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 two-tone alarm siren was found in the January 1975 issue of Radio Electronics magazine. The...
We found this peak audio indicator in a 1980 publication. The M1 indicator can be 200 uA with the...
This is a traditional complementary-output transistor amplifier sourcing 2 to 4 watts to a 4 ohm...