Suggested by Raytheon in 1967 documentation this circuit uses a lightbulb and LDR optical coupler of the time. The transistor determines the maximum current.
This circuit came out in a Popular Electronics from December 1995. It is a double T configuration that...
Found in a 1967 Electronic Design, this circuit can detect pulses as narrow as 0.2 us. Active...
This is the basic configuration of a Colpitts LC oscillator using a CMOS gate. ...