We found this circuit in an old documentation, but it is still current. General purpose transistors can be used, and the SCR can be the TIC106. The bell is a transducer with an oscillator (buzzer).
This amplifier for distributing audio signals appears in other articles on this website and even...
This circuit was found in a 1964 MOSFET applications manual. The circuit uses period general...
This circuit works only with incandescent lamps, timing its activation at intervals that depend on C1....