Instructables

120V LED bulb on 12VDC, 190MA. The hack

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I wanted a 12 volt lightbulb For my home RE system that looked and functioned like a normal light, brightness etc. But one that didnt use a lot of power. I found these at LOWES for under $10 and decided it was time to hack:)
 
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Step 1: The guts of the typical LED lightbulb

Well here it is, bunches of LED's.  First thing you probably want to do is measure where the power is being delivered to the board. In my case it was 30VDC.  BE CAREFUL not to look at the lights when lit.  Also take a voltage reading across ONE LED while its powered on. 

Step 2: Preparing the LED board for conversion:)

This bulb ran on 30 volts, so with a little math: 30 divided by 3.25v (single led) you get 9 ish. since we have 18 led's in this light, it means theres 2 strings of series wired groups.  This can help in isolating the proper LED's for groups of 4 each.  Since one series of 9 LED's is already wired together, you can divide it in half. Running on 12vdc, each single LED will be at 3volts.  Run your groups of 4 led's in parallel to eachother (in this case that gives us 4 groups) What to do with the remaining 2 led's? Isolate them and either wire in resistance to run 2 led's on 12vdc and wire them parallel to the other groups, or do what i did and wire it seperate for a night light:)  Also since the math tells me that there are already 2 strings on this board, there is a common point between them.  Look for that and build from there.  Trust me, find this first, it makes figuring trace cuts etc MUCH easier lol  Start at V +

Next is the pain in the azz part. Carefully cutting the right traces and soldering everything up:)  Ill assume you have these skills already so i wont bore you with the details of that task. Plenty of instructables here to teach you if you dont:)
azmanyaacob13 months ago

I'm in the making of 12Vdc lighting system at home - friendly reminder if battery is a power source (in my case - I use seal lead acid) , please consider to put a low voltage disconnect circuit between 12vdc source & load. Frequent discharge down below 10V will eventually damage the battery.

good job on the instuctable, I don't mean to be picky but, if the light consumes 190ma @ 12volts then it would be a 2.28 watt light bulb, as watts is a measure of the power consumption not light output.
Thats not a bad thing, I think you mean it has the same light output as a 40watt incandescent light bulb.
HawaiianGuy (author)  liquidhandwash1 year ago
You are correct:) Thats the beauty of LED vs. incandescent bulbs. Its light output is like that of a 40w bulb, but consumes only 2.3ish watts. And i can attest to the brightness, next to a regular 40w bulb, its pretty close. Its light output seems a little "whiter" but its plenty bright.