fi stereo power amplifier is designed for mains fed applications. The circuit is designed for both symmetrical and asymmetrical power supply systems. An output power of 2 x 12 watts (THD = 0,5%) can be delivered into an 8 W load with a symmetrical power supply of ± 16 V.

Download the TDA1521/TDA1521Q Datasheet Here

Basic Monostable Multivibrator based IC 555

2010-12-02T02:28:00.000-08:00

The following diagram is the circuit diagram of the very basic monostable multivibrator which built based on timer IC 555.

Parts list:
R1 = see notes
C1 = see notes
C2 = 10nF
IC1 = LM555

Notes:

R1 and C1 determine length of output pulse where t=R1xC1 and R1 is in ohms and C1 is in farads.
Pin 4 is the RESET. Leave it connected to power supply (+V) during normal operation. Bring pin 4 AND pin 2 low at the same time to reset timing cycle.

Portable Amplifier based on TEA2025

2010-11-16T22:29:00.000-08:00

This is the diagram of simple portable amplifier circuit. This amplifier circuit build based on IC TEA2025 that is a monolithic integrated audio amplifier of 16-pin plastic dual in line package built by UTC manufacture. The circuit has an internal thermal protection. The circuit designed for portable cassette players and radios. You can also use as PC audio amplifier.

Here the amplifier diagram for stereo audio input/output:

and here the amplifier with mono audio input/output (bridge):

Stereo per channel
VCC=9V; RL=4 ohm/3W
VCC=9V; RL=8 ohm/2W

Bridge Application
VCC=9V; RL=8 ohm/5W
VCC=9V; RL=4 ohm/8W

Supply Voltage min = DC3v @ 500mA
Supply Voltage max = DC12v @ 500mA
Supply Voltage recommended = DC9v @500mA

Download TEA2025 Datasheet
Download the schematic diagram in PDF format HERE

2x22W Stereo Power Amplifier circuit based TDA1554

2010-10-22T23:43:00.000-07:00

This is is a stereo power amplifier circuit works up to 22W on each channel. It will be 2x22W output. A few externel components required to support the main component of TDA1554. Heatsink on the power IC is a must to prevent overheating on the power IC. The chip should run cool enough to touch with the proper heatsink installed.

Component part list:

R1__________39K 1/4 Watt Resistor
C1,C2_______10uf 25V Electrolytic Capacitor
C3__________100uf 25V Electrolytic Capacitor
C4__________47uf 25V Electrolytic Capacitor
C5__________0.1uf 25V Ceramic Capacitor
C6__________2200uf 25V Electrolytic Capacitor
U1__________TDA1554 Two Channel Audio Amp Chip
MISC________Heatsink For U1, Binding Posts (For Output), RCA Jacks (For Input)

Operated at 12 Volts and at about 5 Amps at full volume. Lower volumes use less current, and therefore produce less heat. Printed circuit board is preferred, but universal solder or perf board will do. Keep lead length short.

LM3886 , 100W Power Audio Amplifier circuit

2010-10-13T17:47:00.000-07:00

The following circuit diagram is the 100 Watt power audio amplifier circuit, build based on power amp chip LM3886. The single chip of IC LM3886 is able to amplify the audio power output up to 68W.

In this circuit, the two of LM3886 are paralled to gain more powerful amplifier output. This amplifier can deliver about 50W into a 8-ohm speaker and 100W into a 4-ohm speaker. To make a stereo amplifier, there are should be use 4 pieces of LM3886.

Circuit source: http://www.shine7.com/audio/pa100.htm

20W Bridge Car Amplifier based TDA7240A

2010-09-04T23:53:00.000-07:00

The following circuit diagram is a bridge amplifier which specially designed for car audio system. The circuit is very simple with few external components supporting the power IC TDA7240A. This circuit will produce a maximum power output of 20W

Schematic Diagram:

PCB Layout:

The circuit diagram and PCB layout come from the IC TDA7240A datasheet. Download TDA7240A datasheet for circuit reference.

Positive Variable Power Supply circuit

2010-08-22T21:45:00.000-07:00

The following diagram is the schematic diagram of positive adjustable/variable power supply. It means that the power supply output will be DC current with positive [+] and ground [0] polarity.

Schematic diagram:

Power Supply Input:

Component part list:
R1 = 330
R2 = 1K
VR1 = 10K 10-turn trimpot
C1 = 2200uF/50V
C2,4 = 100nF ceramic
C3,4 = 10uF/63V
D1-6 = 1N5403
REG IC = LM317T
Heatsink

Visit this page to download the variable power supply diagram manual.

