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.
Found in an English documentation from 1989, this font uses current components. Rectifier bridges can...
This sensor circuit for currents of the order of nanoamperes was found in an American...
This TTL sequential flasher circuit was found in the January 1981 issue of Radio Electronics...