This circuit is from a Radio Electronics from April 1965. It uses an incandescent lamp, and the sensor is an LDR. Component values have not been indicated but can be deduced. The capacitor determines the frequency.

This circuit is from a Radio Electronics from April 1965. It uses an incandescent lamp, and the sensor is an LDR. Component values have not been indicated but can be deduced. The capacitor determines the frequency.