This detector with ultra-low deviation was found in an American documentation from the 90s. Operational amplifiers are from that time. The power supply must be symmetrical.
This circuit is from 1990 documentation. It uses a bridge with LEDs and the potentiometer must be...
This circuit has the spark duration controlled by a 555 timer. The circuit was found in the 1990...
Taking Raytheon's 3900 integrated circuits as an example, uncommon today, this circuit can be used...