Using junction FETs, a configurable configuration is achieved for very low frequencies. FETs can be of almost any type and the frequency depends on the capacitors.
We found this circuit in a 2005 documentation. The circuit uses an infrared piezo sensor...
This circuit was found in a 1995 documentation. It deactivates a power supply in the event of a...
This circuit was found in the September 1993 Electronics Now magazine. It is based on the 555 and...