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.
This car turn signal circuit was found in the April 1969 issue of Radio Electronics magazine. The...
We found this small amplifier in a 1973 technical publication. The critical components are the...
We found this circuit in a Radio Electronics from October 1960. The circuit uses just one...