This circuit is from a Radio Electronics from February 1959. The circuit has a speaker output and good sensitivity. Power is supplied from a 9 V battery.
This VCO makes use of an RC4558 which is an operational amplifier with characteristics close to...
This circuit can operate with different voltages, depending on the zener used. We found it in a...
This circuit can be used in the car to control the windscreen wipper or with other appliances at...