Found in documentation from the 1990s, this circuit drives an SCR with a delay that depends on C1 and can be set to R1. The load depends on the SCR.
A circuit for controlling the temperature of a heating element was found in a Mullard transistor manual...
We found this circuit in a 1992 Popular Electronics. The circuit has an optical sensor with LED...
I found this circuit in an old English magazine from 1979, but it can be easily assembled with...