We found this circuit in a Hands-On Electroncs from the 90s. The circuit uses an LED indicator. Diodes are general purpose types.
This old fashioned amplifier can source some watts to a low impedance loudspeaker. The circuit...
This circuit is from a Radio Electronics from September 1969. The integrated circuit used is one...
This CMOS circuit is re-triggerable. It was found in the April 1988 issue of Radio Electronics...