This is the receiver from the previous alarm system. The circuit is from Radio Electronics, April 1989, and has an LDR as the sensor. Optical devices should be used to improve performance.
This didactic circuit was found in a 2001 documentation. It presents the result of programming in binary...
This VFO circuit generates signals from 2 Hz to 50 Hz. We found it in Popular Electronics from...
This circuit can be used as a buzzer from 3 different locations, allowing you to identify where it went...