In this circuit the triac conducts when switch S1 is opened. We found it in the October 1987 Radio Electronics magazine. The triac is controlled according to the load.
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...