help to build a led light sheet with 100 3mm leds

I Need help to build a led light sheet with 100 3mm LEDs they are 3.5v LEDs I have never worked with LEDs before or resistors so please keep it in simple terms. the idea is to use a 12v battery and reduce it to 3.5v supply any ideas comments are appreciated

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YARTZ (author) 9 years ago
Thanks forgesmith what do you think about the 12v battery do you think that it is over kill or should i be useing a 9v? if you have any other suggestions please feel free to share them.
Isn't your van 12V? I thought you'd be tapping it's battery for power. If you're uncomfortable hooking it up right to the battery or at the fusebox, if possible, there's always the handy cigarette lighter outlet, excuse me "power port" on newer vehicles (no lighter), for which you can either buy a male connector or salvage one off a cheap "emergency light" etc. The bought ones also have fused versions, you can size the fuse as needed, and fusing would be recommended in case of a short. The current draw would seem to be less than a lighter, or whatever size the outlet is currently protected at, so your smaller fuse should blow first. In the dim and distant past I have used such for a hot air blowing rear window defroster for which the connector eventually started melting, they're currently used for small 12V refrigerators, laptops, and 120V inverters, they can handle the draw of 100 LEDs.

And offhand I'd think you'd need more than one 9V battery, maybe several in parallel. Who needs the hassle?

Here's a commercial version of a 50 LED "trouble light." Also another and one more using 60 LEDs. They're 120V AC but the listings say the transformer is 12V, thus the question is if the transformer outputs AC or DC, which (I would think) would indicate if the diodes for the DC were in the plug-in part or the actual light. In either case, one could save the transformer for future use (cut it off with about 4-6" of lead left) and stick on a "power port" end for vehicle use.

Of course, that's not 100 LEDs, and you really want 100, right? ;-)
YARTZ (author)  forgesmith9 years ago
yep 100 think i will have a look at those links i will keep you posted on my progress. cheers :-)
=SMART=9 years ago
What is it for?
YARTZ (author)  =SMART=9 years ago
I am looking to attach it to the side of my van for putting my tools away this might be over kill but I would like to do it all the same.
Big Bwana YARTZ9 years ago
If your going to be using them outside, when your done soldering them and testing them to make sure they work, glue / seal them with an epoxy or silicone to stop moisture from damaging the wiring, leads, or entering into the LED and damaging the bulb... This way you will get many years of life from them....
=SMART= YARTZ9 years ago
i would use a torch, i cant help you much with the electronics sorry :(
forgesmith9 years ago
'Explain it to my neighbor' simple or 'explain it to the cat' simple?
;-)

Read this first. Then you have to know what the forward current rating is for those LEDs, so you can use the nice online LED Calculator which will draw you a circuit. Although if it was me, I'd find the resistor rating for 1 LED and get 100 resistors. Then it's a batch job, soldering one resistor lead to one LED lead (series connection) for all, then soldering one wire to all the remaining resistor leads and then another to the remaining LED leads (parallel circuit). Then I don't have to worry about any one of them going bad, rest will stay lit.
REDNEK7779 years ago
why?
YARTZ (author)  REDNEK7779 years ago
I like to tyr new things and it would be something no one else has LOL