We found this circuit in the Encyclopedia of Electronic Circuits Volume 5 from 1995. It uses a 3-terminal transducer from the time. The circuit is triggered by light.
This amplifier circuit with gain between 0 and 96 was found in the December 1983 issue of Radio...
This power step drains just 3.5 mA from the battery and can provide good playback on a 4-ohm...
This sophisticated circuit with a low, medium, and high treble filter is from 1990 documentation. The...