Need help building a 4vdc 13a power supply

Discussion in 'The Projects Forum' started by mrriso, Mar 16, 2011.

  1. mrriso

    Thread Starter New Member

    Mar 16, 2011
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    I am wanting to build a 120vac to 4vdc 13 amp power supply to drive a Luminus Phlatlight CST-90 led. I am using it in my Mitsubishi HC1500 dlp projector to replace the UHP lamp. I am currently using a 5vdc 5amp power supply that drops to 4.41vdc 8.5amps when connected directly to the led. It needs to be able to fit in an area 100mmx50mmx35mm. This led can handle 13.5 amps @ 3.9vdc to produce 3300 lumens. Can you guys help me build this?
     
    Last edited: Mar 16, 2011
  2. wayneh

    Expert

    Sep 9, 2010
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    I'd spend more time shopping for the right supply off-the-shelf, because your requirements are challenging for a DIY project. With that much power and so little room, you'll want to use a SMPS unless you could tolerate a transformer outside of the enclosure.

    On the upside, lighting an LED is easier than other applications and can tolerate more noise. Is it possible your LED could tolerate pulses to, say 12v or even 20v, if it is not continuously lit? Sending a PWM signal of 20v at low duty cycle would give you more efficiency and might allow you to use something like a laptop charger.
     
  3. mrriso

    Thread Starter New Member

    Mar 16, 2011
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    This is the power supply I am using now.Do you think this is PWM? Do you think I could use 2 of these in parallel?
     
    Last edited: Mar 16, 2011
  4. wayneh

    Expert

    Sep 9, 2010
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    That's a SMPS (switch mode power supply). You might be able to use more than one of them but I wouldn't just put them in parallel like you would a battery. Maybe someone here can advise.
     
  5. mrriso

    Thread Starter New Member

    Mar 16, 2011
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    This is how I want to wire it up.
     
  6. FADM Stern GNSF

    New Member

    Mar 17, 2011
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    I have used SMPS'a a lot in the past, and while some types may be capable of joining in parrallel as you have shown, I would never do it without using blocking diodes. I have ganged up these types of supplies using a diode (rectifier) in the positive lead of EACH SMPS. The diode would have to be capable of passing the required current, and in your case would use something that could handle 10 AMPS. These used to be very hard to find (and in a bolt style pack) but they are now very common (for solar cell and wind turbine projects)

    Hope this helps
     
  7. mrriso

    Thread Starter New Member

    Mar 16, 2011
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    That is a good idea. I will see if I can find some.
     
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