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.
This circuit is from Radio Electronics from the 90s. It supplies a voltage between 800 V and 2 000...
This audio detector circuit can be used for cable identification. We found it in a Popular...
This highly sensitive circuit was found in a 1967 General Electric SCR manual. Equivalent...