This circuit has more power than the previous one, since it includes a powerful transistorized stage. The circuit is from Radio Electronics from July 1985. It includes the power supply.
This circuit uses reed switches as sensors. We found it in a 1992 documentation. A float at a...
One of the problems with analog multimeters is the non-linearity of the resistance scale. This...
I found this circuit in an old English magazine from 1979, but it can be easily assembled with...