32W HiFi Amplifier circuit based on TDA2050

2010-08-08T16:40:00.001-07:00

This is a High Fidelify (Hi-Fi) amplifier circuit based on single IC TDA205. This is a mono channel audio amplifier. You need to build the same circuit for stereo channel.

Schematic diagram:

PCB Design:

TDA2050 Description:
The TDA 2050 is a monolithic integrated circuit in Pentawatt package, intended for use as an audio class AB audio amplifier. Thanks to its high power capability the TDA2050 is able to provide up to 35W true rms power into 4 ohm load @ THD =10%, VS = ±18V, f = 1KHz and up to 32W into 8ohm load @ THD = 10%, VS = ±22V, f = 1KHz. Moreover, the TDA 2050 delivers typically 50W music power into 4 ohm load over 1 sec at VS=22.5V, f = 1KHz.

The high power and very low harmonic and crossover distortion (THD = 0.05% typ, @ VS = ±22V, PO = 0.1 to 15W, RL=8ohm, f = 100Hz to 15KHz) make the device most suitable for both HiFi and high class TV sets.

Download TDA2050 datasheet for the circuit reference.

TDA7295, 80W Audio Amplifier

2010-07-20T03:18:00.000-07:00

Below is a schematic diagram of the 80W power amplifier based on single Power IC TDA7295. With simple diagram, this circuit will be easy to build.

The IC TDA7295 is a monolithic integrated circuit , intended for use as audio class AB amplifier in Hi-Fi field applications such as home theatre and topclass TV.

Continue reading about this 80W audio amplifier.

Triangle Wave and Square Wave Generator

2010-06-15T15:04:00.000-07:00

This is a simple circuit diagram of triangle wave and square wave generator.

The circuit is designed based on a common 1458 dual op-amp that can be used from very low frequencies to about 10 Khz. The time interval for one half cycle is about R*C and the outputs will supply about 10 milliamps of current. Triangle amplitude can be altered by adjusting the 47K resistor, and waveform offset can be removed by adding a capacitor in series with the output.

source of Triangle Wave and Square Wave Generator circuit:
http://www.high-voltage-lab.com/211/triangle-squarewave-generator

10W Audio Amplifier circuit based on TDA1910

2010-05-24T18:50:00.001-07:00

Simple and cheap, that's the advantage of this circuit. Although the output power is not high but audio quality is good, because TDA1910 has a very low noise feature. This circuit suitable for use as a student project.

About TDA1910:
The TDA1910 is a monolithic integrated circuit in MULTIWATT® package, intended for use in Hi-Fi audio power applications, as high quality TV sets.

The TDA 1910 meets the DIN 45500 (d = 0.5%) guaranteed output power of 10W when used at 24V/4W. At 24V/8W the output power is 7W min.

TDA1910 Features:

muting facility
protection against chip over temperature
very low noise
high supply voltage rejection
low “switch-on” noise.

Download TDA1910 Datasheet for complete TDA1910 reference

Simple FM Transmitter

2010-05-13T00:37:00.000-07:00

This FM transmitter claimed to be a very good transmitter. This circuit is worked very well since this circuit is actually copied from available electronic kit.

Component part:

R1 100K
R2 220K
R3 22R
R4 1K trimmer
R5 1K
R6 56K
R7 1M
R8 1K2
T1 BF244A or BF245A FET
T2 2N3819 FET
T3 BC307/8/9 or BC557/8/9 PNP

D1 Varicap diode (eg. BB119)
D2 1N4148
C1 5pF ceramic
C2 6pF ceramic
C3 15pF ceramic
C4 trimmer cap
C5 15pF ceramic
C6 1nF ceramic
C7 100uF electrolytic
C8 4.7uF electrolytic
C9 100pF ceramic

Frequency range is 100-108 MHz. The circuit is only mono circuit, and accepts an audio input from either a microphone or other source. The input impedance is 1Mohm. The input sensitivity is 5mV and the max input signal is 10mV. The transmitted signal can be picked up on a FM radio. The circuit can be used for short-range transmission, eg. for wireless microphones.

The power supply to use is 9-14 V DC, one of the little rectangular 9V batteries is fine. Connect this to the + and - points on the PCB. The sound input goes to the points marked "MIKE". The antenna should be connected to the point marked "ANT". The emitter's output impedance is 50 ohms. You can make your own fancy antenna if you like.

