This circuit was found in a 1967 General Electric documentation. The components are from that time. The tunnel diode is difficult to obtain today.
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...