This well-known circuit version of the siren was obtained in a Colectro Handbook from the 70s. The transistors are of general use, with Q2 being a BD136 for greater power with power from 6 to 12 V.
This counter performs the same function as the 4020, but includes an internal oscillator. The...
This circuit was obtained in a Popular Electronics of the 90s. It against a kitchen hood based on...
This circuit is from a 1980s Signetics documentation. The circuit separates the modulation signal from a...