Source: http://www.high-voltage-lab.com/77/small-radio-transmitter

50W Power Amplifier circuit based on STK-1050

2010-04-28T07:58:00.000-07:00

Here is one of the circuit diagram of a power amplifier with the STK1050 single power chip which is supported by several components that make a better sound output. This amplifier is a single output amplifier, so if you want a stereo amplifier, then you must make a similar circuit.

STK-1050 Features:
STK1050 has some features that make it superior and good for your audio amplifier.

Does not require externally connected emitter resistors.
Values of emitter resistors have carefully been reviewed to provide superior characteristics.

Better supply voltage utilization permits designing power supply voltage that are about 0.7V (for RL=4ohms) lower than those required for previous DPP models.
Maximum allowable power consumption for each resistor is 5W or higher, permitting accomodation for all loads.
Peak allowable current is 18A or more, providing an ample margin even for peak currents under when short circuited or similar emergencies.
In particular, maximum output 4 ohms have been enormously improved.

Use of emitter resistors facilitates meeting different safety standards and designing PCBs
Mutual interferences in the high-frequency range caused by layout of externally connected emitter resistors no longer exist. This facilitates lower distortion factors.
Pins are used for emitter resistor output terminals that were not conected in previous DPPs. All other terminals remain uncharged; there is no need for major circuit board changes.

Download STK-1050 datasheet

One Transistor FM Radio

2010-04-01T16:28:00.000-07:00

Thi circuit is very simple with only one transistor. No need additional active components, but if you want to hear the sound louder, just build another amplifier circuit... :)

Part designator	Part description
C1a,C1b	10 pf, 50 v, ceramic disc capacitor
C2	22 pf, 50 v, ceramic disc capacitor
C3	RF tuning capacitor
C4	330 pf, 50 v, ceramic disc capacitor
C5,C8	0.001 uf, 50 v, ceramic disc capacitor
C6	0.22 uf, 50 v, film capacitor
C7	0.0047 uf, 50 v, ceramic disc capacitor
C9	22 uf, 16 v, electrolytic capacitor
D1	TL431AIZ voltage control Zener (shunt regulator)
EPH1	High impedance earphone
L2	22 uh RF choke
Q1	2N4416A JFET transistor
R1	470K, 1/4 w, resistor
R2, R3	1K, 1/4 w, resistor
R4	10K, 1/4 w, resistor
R5	1M, 1/4 w, resistor
R6	100 ohm, 1/4 w, resistor
S1	Small SPST switch
screws for C3	screws for mounting C3 (2 needed)
nylon screw	#4 nylon screw used for tuning C3
battery connector	mini battery snap

More instruction how to build this circuit, visit this page

Portable headphone amplifier circuit

2010-03-28T02:09:00.000-07:00

This is an easy built portable headphone amplifier circuit. You can use this headphone amplifier to amplify your radio receiver, mp3/mp4 player, computer or dvd/cd player. You may connected the input channel directly to those devices.


R1 _______________ 10K
R2 _______________ 100K
R3 _______________ 68K  (see notes)
R4 _______________ 1K5
R5 _______________ 3K3
R6 _______________ 330R
R7 _______________ 4K7
R8 _______________ 2R2
C1 _______________ 1uF 63V
C2 _______________ 100uF 25V
C3 _______________ 470uF 25V
Q1 _______________ BC239C 25V 100mA NPN High-gain Low-noise Transistor
Q2 _______________ BC337 45V 800mA NPN Transistor
Q3 _______________ BC327 45V 800mA PNP Transistor
J1 _______________ Stereo 3mm. Jack socket
SW1 _______________ SPST Switch
B1 _______________ 3V Battery (2xAAA)

R3 value was calculated for headphone impedance up to 300 Ohms. Using 600 Ohms loads or higher, change R3 value to 100K.
Take a note that above circuit only show single channel.

1.2Watt Mini Audio Amplifier Circuit based KA2214

2010-03-17T15:36:00.000-07:00

This mini audio amplifier circuit is based on power IC KA series. This mini amplifier delivers dual audio output (stereo) at 1.2W on each channel.

The KA2214 is a monolithic integrated dual audio power amplifier in a 14-pin plastic dual in line package. It is designed portable audio sets.

Download the KA2214 datasheet for detail features and specifications.

TDA2040 - 20W HI-FI Audio Amplifier

2010-02-27T18:10:00.000-08:00

Here the hi-fi power amplifier circuit which will deliver 20W power output. This amplifier circuit use single power IC TDA2040 and a few external components.

Detailed explanation about this 20W Power Amplifier

Simple FM Radio Receiver Circuit with TDA7021T

2010-02-18T03:21:00.000-08:00

Here the simple FM radio receiver circuit built based single IC TDA7021T.

