Found in documentation from the 1990s, it uses a sound effects integrated circuit, the SN7677 from Texas Instruments. Unusual component these days.
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...