Obtained in a 1968 Electronics World, this circuit uses transistors from the time and the sensor is a common LDR. The component values are for scales from 0.01 to 100 foot-candle.
This series sensor circuit is from 1995 Popular Electronics. The circuit can use any SCR and the...
The circuit is a multivibrator version using two NPN general purpose transistor. This circuit can...
This circuit is from 1976 documentation. It uses the operational amplifier 709 which is no longer...