This circuit was found in the July 1978 issue of Radio Electronics magazine. The circuit uses a common digital voltmeter as the indicator. The sensors are integrated circuits of the time.
This circuit was obtained from a Poptronics in June 2001. The magazine no longer exists, but the...
We find this circuit in a 1980s documentation. The circuit uses uncommon components today which can...
This circuit has a very high input impedance and a very low output impedance. We found it on a...