This 80's General Electric circuit is guarded by the noise-guard for operating current. The circuit has an input sensitivity of 3 pA. The font must be symmetrical.
We found this circuit in a 1968 Electronics World. The transistors are from the era and...
There are several manufacturers of the integrated circuit used and it also admits equivalents. The circuit...
This circuit is from 1971 American documentation. Transistors are still common except for 2N2060...