This circuit is from a July 1970 Radio Electronics magazine. The sensors are metal probes. The 18 V power source must be isolated from the mains.
We found this circuit in a publication on operational amplifiers from 1978. The circuit is made...
This circuit allows the detection of RF signals using the lowest range of direct currents of a...
This circuit was found in the Radio Electronics magazine of May 1990. The supply voltage depends on...