Component Parts List:

R1 = 8kΩ2
R2 = 10kΩ
R3 = 390Ω
C1,C3 = 10nF
C2,C6,C9,C16 = 100nF
C4 = 33pF
C5 = 25pF trimmer (Murata type TZB4Z250AB10R00)
C7,C10 = 1nF5
C8 = 820pF

C11 = 1nF
C12 = 68pF
C13 = 220pF
C14 = 47μF 10V (Nichicon UWX1A470MCL1GB 5.5mmL chip type)
C15 = 3nF3
L1 = 36nH (4 turns 0.5mm silver-plated wire, inside diameter 4mm; length 7mm)
L2 = 1μH, SMD case 0805 (fres > 300 MHz)
IC1 = TDA7021T (SMD in SO16 case)

Complete explanation, visit this site

AM Receiver circuit with MK484

2010-02-02T20:03:00.000-08:00

This is a AM Receiver with single IC MK484. If your are interested to build this radio circuit, you may buy the kits include the component part list at kitsrus.com.

Part list:

R9, R10_________ 6R8
R6_____________ 100R
R3_____________ 1K
R1_____________ 4K7
R7_____________ 5K6
R4_____________ 10K
R2_____________ 100K
R5_____________ 150K
R8_____________ 820K
Pot_____________ 10K log pot
Coil & ferrite bar set

C7______________ 470p ceramic
C, C4, C5, C6_____ 470nF monoblock
C2______________ 100nF monoblock
C3, C8___________ 100uF electrolytic capacitor
VariCap__________ 60/160 AM tuning cap
D1, D2, D3, D4____ 1N4148 diode
Q1, Q3___________ BC548
Q2______________ BC558
IC1_____________ MK484 AM radio IC TO92
Speaker__________ 0.5 or 1W, 8 ohm speaker

Visit this AM Radio Receiver for more explanation.

Really Simple LED Flasher with LM3909

2010-01-14T15:51:00.000-08:00

This is a very -very easy and simple LED flasher circuit with only needs three components that are: a flasher IC, a LED and a electrolytic capacitor.

Component list:

LED1_________Red LED
C1___________100uf/16V
IC1__________LM3909

Very nice for electronics newbie.. :)

Really Simple Audio Pre-Amplifier

2010-01-01T18:17:00.000-08:00

This pre-amp circuit is very simple. It's just need 1 active component (transistor) to gain the input. You may build similar circuit for your stereo sound system.

schematic diagram:

This easy circuit provides good gain to weak audio signals such as electret microphone. Use it in front of an RF oscillator to make an RF transmitter that’s very sensitive to sound.

2×22W Stereo Car Audio Amplifier schematic diagram

2009-12-25T03:14:00.000-08:00

This is a schematic diagram of stereo audio amplifier for your car. The circuit is powered by a single IC TDA1553 with some external components, this IC will handle your stereo car audio system.

The TDA1553CQ is a monolithic integrated class-B output amplifier in a 13-lead plastic DIL-bent-SIL power package. It contains 2×22 W amplifiers in BTL configuration. The device is primarily developed for car radio applications.

The TDA1553CQ contains two identical amplifiers with differential input stages and can be used for bridge applications. The gain of each amplifier is fixed at 26 dB.

Special features of the device are:

3-state mode switch
· standby: low supply current (<100>

Loudspeaker protection
When a short-circuit to ground occurs, which forces a DC voltage across the loudspeaker of >= V, a built-in protection circuit becomes active and limits the DC voltage across the loudspeaker to <= V. Pin 12 detects the status of the protection circuit (e.g. for diagnostic purposes).

Short-circuit protection
If any output is short-circuited to ground during the standby mode, it becomes impossible to switch the circuit to the mute or operating condition. In this event the supply current will be limited to a few milliamps.

Download the TDA1553CQ datasheet

25W Power Amplifier based IC LM1875

2009-12-14T16:06:00.000-08:00

Short circuit protection, 94dB supply rejection ratio, thermal protection, S/N ratio in excess of 100dB, Open loop gain typically 90dB and 70mA quiescent current, LM1875 is great enough to give you good audio performmance. This power IC will amplify the audio signal up to 30W output power.

