This circuit was obtained from an 80's Electronic Engineering. The circuit detects ice formation by triggering a warning light. The operational amplifier is of the time.
The transistors of this circuit found in a 1965 magazine can be the BC558 and the sensitive 12 V x...
This circuit is from a Radio Electronics from December 1964. The components are from the time and...
Found in General Electric's 1969 documentation, this circuit uses two Foto Darlingtons to control...