This 4-transistor amplifier can work from 4.5 or 6 V power supplies. We found it in a Mullard transistors manual from 1960. The transistors are from the time.
This circuit from an old Argentine publication shows how it is possible to use a tunnel diode in a...
To invert the rotation of a motor by changing the levels of an Arduino output or another...
This ultra-low distortion driver was found in 80's Analog Devices documentation. The circuit has a...