Simple Intercom Circuit with Transistors

This is a 2-station simple intercom circuit build based on transistors part and using common 8R mini speakers. The speaker works as microphone and generate sound, so there is no need microphone for this intercom. The "press-to-talk" switches should have a spring-return so the intercom can never be left ON, push on switch can be used for this kind of task.

Dynamic Mic Amplifier (To Use Speaker as Microphone)

This is the circuit diagram of dynamic mic amplifier. This simple and easy built circuit can be used as a subtitute of an electret microphone. It will turn an ordinary mini speaker to become a pretty sensitive microphone.

Simple Audio Booster

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.

Cricket Chirping Sound Generator

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.

19W Power Amplifier based LA4440

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.

15W Audio Amplifier with STK055

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.

Surround Sound Processor Circuit

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.

Mic Preamplifier Circuit based TLC251

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.

Stereo Tube Power Amplifier Schematic

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.

12 LED VU Meter Circuit

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.

2-Way Active Crossover Circuit

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].

Stereo PLL FM Transmitter based BH1417

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.

80W Power Amplifier Circuit

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.

CMoy Headphone Amplifier Circuit

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.

Simple LM358 Mic Preamplifier

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

Echo Chamber Schematic

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. :)

Passive Surround Audio Circuit

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

14W Audio Amplifier Circuit

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

50W Amplifier Circuit based ICL8063 + 2N3055

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

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