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 can be used in decoration or to draw attention, in a “fake” assembly for example. What he...
This filter was found in Exar documentation from the 1980s. The circuit has an attenuation of 60 dB at the...
This windshield wiper timer was obtained in an 80's Hands On. The transistor can be the BC548 and...