This circuit was found in a Popular Electronics from the 90s. It is based on components still common today and an optical coupler for the triac. The sensor is a thermistor.
This circuit was found in RCA documentation from the 1960s. It supplies two voltages from a single...
This circuit was obtained in a 1978 publication. The SCR may be the TIC106. What it does is act as a...
Found in a 1990s US publication, this alarm circuit detects when a light beam is interrupted. Optical...