This old circuit, from the 80's, uses an integrated circuit that is uncommon today. The circuit is intended for loads controlled by triac and the resistors depend on the desired control.
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...