This circuit was found in Mullard's transistor application manual from 1960. More modern transistors can be used. The zener diodes used have the indicated voltages.
This circuit is from Linear Technology 2005 documentation. The circuit is based on company...
This circuit was found in the Optoelctronics Sourcebook from Texas Instruments. The circuit has a...
This traditional version of timer was found in an old English publication. The relay must be of a...