This 1969 Mullar circuit appears elsewhere on this site. The circuit uses germanium diodes and the indicator is microammeter with zero in the center of the scale.
We found this circuit in a year 2000 documentation. It must be powered by a voltage of 5 V as it...
This circuit was found in the February 1990 issue of Radio Electronics magazine. The circuit uses...
Voltage comparators, such as those in the LM139/239/339 series, consist of devices that can be...