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 power source, obtained in a 1973 publication, suggests the use of partially burned germanium...
This circuit was obtained from an Electronic Design from 1964. Transistors admit modern...
The circuit is from the 1994 National Semiconductor Linear Applications Handbook but can be...