hooking up some LED lights to a battery

curly haired boy

I snagged a nifty clear-bodied Nerf Maverick the other day:

and i thought it would be neat to take advantage of the transparency and make it light up. to that end, i stopped by radio shack and picked up 2 20-pc baggies of random LEDs and a single-cell AA battery holder.

i giddily started hooking things together, and found out:

1. a single AA battery doesn't make anything light up (due to the one-way nature of LEDs i did try them both ways)

2. TWO AA batteries in series burns out an LED. now i've got 2 dead ones and my room smells like a robot farted.

obviously these aren't the flashlight bulbs i used to work with.

the circuit i'm trying to make needs to use at least 6 LEDs. i've picked out 6 standard-size green ones that i want to use (they're identical). no idea on how much voltage each needs to properly light up, but logic dictates that it's somewhere between 1.5 and 3 volts.

due to space constraints within the maverick's rotating barrel, the maximum number of batteries i can fit in is probably 3 AAAs. i don't need the lights to stay on for any great duration, so a total battery life of a few hours (3-5 mebbe?) is fine.

to sum up: 6 identical green LEDs, maximum power supply voltage is 4.5v. google says something about resistors, but i don't know what i'd be looking for there. any tips on getting this to work would be great.

Ruckus

curly haired boy wrote: »

I snagged a nifty clear-bodied Nerf Maverick the other day:

and i thought it would be neat to take advantage of the transparency and make it light up. to that end, i stopped by radio shack and picked up 2 20-pc baggies of random LEDs and a single-cell AA battery holder.

i giddily started hooking things together, and found out:

1. a single AA battery doesn't make anything light up (due to the one-way nature of LEDs i did try them both ways)

2. TWO AA batteries in series burns out an LED. now i've got 2 dead ones and my room smells like a robot farted.

obviously these aren't the flashlight bulbs i used to work with.

the circuit i'm trying to make needs to use at least 6 LEDs. i've picked out 6 standard-size green ones that i want to use (they're identical). no idea on how much voltage each needs to properly light up, but logic dictates that it's somewhere between 1.5 and 3 volts.

due to space constraints within the maverick's rotating barrel, the maximum number of batteries i can fit in is probably 3 AAAs. i don't need the lights to stay on for any great duration, so a total battery life of a few hours (3-5 mebbe?) is fine.

to sum up: 6 identical green LEDs, maximum power supply voltage is 4.5v. google says something about resistors, but i don't know what i'd be looking for there. any tips on getting this to work would be great.

The packaging of the LED's should list the voltage and power consumption. We need those before we can design a proper circuit.

curly haired boy

unfortunately the baggie had none of those. HOWEVER, radioshack's website has this to say:

http://www.radioshack.com/product/index.jsp?productId=2062588

2 - 3 V, 10-20 mA leds (20)

Pel

I'm pretty sure Radio Shack LEDs are good to run off of 3 1.5v batteries. This is consistent with a 4.5v maximum voltage. The reason your LED burnt out was probably not because of the voltage but rather because, unlike ordinary bulbs, LEDs have a specific polarity (IIRC, the lead wires are usually shipped as different lengths, the longer one always being the same polarity, although my memory fails me as to whether that is + or -). Reversing the polarity will usually burn out the LED. Other than this, you should be able to wire them in a very similar fashion to an ordinary bulb. With a bit of tutelage from an online tutorial, you could probably wire a timer circuit to strobe your LEDs though, or add the appropriate resistors to fine-tune your power source to your LEDs exact power needs.

A 3 AAA power source would literally power 6 LEDs for days of continuous usage. Battery life will not be a problem for you.

matt has a problem

http://www.theledlight.com/ledcircuits.html

Here's a very handy guide for simple LED wiring. You're going to need to wire them in parallel, and you might need resistors to do that.

Ruckus

Probably 2.2V then, so you could do 2x LED's in series with 3x 1.5 batteries in series, or you could do 4x LED's in series with 6x 1.5v batteries or 4x LED's in series with 1x 9-Volt.

curly haired boy

thanks, i think i'll try some of those configurations.

would it be possible to have 3 sets of series-wired LED pairs, wired in parallel?

curly haired boy

good news!

on a whim, i tested 2xAA (3v) batteries with a single GREEN LED. before, my experiments had been only with red ones. apparently, green can withstand 3 volts, glowing healthily, while red cannot. this simplifies things quite a bit. i'll just hook up 6 of the green ones in parallel, and i THINK that should work.

many thanks to all for the help - i'll post pics if/when i get it installed/working.