This is a battery powered 3W power amplifier using germanium transistors. The circuit is from an English documentation from 1967. The transistors are from the time.
We found this circuit in a 1980s publication for amateur radio. It consists of an audio amplifier...
This preamplifier for high impedance microphone is designed to make a good addition to the speaked word...
This zero crossing detector is of the 1993 Motorola Linear Interface ICs. The source is...