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.

FM Receiver Antenna Amplifier

This is the active FM receiver antenna amplifier, used to boost the FM signal catch by the antenna, you may call circuit “FM antenna booster”. By working with only a small handfull of parts you can assembled this kind of reliable FM amplifier circuit. It runs with only 1 UHF/VHF type transistor, MFE201. This amplifier… Read More »

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 »

4 Band Equalizer

The following scheme diagram is the four 4 band equalizer circuit. Equalizer device is generally used to improve the fidelity of sound, to emphasize certain instruments, to remove undesired noises, or to create completely new and different timbres. This circuit operated with 12VDC symmetrical / dual polarity power supply. Power supply circuit provided on above… Read More »