Found in an old English publication, this circuit applies to the 240 V network, but can be changed to lower voltages. Transistors are mostly general-purpose, admitting modern equivalents.
Found in an Electronic Design from the 90's, this circuit uses an SCR according to the controlled power....
This circuit was found in an English publication from 1967. The circuit is for listening on a...
This is the traditional configuration of an OR gate using a voltage comparator, but it can also be...