LED Driver Matching.

Discussion in 'General Electronics Chat' started by Techmasteruk, May 3, 2017.

  1. Techmasteruk

    Thread Starter New Member

    Oct 13, 2016
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    hello all,

    I'm stuck with this LED projector yet again.

    I've the Sharp Mega Zenigata COB GW5DLE40MR5 rated @ 950ma min 1500ma max, 50v min 53.25 max. I ordered the driver pictured below rated @ 27~54V 1400ma constant current, however when I plugged the driver and measured the output on the DMM I got 56.2V 3270ma ! I hesitate to connect the LED chip in case I blow it up since the reading is not within the LED spec.
    IMG_0413.JPG
     
    Last edited: May 3, 2017
  2. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
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    How did you read the voltage and current that you quote?
    The voltage is within the spec (Max 61V) and the current is adjustable with an internal pot.
     
  3. Techmasteruk

    Thread Starter New Member

    Oct 13, 2016
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    0
    On the DMM I measured the VDC output, and current the same way. The driver is within spec, but for the LED it's 3V over the max.
     
    Last edited: May 3, 2017
  4. Techmasteruk

    Thread Starter New Member

    Oct 13, 2016
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    0
    Oops sorry it's 3.27ma not 3270ma.

    Can I use a resistor to reduce the DCV by 3V ?
     
    Last edited: May 3, 2017
  5. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
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    When you connect just a voltmeter to the output there is no output current so the supply cannot do its constant current thing hence it goes to a higher voltage. If you check the label you will see it says "max 61V" and that's the highest voltage it will go to and your voltage reading is within that so that's just what would be expected.

    When you connect just an ammeter to the output you are effectively short circuiting the output so the output voltage is pulled down to zero. The supply then protects itself by reducing the output current hence you get that low current reading. Again just as expected.

    On the basis of those two measurements the supply is doing just what it should do.

    Put on your safety glasses :))) and connect up the LED.
     
  6. Techmasteruk

    Thread Starter New Member

    Oct 13, 2016
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    Well explained AlbertHall, I will give it a try & hopefully nothing will explode :). Many thanks.
     
  7. Reloadron

    Distinguished Member

    Jan 15, 2015
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    This cartoon may help. When measuring current the current meter goes in series with the load and when measuring voltage the meter goes across the load or simply put across the power supply output.

    Meters.gif

    Ron
     
  8. Techmasteruk

    Thread Starter New Member

    Oct 13, 2016
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    Thanks Ron, I guess if i draw 1400ma the voltage will drop to about roughly 51.6 v if I'm correct ?
     
  9. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
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    Yes.
     
  10. Techmasteruk

    Thread Starter New Member

    Oct 13, 2016
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    Super, sometime I surprise myself :D
     
    Last edited: May 5, 2017
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