Using 555 integrated circuits, this alarm circuit was found in a 90s American documentation. The signal must be applied to a good audio amplifier.
This complex circuit with many digital components measures inductances in 6 ranges ranging from 100...
This circuit was found in old publication from 1958. The circuit uses germanium transistor, common in...
Some old analog multimeters use a 22.5 V battery for high resistance measures. These batteries can no...