This buzzer trigger can be used for small alarms. We find it in an 80’s American documentation. The supply can be done with voltages from 3 to 18 V.
The circuit is from an English publication from 1970, but it can be assembled with more modern...
This astable circuit has a different configuration. We found it in a Radio Electronics from...
This circuit was found in a 1975 documentation. The SCR can be of any type and in this case, we...