Component part list

R1 _____________ 1K
R2 _____________ 1M
R3 _____________ 22K
R4 _____________ 10K
R5 _____________ 180K
R6 _____________ 1R

IC1 ____________ LM1875

C1 _____________ 1uF 50V
C2,6 ___________ 100nF
C3 _____________ 22uF 63V
C4 _____________ 0.22uF
C7,5 ___________ 220uF 50V 

Miscellaneous:
Fuse holder & cover
2 amp fuses

Visit this 25W Power Amplifier page for detail explanation

Simple Gate Alarm

2009-11-28T15:05:00.000-08:00

Here the simple gate alarm circuit that built based on CMOS IC 4093B. With CMOS IC, this circuit must be work with small universal power supply.

IC1a is a fast oscillator, and IC1b a slow oscillator, which are combined through IC1c to emit a high pip-pip-pip warning sound when a gate (or window, etc.) is opened. The circuit is intended not so much to sound like a siren or warning device, but rather to give the impression: "You have been noticed." R1 and D1 may be omitted, and the value of R2 perhaps reduced, to make the Gate Alarm sound more like a warning device. VR1 adjusts the frequency of the sound emitted.

IC1d is a timer which causes the Gate Alarm to emit some 20 to 30 further pips after the gate has been closed again, before it falls silent, as if to say: "I'm more clever than a simple on-off device." Piezo disk S1 may be replaced with a LED if desired, the LED being wired in series with a 1K resistor.

Figure 2 shows how an ordinary reed switch may be converted to close (a "normally closed" switch) when the gate is opened. A continuity tester makes the work easy. Note that many reed switches are delicate, and therefore wires which are soldered to the reed switch should not be flexed at all near the switch. Other types of switches, such as microswitches, may also be used.

Spurce: http://www.zen22142.zen.co.uk/Circuits/Alarm/Galarm.html

High Frequency Waveform Generator schematic

2009-11-13T18:39:00.000-08:00

This is a waveform generator based on IC with wide operating frequency, Maxim MAX038. This IC is able to generate frequency between 0.1Hz to 20MHz.

Here the schematic diagram:

The circuit can be used to generate square wave, triangle, or sine wave by programming the pin inputs (A0:pin 3, A1:pin 4).
- A0 A1 WAVEFORM
- X 1 Sine wave
- 0 0 Square wave
- 1 0 Triangle wave
The frequency can be controlled using current. If we disconnect the 20k RIN from REF (pin 1) and connect it to a DAC, then we can control the frequency using microcontroller or digital interface. We can even control the chip using a quartz crystal (PLL) by controlling the current using a phase comparator output that compares the sync output (pin 14 of MAX038) and a reference clock from quartz crystal oscillator.

Just try to build this circuit... :)

Light Detector

2009-11-08T18:39:00.000-08:00

This is a circuit diagram of light detector. This circuit can be used as a sensor of automatic lamp switch, thic circuit also can be used for anti theft alarm circuit.

Schematic diagram:

Use variable resistor R1 to adjust the light threshold at which the circuit triggers. R1's value is chosen to match the photocells resistance at darkness. The circuit uses a CMOS 4001 IC. Gate U1a acts as the trigger, U1b and c form a latch. S1 to reset the circuit. You may used piezo buzzer or LED as output indicator, you may use both of them.

Active FM Antenna Booster circuit

2009-11-01T04:43:00.000-08:00

This is an active antenna booster. It's mean that the circuit require a power supply to be works.

Input coil L1 consists of four turns of 20SWG enamelled copper wire (slightly space wound) over 5mm diameter former. It is tapped at the first turn from ground lead side. Coil L2 is similar to L1, but has only three turns. Pin configuration of transistor 2SC2570 is shown in the fm antenna booster schematic. Adjust input/output trimmers (VC1/VC2) for maximum gain.

High Quality Intercom circuit

2009-10-22T16:49:00.000-07:00

This is an intercom circuit which use LM380 as the audio amplifier and 2 transistors as the microphone pre amplifier. The sound quality will be good enough with low cost building.

This circuit consists of two identical intercom units. Each unit contains a power supply, microphone preamplifier, audio amplifier and a Push To Talk (PTT) relay circuit. Only 2 wires are required to connect the units together. Due to the low output impedance of the mic preamp, screened cable is not necessary and ordinary 2 core speaker cable, or bell wire may be used.

Detail explanation about this intercom circuit include the PCB layout, please visit this page

Stereo Tone Control circuit

2009-10-17T20:20:00.000-07:00

This is stereo tone control circuit based on IC LM1036. The circuit should be works with supply voltage 9V to 15V DC.

