Found in a 1965 CQ magazine, this circuit uses period components. The unijunction transistor can be a 2N2646 and the relay has voltage according to the supply.
This circuit was obtained in a 1982 English magazine. This circuit can be used both as a simple...
This sensor triggers an oscillator emitting sound when a magnet is approached by a reed switch....
Suggested by Burr Brown in 1969 documentation, this circuit makes use of an integrated component...