Intro: 120V LED Bulb on 12VDC, 190MA. the Hack
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:)
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:)
Step 3: Finger Power!
To test each group when you have the proper traces cut and soldered, use your finger. Hook your body in series with your test string and use a small screw driver or probe to apply power. You wont run the risk of frying your LED's if you made a mistake (trust me you will, i fried 2 legs on my first light before i got my technique right lol) They dont light up bright obviously, but you can see if there are any problems.
Step 4: Now Apply Power
There ya go, first string dont, pretty
Step 5: Now Finish Up the Soldering/wiring
now its time to wire up the rest. I chose to keep all the strings seperate to make them easy to dim. Just switch on 1 2 3 or 4 strings and you get dimming without need for a dimming circuit.
There ya go. A 12vdc 40W light bulb that only uses 190ma. The possibilities for this bulb are endless. Hope i at least gave you some ideas:)
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