And here the circuit's features:

Wide supply voltage range, 9V to 16V

Large volume control range, 75 dB typical

Tone control, ±15 dB typical

Channel separation, 75 dB typical

Low distortion, 0.06% typical for an input level of 0.3 Vrms

High signal to noise, 80 dB typical for an input level of 0.3 Vrms

Infrared Toggle Switch schematic diagram

2009-10-11T03:56:00.000-07:00

Use this Infrared toggle switch for wireless switching. You need to add IR receiver to electronic device for switching using this circuit.

COMPONENTS


R8________________ 680R
R7, R9____________ 4K7
R1, R2, R4, R6____ 27K
R3________________ 100K
R5________________ 1M
C1, C2, C5________ 470nF
C3, C4, C6________ 47u/16v ecap
IC________________ 4013
Q2, Q3____________ BC548
Q1________________ BC558
D1________________ 1N4148
D2________________ 1N4004
ZD1_______________ Zener diode 5V6
IR receiver module
LED
Miniature relay AZ-SH-112L

All modern IR remote control devices produce a continuous coded stream of pulses at 37.9 kHz when any button on the module is pressed. These IR pulses are detected and decoded by a receiver (your TV, VCR etc.) and the appropriate function activated. In our Kit the coded stream is converted into a single pulse and that single pulse is used to toggle a relay on & off. The coded information is lost. Only the fact that a button was pressed on your remote control unit is detected.

More about this Infrared Toggle Switch, download the manual

"Night Rider" 16 Stage Bi-Directional LED Sequencer circuit

2009-10-05T18:33:00.000-07:00

This bi-directional LED sequencer circuit uses IC CD4516 and IC 74HCT138 as counter and decoder.

Circuit explanation:
The bi-directional sequencer uses a 4 bit binary up/down counter (CD4516) and two "1 of 8 line decoders" (74HC138 or 74HCT138) to generate the popular "Night Rider" display. A Schmitt Trigger oscillator provides the clock signal for the counter and the rate can be adjusted with the 500K pot. Two additional Schmitt Trigger inverters are used as a SET/RESET latch to control the counting direction (up or down). Be sure to use the 74HC14 and not the 74HCT14, the 74HCT14 may not work due to the low TTL input trigger level. When the highest count is reached (1111) the low output at pin 7 sets the latch so that the UP/DOWN input to the counter goes low and causes the counter to begin decrementing. When the lowest count is reached (0000) the latch is reset (high) so that the counter will begin incrementing on the next rising clock edge. The three lowest counter bits (Q0, Q1, Q2) are connected to both decoders in parallel and the highest bit Q3 is used to select the appropriate decoder.

source: http://www.qsl.net/yo5ofh/hobby%20circuits/led_circuits.htm

18W amplifier circuit based on IC HA13118

2009-10-03T16:05:00.000-07:00

Here the 18W audio amplifier circuit which powered by IC HA13118 as the main component.The type of this amplifier is bridge amplifier since the output line does not grounded.

The supply voltage required for this circuit is 8 – 18V DC, at least 1 to 2 Amps. Maximum output power will only be obtained with a power supply of 18V at greater than 2 A, using a 4 ohm speaker. The power supply should be well filtered to reduce mains hum, a regulated supply will reduce noise even further. Extra filtering is unnecessary if operating from a battery supply.

View more explanation about this 18W audio amplifier circuit HERE.

16W Audio Amplifier with LM383 schematic diagram

2009-09-26T17:33:00.000-07:00

Here the 16 watt power audio amplifier circuit powered by dual IC LM383. The single LM383 will amplify the input about 7-8 watt, dual IC should be gain up to 16 watt. You can use wide voltage range 5V - 20V to supply the power IC.

Component list:


U1, U2____________ LM383 power IC
R1, R3____________ 220 Ohm resistor
R2, R4____________ 2.2 Ohm resistor
R5________________ 1 MegaOhm resistor
R6________________ 100k potentiometer
C1, C7____________ 10uf electrolytic capacitor
C2, C5____________ 470uf electrolytic capacitor
C3, C4, C6________ 0.2uf ceramic capacitor
SPKR1_____________ 4 to 8 ohm speaker (up to 8 inches diameter)

10 Watt Amplifier with TDA2009A Schematic Diagram

2009-09-15T19:06:00.000-07:00

This is schematic diagram of 10 watt power audio amplifier using TDA2009A as the main component.

Component list:

R1, R3_________ 1K2 ohm
R2, R4_________ 18 ohm
R5, R6_________ 1 ohm
C1, C2_________ 3u3 50V mini
C3_____________ 22uF 16V
C5_____________ 100uF 35V
C6, C7_________ 220uF 10V
C10, C11_______ 2200uF 35V
C4, C8, C9_____ 100nF
IC_____________ TDA2009A
Heat sink

Download 10 Watt Amplifier with TDA2009A Schematic Diagram in PDF version HERE

Preamp + Tone Control Circuit

2009-09-02T19:44:00.000-07:00

This is a preamp and tone control which combined in in one circuit.
P1 to control the volume level, P2 to control Bass level and P3 to control Treble level.

