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 circuit can be found in a 1970 Motorola documentation. The circuit can be implemented with general...
This precision reference circuit was found in documentation from the 1980s. It applies to other...
Other series comparators such as the LM239 and LM339 can be used in this oscillator circuit. The...