This circuit was found in a 1985 documentation. It provides an audiovisual indication of the presence of moisture or water in the sensor. The circuit can be powered by voltages from 6 to 9 V.
This 70 kHz oscillator is used to erase tapes in pre-recording. The circuit is from 1968 General...
We found this circuit in an old documentation for hams. In it we have the way to use a varicap to...
This sensitive touch circuit that triggers an oscillator uses only transistors. The circuit is...