This circuit was found in a 1967 General Electric documentation. The components are from that time. The tunnel diode is difficult to obtain today.
This circuit is from 1989 documentation. The circuit is based on CMOS technology and the displays are...
This bridge amplifier for the car was found in an American documentation from the 90's. It can be...
This amplifier for relay or shield was found in Radio Electronics magazine from November 1961. The...