Audio plug connected to needle

Discussion in 'General Electronics Chat' started by jamus, Apr 25, 2014.

  1. jamus

    Thread Starter Member

    Feb 11, 2013
    53
    0
    I was at the thrift shop today and I found a two contact phone connector attached to about three inches of cable on the end of which was a four inch long needle. What is it for?

    I was quite curious, but I didn't buy it. Here is a drawing I made of it:
     
  2. #12

    Expert

    Nov 30, 2010
    16,320
    6,818
    I use mine to penetrate the insulation of wires or corrosion on connectors...except I made mine out of a .05 inch Allen wrench ground to a point and installed in a standard probe handle.
     
  3. ErnieHorning

    Member

    Apr 17, 2014
    67
    17
    From your drawing, it looks like a temperature probe for a microwave oven. It's just a thermistor.

    [​IMG]
     
    jamus and shortbus like this.
  4. #12

    Expert

    Nov 30, 2010
    16,320
    6,818
    I got stuck on the word, "needle" and thought it was a very thin, sharp point.
     
  5. ErnieHorning

    Member

    Apr 17, 2014
    67
    17
    I’ve never been able to think of much hobbyist use for this type of thermistor.I have used these for one use though.

    Normally a thermistor is used just to measure temperature; the resistance changes relive to temperature.Most have a negative temperature coefficient (NTC), meaning that the resistance decreases with increasing temperature. Even though they don’t have a linear change, there are well known formulas that can linearize this pretty well.

    Because a thermistor has resistance, you can pass current through it and it will heat up to.If you control this through a microcontroller, you can use it to measure the level of a liquid.Heat it up in open air; it will heat up relatively quickly.Heat it up in while immersed in a liquid; it will heat up in a much longer time.

    Because these sensors are incased a stainless tube, they work well for nearly any liquid; even acid.
     
    PackratKing likes this.
Loading...