This is an old test circuit for integrated TTL counters, feeding a Nixie tube, common at the time. The circuit is from the 90's, not being given the power supply.
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...