This 80's circuit uses a germanium transistor like the AC121. The circuit has an output transformer of the type found on many transistor radios of the time.
The purpose of this circuit is to alternately activate a two-tone horn with low sound and a horn...
In the figure we show how to trigger a triac for a continuous voltage of the order of 2 V,...
This high-Q low-pass filter was found in the October 1990 issue of Radio Electronics magazine. The...