This timer circuit was found in a 1980s American documentation. Transistors and SCR support modern equivalents. The circuit was originally designed to control a motor.
This circuit is from an English publication of 1982. The bipolar transistor can be a BC548 and the...
This circuit of an Electronics Hobbyists Handbook uses a different configuration for a triac. The...
This circuit for low frequency signals was found in a publication by Gernsback from 1960. The...