Nichrome Wire Winding

Discussion in 'General Electronics Chat' started by R!f@@, Mar 2, 2011.

  1. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
    I am going to buy some nichrome wires.

    I am going to use these wires to make dummy loads.
    Resistance will be like 2Ω, to say around 16Ω.
    I assume these will handle plenty of power without breaking when wounded on things like cement and dipped in water...right? problem lies stray L & C.
    How can I avoid them bugger's and wind a Resistor.

    Can any on show me a way to do this..:D
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    Depending on your power requirements, you could also consider using electric water heater elements. They are reasonably priced (here at least), and are covered in an insulated metal tube. With several of them and some switches, you can vary the load resistance easily. We mounted them in a ventilated box for air cooling.
  3. ifixit

    AAC Fanatic!

    Nov 20, 2008
    Hi R!f@@,

    Here is one DIY idea...
    Wind your resistors in two layers and connect in parallel. If you need a resistance of 2 Ω then the resistance of each layer should be 4 Ω and connected in parallel to get a total of 2 Ω. Wind one layer counterclockwise and the other clockwise in order to cancel the inductance. Each turn of each layer should be separated by twice the diameter of the wire to increase the self-resonance frequency away form the operational frequency.

    Happy winding,
    PackratKing likes this.
  4. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    Fold the wire in half. wind it in a single layer. Leave plenty of space between the wraps as nichrome wire will expand greatly if enough current passes to heat it very much.

  5. someonesdad

    Senior Member

    Jul 7, 2009
    You can look up the Ayrton-Perry type of winding (similar topologically to ifixit's suggestion). If the wire is insulated, then an easier method is to just fold the wire at the midpoint and bring the ends together. Then wind around a form. I tried this a month or two ago and it reduced the measured inductance by a factor of 10.

    By the way, sometimes Nichrome can be expensive. If you can find some type K thermocouple wire, the Chromel in it is an alloy nearly the same as Nichrome. I salvaged a pretty good size roll of type K TC wire and use it for a Nichrome substitute sometimes.

    Personally, I like beenthere's solution better, as it would be quick to hook up and heater elements are easy to obtain. Old stove heater elements would work too. Or, you can find a pot like the one in the picture -- it works pretty well as a dummy load for low frequency stuff... :p
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