Positive Variable Power Supply circuit

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

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

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

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

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

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

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.

1. Does not require externally connected emitter resistors.
2. 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.

3. Use of emitter resistors facilitates meeting different safety standards and designing PCBs
4. Mutual interferences in the high-frequency range caused by layout of externally connected emitter resistors no longer exist. This facilitates lower distortion factors.
5. 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

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