Found in a 1970 documentation, this circuit makes use of 741 operational amplifiers that are common today. Note that the power supply must be symmetrical.
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...