This is a mono channel circuit, build another equal circuit to make this circuit stereo.

Component:


R1__________220K
R2__________100K
R3__________2K7
R4,R5_______8K2
R6__________4K7
R7,R8,R13___2K2
R9__________2M2
R10,R11_____47K
R12_________33K
R14_________470R
R15_________10K
R16_________3K3

C1,C2,C9____470nF 63V Polyester Capacitors
C3,C4_______47nF 63V Polyester Capacitors
C5,C6_______6n8 63V Polyester Capacitors
C7__________10µF 63V Electrolytic Capacitor
C8,C10______22µF 25V Electrolytic Capacitors
C11_________470µF 25V Electrolytic Capacitor

Q1,Q3_______BC550C 45V 100mA Low noise High gain NPN Transistors
Q2__________2N3819 General-purpose N-Channel FET

100W Power Amplifier for Guitar

2009-08-23T20:16:00.000-07:00

This is a 100 watt audio power amplifier circuit for your guitar. Of course a high quality pre-amp is needed to produce high quality audio output.

You need this schematics..? Go to THIS page and you will find a good pre-amp and power amplifier for your guitar include the complete explanation of its works, and how to build the box.

Low-Ripple Power Supply

2009-08-16T01:55:00.000-07:00

This circuit can be used where a high current is required with a low-ripple voltage (such as in a high-powered class AB amplifier when high-quality reproduction is necessary). Q1, Q1 and R2 can be regarded as a power Darlington transistor. ZD1 and R1 provide a reference voltage at the base of Q1. ZD1 should be chosen thus: ZD1=Vout-1.2 . C2 can be chosen for the degree of smoothness as its value is effectively multiplied by the combined gains of Q1/Q2, if 100uF is chosen for C2, assuming minimum hfe for Q1 and Q2, C=100x15(Q1)x25(Q2)=37,000uF.

DC to DC Converter Multi Output

2009-08-12T01:34:00.000-07:00

This circuit will convert DC volt input +9 to +16 DC Volt.
Output will be:
+28V DC
+15V DC
-5V DC
-12V DC

Simple Touch Switch

2009-08-05T18:53:00.000-07:00

With touch switch, you can turn on and turn on a electronic device. Touch switch don't need mechanical part, so they will not worn out due to mechanical contact. Touch switches can be used in places where regular switches would not last, such as wet or very dusty areas.

Here the schematic diagram:

Component part list:


Part      Total Qty.    Description

C1         1          10uF 16V     Electrolytic Capacitor
R1, R2     2          100K 1/4 Watt Resistor
R3         1          10 Meg 1/4 Watt Resistor
U1         1          4011 CMOS NAND Gate IC
MISC       1          Board, Wire, Socket For U1

Notes:

1. The contacts an be made with just two loops of wire close together, or two squares etched close together on a PC board.

2. When activated, the output of the circuit goes high for about one second. This pulse can be used to drive a relay, transistor, other logic, etc.

3. You can vary the length of the output pulse by using a smaller or larger capacitor for C1.

Sine Wave Generator (1KHz Frequency)

2009-07-27T20:10:00.000-07:00

This is iKHz sine wave generator circuit built based on configuration of inverted Wien bridge (see C1-R3 & C2-R4). R5 and R7 used for output amplutide setting. Set R5 to read 1V RMS on an Audio Millivoltmeter connected to the output with R7 rotated fully clockwise, or to view a sinewave of 2.828V Peak-to-Peak amplitude on the oscilloscope.

Component list:

R1____________5K6  1/4W Resistor
R2____________1K8  1/4W Resistor
R3,R4________15K   1/4W Resistors
R5__________500R   1/2W Trimmer Cermet
R6__________330R   1/4W Resistor
R7__________470R   Linear Potentiometer

C1,C2________10nF  63V Polyester Capacitors
C3__________100µF  25V Electrolytic Capacitor
C4__________470nF  63V Polyester Capacitor

Q1,Q2_______BC238  25V 100mA NPN Transistors
LP1___________12V  40mA Filament Lamp Bulb (See Notes)
J1__________Phono chassis Socket
SW1__________SPST  Slider Switch
B1_____________9V  PP3
Clip for 9V PP3 Battery

Notes:

The bulb must be a low current type (12V 40-50mA or 6V 50mA) in order to obtain good long term stability and low distortion.
Using a bulb differing from specifications may require a change of R6 value to 220 or 150 Ohms to ensure proper circuit's oscillation.
With C1, C2 = 100nF the frequency generated is 100Hz and with C1, C2 = 1nF frequency is 10KHz but R5 requires adjustment.
High gain transistors are preferred for better performance.

