Using an LDR as a sensor, this circuit is from the Radio Electronics magazine of December 1984. The operational amplifier is the 741 and the source must be symmetrical.
Using a sensor from the time, this circuit was found in the 1992 Radio Electronics Handbook...
This TTL oscillator uses a ceramic resonator as a frequency fixing element. The resonator is found...
The circuit below uses common JFET transistors, which can be the BF245 or MPF102 amplifying video...