Is this driver any good?

DIWdiver

DIWdiver

Flashlight Enthusiast
Joined
Jan 27, 2010
Messages
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Location
Connecticut, USA
That should work. Can't say it's good, as I don't know anyone who's used them.
 
M

mnm99

Newly Enlightened
Joined
Nov 29, 2014
Messages
76
That should work. Can't say it's good, as I don't know anyone who's used them.

I found this one. Looks solid. This is what I'm trying to do. I will be connecting 2 arrays to the power supply. Question..Do I really need the resistor?? And shouldn't it be on the + side too?

http://www.ebay.com/itm/271212911929?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

3 x 8 array uses 24 LEDs exactly

+12V
wizc-ul.png
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R = 1 ohms
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R = 1 ohms
wizc-le.png
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wizc-r.png
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R = 1 ohms
wizc-lterm2.png
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R = 1 ohms
wizc-d.png
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wizc-d.png
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R = 1 ohms
wizc-le.png
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wizc-d.png
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wizc-r.png
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R = 1 ohms
wizc-le.png
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R = 1 ohms
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R = 1 ohms

The wizard says: In solution 0:
  • each 1 ohm resistor dissipates 490 mW
  • the wizard thinks 1W resistors are needed for your application
  • together, all resistors dissipate 3920 mW
  • together, the diodes dissipate 67200 mW
  • total power dissipated by the array is 71120 mW
  • the array draws current of 5600 mA from the source.
 
Last edited:
DIWdiver

DIWdiver

Flashlight Enthusiast
Joined
Jan 27, 2010
Messages
2,717
Location
Connecticut, USA
Your numbers don't add up. 12V input times 5600 mA is 67200mW. That's all the power there is available. That's the sum of the resistors and the diodes. So instead of 71120mW, the array number should be 67200. The Diodes are 67200-3920 = 63280.

But if you have 12V and 1 ohm, and 700 mA, then the LED string voltage must be 11.3V, making the individual LED voltage 3.77V, which I'm pretty sure isn't right. More likely, the LED voltage is 3.6V, so the string voltage is 10.8V, leaving 1.2V across your resistor, giving you 1.2A and 1.44W.

Oh, and yes, you absolutely need the resistor. You can only get rid of it if you use a constant current regulator instead of a constant voltage regulator. That's why LED drivers are constant current drivers, not constant voltage.
 
M

mnm99

Newly Enlightened
Joined
Nov 29, 2014
Messages
76
Thanks I went with a flexblock after your reading. Can you comment on my other thread? Thank You
 

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