We found this circuit in the June 1984 issue of Radio Electronics magazine. The circuit uses an integrated circuit that is not very common today.
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...