For many people winter is approaching and the temperature is going down. But, it also is a time when the air will hold less moisture, and dry air breeds static electricity. Or, more accurately, dry air does not allow static electricity to dissipate as easily as moist air. So, this seems like a good time to share an easy to make static electricity detector. I have made this circuit many times over the years and it is fun to use and it demonstrates some of the characteristics common to field effect transistors. (FET's). They act as switches and are very sensitive to static charges in the air. In fact, this circuit can detect a negative charge at over 5 feet when the relative humidity is low. There is also an explanation of the triboelectric series in the attached links.There are only two parts needed and they are available at Radio Shack as well as most electronic suppliers. The first is the FET, Radio Shack #276-2062, and a red light emitting diode, (LED) #276-041. And it is powered by a 9 volt battery.The circuit can be soldered, connected with alligator clips, or as shown in the video, a homemade printed circuit board is used. After the video, links will be provided with really excellent explanations and use of the detector. Also some explanatory photos:
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