VARIABLE VOLTAGE LAB POWER SUPPLY USING PSU

  1. Kiwi

    Kiwi

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    Kiwi submitted a new Showcase Item:

    VARIABLE VOLTAGE LAB POWER SUPPLY USING PSU

    Read more about this showcase item here...
     
    Kiwi, Nov 30, 2014
    #1
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  2. Kiwi

    rich-38

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    You use this for your startmotor, ive seen a lot, since my father had a lease/repair company, but smps can'tstand the powerdraw. Just google and you'll see that they just use supercaps, which can withstand the currentdraw .... You need a big buffer
    which can deliver that current. Psu's from computer suck, that's chinese rubbish and certainly not made to the purpose you want it for. 20A for a longer time Isn't a problem for thyristors or fets, not constantly, your pcu has also 10 powerfets switching fast, just like a grapic card, but whatever you use supercaps are the safest. Watch an poweramp class d. and the row fets and capacitors to deliver the powerdraw
     
    rich-38, Mar 29, 2015
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  3. Kiwi

    davenn Moderator

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    I don't think he is really worried about the starter motor, rich-38

    for starter motor turning on the avg 12V powered car, you require a minimum of 600 -700 amps
    peak current draws often hit 1000 amps for brief moments

    Dave
     
    davenn, Mar 29, 2015
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  4. Kiwi

    Kiwi

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    What I was referring to when I mentioned "cranking" was the effect that the low voltage during engine starting would have on the equipment I was working on.

    Electronic circuits designed for automotive applications need to have a fairly wide voltage supply range.
    The vehicle may have a nominal voltage of 12volts, but the circuit must be able to operate between about 9 - 15volts without failing.
    You would get pretty annoyed if your car stereo lost all its radio station pre-sets every time the engine was started, just because the voltage dropped to 10volts.
     
    Kiwi, Apr 11, 2015
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  5. Kiwi

    Maddhung73

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    Cool project man, keep that imagination a CRANKIN!!! (no pun intended)
     
    Maddhung73, Sep 5, 2015
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  6. Kiwi

    peterlonz

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    To be honest I can't see how you intend using your DIY device.
    This does not help anyone wishing to suggest improvements.
    One thing I'd suggest is you allow for case ventilation if you intend operation for more than 10 mins or so at a time.
     
    peterlonz, Jan 4, 2017
    #6
  7. Kiwi

    Kiwi

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    Hi Peter,
    Sorry I haven't replied earlier to your semi-negative comments regarding my project.

    It has been getting quite a bit of use at home and at work. Beats hunting around for the correct voltage wall wart to run something.

    As I said at the start, the unit was made to help me with the automotive equipment I work on. This is probably a different situation to most of the people on this forum, so may not be totally suitable for everyone's usage. Being able to simulate the voltages present during vehicle cranking and charging has been a great help.
    Anyone got any suggestions for improvements?

    Overheating has not been an issue, even when used for extended periods. If you look closely at photo #5 you will see eight holes through the bottom of the case. The fan in the power supply sucks air up through these holes, past the heat sinks on the voltage booster and then out the back.
     
    Kiwi, Sep 1, 2017
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  8. Kiwi

    Irv

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    Very neat job! I like the "glass top" case :)
     
    Irv, Sep 2, 2017
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