How to reduce 170V to 140V @1A?

Discussion in 'General Electronics Chat' started by HermanB, Apr 19, 2016.

  1. HermanB

    Thread Starter New Member

    Apr 18, 2016
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    My problem is that I have about 170 volts as source, and need to drop it to about 140 V, while the load will draw near 1 amp. Is a voltage divider practical at these values?
     
  2. MrChips

    Moderator

    Oct 2, 2009
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  3. MrChips

    Moderator

    Oct 2, 2009
    12,440
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    So you need to drop 30V @1A = 30W

    Apply Ohm's Law I=V/R
    Power = I x V

    Hence you will need a 30Ω resistor rated for more than 30W, i.e. about 50-100W
    Think of a 30v, 30W light bulb.
    That is how hot it is going to get.

    Three 12v 15W light bulbs in series will do it.

    If this is mains AC, use a step-down transformer.
     
  4. HermanB

    Thread Starter New Member

    Apr 18, 2016
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  5. HermanB

    Thread Starter New Member

    Apr 18, 2016
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  6. HermanB

    Thread Starter New Member

    Apr 18, 2016
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    Thanks again. This goes a long way towards solving the issue, now practical trials will have to ensue. My theoretical knowledge is a bit limited/rusted, being an old-timer!
     
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