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 circuit was obtained in a 1967’s EEE. Transistors and integrated circuits can be replaced by...
This source, found in a 1991 publication, was originally designed to operate with the CB18736E, an alarm...
This circuit is from Motorola's 1990 Linear Databook. We can implement it with other operational...