12w LED power supply modification from 220vac to 110vac

Sid12

n00b
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Apr 4, 2020
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1
Hi everyone! I recently bought about 20 led light online. Did not pay attention to the input power supply which is 220v ac. It doesn’t serve my purpose unless I modify it to 110v ac. I am attaching picture of the light. Can somebody tell me how I can modify it to 110v. Thanks.
 

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ryan_975

[H]F Junkie
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Feb 6, 2006
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Short of adding a step up transformer, there's not much you can do. The LEDs are wired in series so that they only "see" 3v-5v each when the whole circuit is powered by 230v. At 110v, there's not enough spare voltage to drive the LEDs safely.
 

N4CR

Supreme [H]ardness
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Oct 17, 2011
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I would just buy a step up trafo it won't need to be big for the LEDs just check draw first.. maybe 500w is enough depending on power.
Alternative is de solder them and buy a suitable constant current driver and drive them directly. Meanwell is good and cheap (can have expensive high end too) Taiwanese PSU.
 

Arcygenical

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Jun 10, 2005
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Just spend the 5$ for the 110v version of the same bulb.

That should be a constant current driver, throwing the sumVF of the diodes together to hit the Vacc (wall voltage). If you can separate the LED's into 2 banks, and run them in parallel off the same power transister... eh. A ton of work for more points of failure.

Hmm, 24 LED's so the math doesn't work out. Perhaps a voltage divider. Anything else on the other side of the board? I'm expecting at least a capacitor in that driver circuit.
 
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Mohonri

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Jul 29, 2005
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I've taken apart a fair number of LED light bulbs, and I'm an EE, so I can do at least a little bit of analysis.

tl;dr: Go ahead and plug it in to 110V. You won't do any harm to it.

Longer version: You've got 24 LEDs in series, which would come out to about 75-90V. That can be done with a 120V circuit just fine. The black box on the right in the photo is a rectifier (turns AC into DC), and the larger one on the left will be the LED driver. It's almost certainly a simple constant-current driver, which means that it'll operate off a fairly wide range of input voltages. If you supply it off 120V, the worst you'll see is a light bulb that doesn't light up. At best, you'll have a bulb that runs just as bright, but more efficiently and cooler, off 120V than 220V.
 
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