Found in American documentation from 1969, this circuit operates in the frequency range 10 to 150 Hz providing signals as shown in the diagram itself.
September 2016 - Mouser Electronics is providing new ultraviolet LEDs VLMU1610 of Vishay suitable...
September 2016 - Mouser Electgronics already has in stock the new moisture digital sensor HDC1010...
August 2016 –It can be purchased from Mouser Electronics the new converters BD7F100 and BD7F200...