This circuit uses a 555 (according to the diagram) to generate 50 ms tone bursts at a frequency of 1.5 kHz. The circuit is from an 80's Electronic Design.
We found this circuit in the National Semiconductor FETDatabook of 1977. The signal has an...
This circuit was obtained from an English magazine from 1979, but it can be easily assembled today...
September 2016 - Mouser Electgronics already has in stock the new moisture digital sensor HDC1010...