This circuit was found in an 80's EDN. The circuit uses a current common CMOS, the 4093 powering an LED. Trigger adjustment is done in a trimpot.
This circuit was found in a 1968 Motorola documentation. The circuit can be implemented with...
This circuit was found in the June 1995 Electroics Now magazine. The relay should be a sensitive type...
This circuit was obtained from an English magazine from 1977. The magazine no longer exists, but...