We found this circuit in the 1983 Radio Electronics Special projects magazine. The components are common, and the circuit drives a relay. The power supply must be isolated.
This is a bridge for the measurement of low value resistances and high values too. The circuit...
We found this circuit in a publication for radio amateurs of 1976. The operational amplifier is a...
This circuit, with two operationals, was obtained from an old American publication. Operational...