# LED wiring to AA batteries



## madmomma (Jul 1, 2009)

This may be a dumb question for all teckies but... I have 2 red LED assemblies (w/resistors) that I want to hook up to 4-AA battery holder (or 4 AAA) with on/off switch. Each LED forward voltage is 12.0V, Forward current 12mA. Would 4 AA's or 4 AAA's be enough power for these "eyes" because the LEDS have built in resistors? Help, please, I'm not an electrical wiz and my first attempt didn't come out ok. Should I be using a 12V source?


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## Otaku (Dec 3, 2004)

Take another look at the 12VDC spec for those eyes. I doubt that the LEDs themselves have a forward voltage of 12 volts, especially not at 12mA. The built-in resistors may be such that a 12VDC supply is needed to light the LEDs, though. A 4AA (or 4AAA) battery pack will put out 6VDC, probably not enough to light the LEDs. The easy way to do this would be to hit the local thrift store for a 12VDC wart, 100mA or more, and attach that to the LEDs. The alternative would be to remove the built-in resistors and attach one that will work with 6 volts. Remember that LEDs are polarity-sensitive. You won't kill them if you get the polarity wrong, but they won't light. If they don't light on the first try, just reverse the connection.


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## asterix0 (Nov 5, 2008)

Why not try 8 batteries (2 four packs in series)?


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## hpropman (Jul 27, 2008)

sound like your are trying to hack something did these red led assemblies come out of a prop or were they something that was made? what do you want to do with them?


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## madmomma (Jul 1, 2009)

Here are pix of two different leds, one with built in resistor and the other without. I'm trying to put a pair of either in a large foam skull the easiest way possible with batteries. I have battery packs with on/off switches and hold 4 AA's and 4 AAA's. I can't believe this could be so difficult. LEDS are EVERYWHERE and don't have bulky transformers connected to them, only batteries. Am I missing something???


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## Otaku (Dec 3, 2004)

Can you post the Radio Shack part numbers? Once I have the p/n's I can recommend a resistor/power source.


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## madmomma (Jul 1, 2009)

The Jumbo Super Bright (5000mcd intensity) Red LED is part#276-086
The Red LED Assy w/built-in resistor (only 110mcd intensity) is Part#276-0270 
Obviously I would be using two of either.


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## madmomma (Jul 1, 2009)

Also the super bright says its rated 2.4V, 20mA, 10mm with forward voltage 40mA max. I don't know if that helps any. I thought the red LED assy would be easier to hook up because it has the resistor built in already and is wired to go.


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## Otaku (Dec 3, 2004)

The LED calculator sez:
For two of the 10mm LEDs in series (eyes) use a 56 ohm, 1/4W resistor with the 4AA (or 4AAA) battery pack. If the 56 ohm is hard to find at R-S, you could use a 100 ohm with no appreciable reduction in brightness.
The ones with the built-in resistors need a 12VDC power source, like a low amperage wall wart, 12VDC @ 100mA or more would it. If you really need portability, you could also wire two 4AA battery packs in series with the LEDs (as suggested above) to get the required 12 volts.
The wiring would look like this:
Red wire from LED to positive of battery pack "A", negative of battery pack "A" to positive of battery pack "B", negative of battery pack "B" to black wire of LED. If wiring two of these LEDs in series, like for eyes, connect the red wire of one LED to the black wire of the other, then connect the battery packs as described above. Make sure the switches on the battery packs are both "on". Hope this helps.


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## hpropman (Jul 27, 2008)

If you can solder then just solder the resistor to one leg of the led and then the wires from the battery pack go to the other end of the resistor (the one not soldered to the led) and the the other leg of the led. If you need a picture let me know and I will sketch something up. Note: before you solder the wires touch them to the leads to make sure that the led lights first if it does not reverse the wires. Once you are sure which goes where then you can solder the wires from the battery pack.


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## DeathTouch (Sep 6, 2005)

Would be better if you knocked that down to 4.5vdc. If you have a Menards, they have 4.5vdc power adapters. I use that for my flying crack ghost LEDS.


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## hpropman (Jul 27, 2008)

I think she wants to keep this battery powered otherwise I would use a wall wart too.


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## DeathTouch (Sep 6, 2005)

Then she should keep it 3 batteries.


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## Otaku (Dec 3, 2004)

DeathTouch said:


> Then she should keep it 3 batteries.


Good advice, but I think she's already got the battery holders.


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## madmomma (Jul 1, 2009)

You've all been so helpful. Here's what I'm going to do...since I have the battery packs already, I'll use 2 of them wired together as suggested with the one set of LED's and get a wall wart for the others. I've never used a wall wart so this is a good time to start. I can position the skull where you don't see any wires and just get the bright creepy effect. I'll try to post the pictures afterward if they don't come out too dark. Again, you guys are awesome...very helpful. Wish I could return the favor sometime! Happy Haunting!


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