This circuit uses a General Electric coupler from the time of the publication in the 1980s. Equivalent SCR can be used.
In this circuit the gain decreases as the input signal intensity increases. The circuit is from a...
This circuit was found in an American 1980s documentation. Dual FETs can be replaced by single...
September 2016 - Mouser Electgronics already has in stock the new moisture digital sensor HDC1010...