This circuit is based on the light comparison of two LDR sensors. We found it in a 90s Popular Electronics. The transistor must be according to the indicator or load being driven.
We found this circuit in an American publication from the 1990s. The circuit has a Darlington...
The sensor for this alarm is an LDR and it consists of an oscillator that goes into action when...
This circuit was found in a computer publication from the 1970s. The transistors can be the BD135...