DIY Resistive Load bank

Discussion in 'General Electronics Chat' started by ak2011, Oct 24, 2011.

  1. ak2011

    Thread Starter New Member

    Oct 24, 2011
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    Would also like some help on creating a load bank. Haven't done one before...but would like to create an electronic load bank that I can switch with logic (transistor-based??)

    I have two DC/DC bricks producing 12VDC and 5VDC. I want to be able to load each rail from 0.5A to 5A, in 100mA steps. Any help is greatly appreciated...

    Thanks!
     
  2. chrisw1990

    Active Member

    Oct 22, 2011
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    ak2011 likes this.
  3. ak2011

    Thread Starter New Member

    Oct 24, 2011
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    thanks, this should work. maybe i can use a digital pot to electronically control the current load.

    thanks again
     
  4. ak2011

    Thread Starter New Member

    Oct 24, 2011
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    So I modified another example I found online, and simulated it (see attachment)...seems to work. Seems too simple...any suggestions on add-ons? (e.g. protection diodes, etc). This circuit can load the DUT with up ~12A
     
  5. chrisw1990

    Active Member

    Oct 22, 2011
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    yeh not a bad idea using the digital pot, how you then provide feedback to the IC controlling the pot is up to you, one thing though, why use a regulator for the power? with only 100mA perhaps a zener would be more appropriate - like the design i showed you? whats the 12V source you're using?
    also, have you calculated the current sense resistor? or borrowed one of another design?
     
  6. ak2011

    Thread Starter New Member

    Oct 24, 2011
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    Zener is probably a good idea instead of the LDO...the 12V supply will be from an ATX supply

    Current sense resistor was borrowed from another design. I like the 0.1 (if I can find one) to minimize power dissipation (a higher value resistor would mean more power)
     
  7. chrisw1990

    Active Member

    Oct 22, 2011
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    also, unless you only have the lm324 (while im pondering over it) why not use an alternative single opamp? less waste and potentially less cost, though a dual is probably going to cost less =]
    anddd maybe.. might be worth putting a back up passive overcurrent system in place?
    just in case the digital side fails?
     
  8. ak2011

    Thread Starter New Member

    Oct 24, 2011
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    So i incorporated the current limit....this circuit will limit the current to abt 12A; might do a bit fine tuning, but i think it's good for now

    other changes are the voltage reference and op-amp.

    what do you think?
     
  9. chrisw1990

    Active Member

    Oct 22, 2011
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    nice, i assume the transistor is the current limit? i have seen a single transistor current limit before, and used them, very simple! be cheap too
     
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