This alarm goes off if someone leaves a door open. We found it in the Encyclopedia of Electronic Circuits Volume 5 from 1995. The circuit uses components that are still common today.
This circuit was found in a 1980s US publication. There may be some difficulty in obtaining the...
The circuit shown is from the Motorola Linear Databook of 1990. In the example, the components are for the...
Ideal for benchtop use, this dual-band circuit was obtained from the 1995 Electronics Now...