Automatic 9V Battery Charger

This is the scheme diagram of automatic 9V battery charger circuit, the parts list provided below the schematic image. The circuit was designed by Jan Hamer, translated by Tony Van Roon dan republished in this circuit diagram site. The circuit details are based on european standards: 120E, 150E, etc. The ‘E’ just stands for Ohms… Read More »

A/B Box Switch 2 Inputs 1 Output with Dual Op-Amps

This is a A/B Box switch pedal schematic with two inputs and one output and featured with dual operational amplifier modules. This circuit was designed by Rick Barker. This A/B Box effect was originally designed for switching between different harmonica mics. This A/B Box featured low noise dual preamp for better performance.

Theremin Music Instrument

The following diagram is the Theremin music instrument effect. A guitar or instrument amplifier is an ideal companion unit for the theremin; either one allows bass or treble boost, as desired, and fuzz (distortion) or reverberation (if these features are incorporated in the amplifier”s circuit). Simply provide a suitable cable plug and connect the theremin”s… Read More »

4W Audio Amplifier based TDA1013B

The following diagram is the circuit diagram of simple 4W audio amplifier based TDA1013B. The amplifier is based on integrated audio amplifier chip, TDA1013B which is able to gained the audio power output up to 4W at 8 ohm loads. Wide supply voltage range can be used for this circuit from 10VDC to 40VDC. Recommended… Read More »

Six LED Stereo VU Display

The following image is the scheme diagram of six LED stereo VU display circuit which build using Dot/Bar Display Driver IC LM3915. This VU display should be connected before amplifier module circuit. You may connect this circuit at pre-amp output, tone control input/output or equaliser input/output. This circuit powered with 12V DC supply. About LM3915:… Read More »

Tone Detector / Sound Activated Switch

The following circuit diagrams are tone detector circuit diagrams which also known as sound activated switch circuit. Actually, these circuits  use microntroller for switching because the circuits were designed for robot start up activation. But you can build switching module using relay. You may make a trial to use this circuit for other applications such… Read More »

Car Transistor Ignition

This transistor ignition circuit give your car to have better starting and smoother running, particularly at very high and very low RPM. Lower fuel consumption, less pollution, lower servicing costs. Drive economically, drive electronically. Only for petrol/gasoline engines. This circuit will reduce breaker point wear and provide cleaner spark. Circuit diagram: Wiring diagram with the… Read More »