Found in a 1964 Electronic Design, this circuit uses a common LDR and transistors from that time. The relay is a high sensitivity type.
This circuit is based on an operational window comparator. We found it in a documentation from the...
The original application of this 1967 Ferranti circuit can be changed so that it functions as a pass...
This variable timing circuit was found in 1964 General Electric documentation. Circuit uses PUTs...