This circuit provides a delay for the activation of an alarm, giving the owner time to leave the premises. The circuit is from the 1995 Encyclopedia of Electronic Circuits Volume 5.
According to the author of this project, from a documentation on espionage from the 1980s, this...
This circuit suggested by Siemens can provide time intervals for triggering values that are given...
This circuit generates a good-intensity 1 kHz rectangular signal. The circuit is from Electronics Now...