Found in a 1980s documentation, this circuit uses transistors from that time. Modern equivalents can be used. The alarm is a piezoelectric buzzer with na included oscillator.
This circuit is based on an integrated TIPL62 from Texas Instruments, uncommon today and an...
This circuit appears in other articles and suggestions for circuits in this section from other...
This circuit was obtained from an Electronic Design from the 90's. The circuit generates signals at a...