static electricity detector not working

Discussion in 'General Electronics Chat' started by arnab321, Jan 16, 2008.

  1. arnab321

    Thread Starter New Member

    Jan 16, 2008
    go to

    i made the above circuit, but in place on 2n3819, i used bf245(this is also a N channel JFET).

    i bought two sets of transistors, used both, one by one, sure that both of them cannot be damaged, yet it didnt work. i connected my galvanometer in place of the led, still, it showed no deflection when i bought near the comb........any solution?
  2. Audioguru


    Dec 20, 2007
    The comb must be non-conduting plastic and your hair must be clean and dry. The air must have low humidity. The gate of the Jfet and the 100k resistor must not be on a circuit board or plugged into a breadboard but must be in the air without touching anything.

    The LED will be turned on and when you comb your hair it will flicker and maybe will turn off because the comb will become negative.

    Of course the parts must not be connected backwards.
  3. beenthere

    Retired Moderator

    Apr 20, 2004
    An independant check of the charge on the comb may be done with a water tap turned on so a very thin stream of water flows. Run the comb through you hair and then hold it close to the stream of water. If there is a charge on the comb, the water stream will deflect towards the comb.