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).
We found this circuit in an American publication from the 90s. The transistors must be provided with...
The critical components of this project from a 1978 publication are the transformers, which can be...
September 2017 - Mouser Electronics already has the AP431S adjustable regulator from Diodes...