This alarm is either activated or triggered after a certain amount of time, giving the owner time to exit or enter and disarm it. The circuit is from a Radio Electronics from April 1975.
Found in a National Semiconductor manual from the 1980s, this circuit uses a voltage comparator of the...
This very low power amplifier is designed by Amperex for hearing aids. It is based on TAA370 which is...
Found in English documentation from the 1980s, this circuit can use any germanium diode. The...