This circuit was found in an Australian publication from 1991. It is a transmitter that transmits a signal when it detects moisture. The range is on the order of a few tens of meters.
The purpose of this circuit is to allow common analog multimeters to measure low resistances, on...
This is the circuit of the N-201 commercial multimeter of the analog type. The circuit is from...
This receiver was found in the Radio Electronics magazine of March 1953. It tunes to the medium wave...