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.
We found this circuit in a 1998 documentation. It is based entirely on relays that must have...
This traditional complementary symmetry circuit provides 20 W of rms power at a load of 8 ohms...
Assembled with SMD components this circuit can be very small. The range is a few tens of meters. We...