Make my own Wire Wound Resistor

Discussion in 'General Electronics Chat' started by Gdrumm, Feb 11, 2015.

  1. Gdrumm

    Thread Starter Distinguished Member

    Aug 29, 2008
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    I saw a better way to discharge a MWO high voltage capacitor that involves using a 150k ohm 25 watt wire wound resistor.

    I have several smaller ceramic resistors, would one of those work? Could I put two or three of them in series to make one?

    I used to have a wire wound resistor laying around, and now I can't find it.

    Might I be able to make one for myself?

    I also have a lot of electronic junk laying around, like PCs, Powerr Supplies, Stereo stuff, etc., what types of in home devices might have one that size?

    Thanks,
    Gary
     
  2. cmartinez

    AAC Fanatic!

    Jan 17, 2007
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    You could assemble a network of resistors in series and/or in parallel that would give you the required resistance and power.
     
  3. wayneh

    Expert

    Sep 9, 2010
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    Yes, and this spreads out the heat so that the rating can be smaller. But each still needs to be rated to ~2X of I^2•R.
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Several sources depending on what wattage and resistance, there are Electric furnace elements which can be tailored, also Nichrome wire can be had cheap in the internet, and S.S. Mig welding wire.
    150k is fairly high for a DIY version!
    Max.
     
  5. Gdrumm

    Thread Starter Distinguished Member

    Aug 29, 2008
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    Thanks everyone,
    Gary
     
  6. cmartinez

    AAC Fanatic!

    Jan 17, 2007
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    You may find this interesting.

    Power rating: 450...1000 W
    Dimensions: 126 x 300...126 x 600 mm
    Resistance range: 2R0...1M0
    Tolerance: ±5%... ±10%
     
  7. ian field

    Distinguished Member

    Oct 27, 2012
    4,413
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    A while back I constructed a crude voltage breakdown tester that runs from the mains and has a decent sized pair of electrolytics in a voltage doubling bridge rectifier arrangement - the problem was how to make it safe between tests, by dumping the charge in the 2 electrolytics.

    A shorting switch seemed obvious - until the first actuation blew the contacts away.

    The replacement shorting switch was wired in series with a NTC inrush limiting thermistor, it starts off with a relatively high resistance at room temperature and doesn't sputter the switch contacts, as the charge in the capacitors send current through the NTC; it warms up and reduces to a lower resistance and discharges the capacitors rapidly to zero.
     
  8. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    a standard size resistor in the 5-10 Meg Ohm range could be attached permenantly and just be a 'bleed' resistor. a few min. after power off and the cap is discharged.
     
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