Audio Power Indicator

2009-07-27T19:56:00.000-07:00

This is audio level indicator which can be used to measure the audio level output of your amplifier. Simply connect the output of your amplifier to the input of this circuit, then you will know the average value of your amplifier's power.

R1_____________220R  1/2W Resistor
R2,R5,R6,R8____100R  1/4W Resistors
R10,R12,R14____100R  1/4W Resistors
R3_____________220R  1/4W Resistor
R4,R7__________330R  1/2W Resistors
R9_____________560R  1/2W Resistor
R11____________820R  1/2W Resistor
R13______________1K2 1/2W Resistor

D1___________1N4004  400V 1A Diode
D2,D4,D6__BZX79C2V7  2.7V 500mW Zener Diodes
D3,D5,D7,D8,D9,D10   Red LEDs (Any dimension and shape) (See Notes)

Notes:

The output power indicated by each LED must be doubled when 4 Ohms loads are driven.
The circuit can be adapted to suit less powerful amplifiers by reducing the number of LEDs and related voltage dividers.
LEDs of any dimension can be used, but rectangular shaped devices will be more suitable to be compacted in bars or columns.
For a stereo amplifier, two identical circuits are required.

70 Watt MOSFET Audio Amplifier

2009-07-17T18:06:00.000-07:00

This amplifier circuit will give you about 70W output power at 60v supply.
Please visit this page for detail information and characterization

20W Bridge Audio Amplifier based on TDA2005

2009-07-12T17:41:00.000-07:00

This is 20W Bridge Audio Amplifier circuit based on the TDA2005 IC, a class B dual audio amplifier, specifically designed for car radio applications etc.
This circuit require Voltage input 18 VDC and will give you Output power - 20 W, 4 Ω

This is the amplifier kit:

This is the schematic:

To get the schematic diagram, component list and component layout, please download this file

8 LED Audio Level Meter

2009-07-11T17:48:00.000-07:00

This is 8 LED audio level meter circuit diagram. Build based on 2 pieces of op-amp IC LM324. You should use 4 ICs for stereo audio level meter.
Here the schematic:

Running LED

2009-06-28T00:19:00.000-07:00

This is the running LED circuit diagram. The LED will "running" (on) one by one. You can use this circuit for many purpose like motorcycle lamp, running character and much more.

Here the schematic diagram with IC timer 555:

And use this circuit use NAND logic:

Zone Alarm System

2009-06-18T16:43:00.000-07:00

This is the circuit of alarm system with 5 independent zones. Suitable for a small office or home environment. It uses just 3 CMOS IC's and features a timed entry / exit zone, 4 immediate zones and a panic button. There are indicators for each zone a "system armed" indicator.

Zone 1 is a timed zone which must be used as the entry and exit point of the building. Zones 2 - 5 are immediate zones, which will trigger the alarm with no delay. Some RF immunity is provided for long wiring runs by the input capacitors, C1-C5. C7 and R14 also form a transient suppresser. The key switch acts as the Set/Unset and Reset switch. For good security this should be the metal type with a key.

Circuit works:
At switch on, C6 will charge via R11, this acts as the exit delay and is set to around 30 seconds. This can be altered by varying either C6 or R11. Once the timing period has elapsed, LED6 will light, meaning the system is armed. LED6 may be mounted externally (at the bell box for example) and provides visual indication that the system has set. Once set any contact that opens will trigger the alarm, including Zone 1. To prevent triggering the alarm on entry to the building, the concealed re-entry switch must be operated. This will discharge C6 and start the entry timer. The re-entry switch could be a concealed reed switch, located anywhere in a door frame, but invisible to the eye. The panic switch, when pressed, will trigger the alarm when set. Relay contacts RLA1 provide the latch, RLA2 operate the siren or buzzer.

Simple Electronic Buzzer

2009-06-14T17:45:00.000-07:00

This is a simple electronic buzzer circuit diagram. Cheap and easy to build.
The 555 is used as astable multivibrator operating at about 1kHz and produces a shrill noise when switched on. The frequency can be adjusted by varying the 10K resistor. You may change the 10K resistor with variable resistor.