This circuit was found in the September 1972 issue of Radio Electronics magazine. The circuit uses an operational amplifier of the time and a symmetrical 9 V source.
This circuit is from Motorola's Linear Interface ICs from 1993. The MC1723 is the equivalent of...
T This circuit produces an audible signal when someone touches the sensor, or even approaches. The...
We found this circuit in a 1968 Electronics World. The transistors are from the era and...