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[Vraeden]

Does anyone know of a good, low-cost supplier for LED and LED-related stuff?

I'm looking at cannibalizing several Nerf blaster and I want to light them up from the inside.  Ideally, I'd like to us a 12v system, with an internally-mounted rechargeable battery, so I'd need a battery pack, charger, wiring, lights and a switch.

It seems that every place I search on the interwebs either sells LEDs for a car or house, or they're just the "finger" LEDs that are self-contained units and aren't connected centrally.

EDIT:  I should also mention that I've checked Radio Shack, and their prices seem to be a lot higher than anyone else. I guess that's the price you pay for convenience, right?

[wade vox]

Amazon has plenty of Led stuff but a lot of the Leds themselves come in bulk.

[Pointoforigin]

Ebay is pretty good actually, if you know where to look. Try here - I get my stuff from these guys.

http://stores.ebay.com.au/hkjeledlampcenter

I would say try and stay away from 12v - go for 2x lithium ions at 7.4v instead, or one at 3.7v depending on your needs. Li ions come in various sizes, Sanyo/Panasonic make the best cells. For the most battery life you'll want 18650's. That's 18mm by 65mm (give or take).

Check out www.thecustomsabershop.com/forum for lots of tutorials on setting up and using li-ions safely and reliably.

You should be able to make really simple and effective circuits that don't even need resistors if you pay attention to things.

[Vraeden]

What about a 9 volt setup?  Or will they burn out quickly?  I'm not planning on having any sound in my blaster (for now), so I just want it to light up.

My Ultrasabers use 3.7v AA batteries, 14500, I think.

[Pointoforigin]

Yup, 9v will be fine. I run 9v's in my gaunts for LED's. Most 5mm LEDs run at about 3v, so three in series is 9v, meaning no resistors are needed.

Note electronics gurus will berate me for saying that you don't need resistors. To appease them I shall now say, "Always use a resistor". But I like to cheat

And yes those 14500's would indeed be AA size li ions 14mm by 50mm. Or thereabouts.

[heavyd76]

check your local radioshack.  they may still have a lot of leds on clearance starting around 27 cents.

[Jerek Darr]

I use LED strips from my local auto parts store, they are designed to run on 12v, so a 9v will in them pretty much all day, actually the double strip on my jet pack got left on after a troop, and they were still glowing three weeks later, faint but on.

[Conner Adenn]

http://www.superbrightleds.com/ has a decent variety, but if you're looking for something cheaper, I'd say try out https://www.taydaelectronics.com/ their variety is kinda limited, but they are the cheapest I've found for most of what they offer

[Reneth Justalari]

Hmm, not trying to dust off the cobwebs, but this is definitely a great thread. Any chance a mod out there could maybe sticky it?

Also, I've personally been using http://the-led-shop-inc.myshopify.com/collections/5mm-led for my LEDS. They sell 100 LEDS for about $8.88 and all sets come with free resistors. I've always been pleased with the quality of the LEDS from this site as well. Hope this helps!

[Conner Adenn]

If you need basic red/green/blue/white LEDs, it would be cheaper from Tayda. $0.03 per LED, plus a penny for the resistors, so $4 per 100, plus a small shipping fee

[Vraeden]

Yes, I'm necroposting my own thread.

It's been a long time (more than 20 years) since I've calculated amps, volts and ohms in a circuit, so please for give the rambling.

So I finally went out and bought a bunch of LEDs and resistors off Amazon and wired a couple up in one of my gauntlets. 

I wired up one circuit with a 6 V power supply (4 AA batteries), 2 LEDs,  1 200 ohm resistor and an on/off toggle switch.  It seems to work well, but I'd like to put more LEDs in and not weigh down my other gauntlet with batteries.

So I was looking out on one of those circuit resistance calculators and saw something about wiring LEDs in parallel.  Some places say not to do it because it drains the power supply faster and if you do, always use the same color LEDs since different LEDs have different voltage drops.

At the same time, 5 LEDs wired in parallel can draw the same 3 volts.

Can you run LEDs at a lower voltage?  For instance, if my red LEDs are rated at 2 volts, but I hook them up to a single 1.5 V AA battery, what effect will that have on my circuit?  I won't need a resistor and they just won't be as bright?  Or should I hook them up to a 3V (2 AA batteries) power supply and then put a resistor on each of the LEDs? 

Should my resistors be before or after the LEDs in the circuit?

[Conner Adenn]

You'd still want to wire a resistor in for each LED, I usually attach them to the negative lines. Lower voltage would just leave the LEDs a bit dimmer, so you should be fine, but if you want multiple LEDs, I'd say go with a 3xAA battery box for 5 of them. a 2xAA box may work as well. If I had all my development stuff unpacked I'd offer to make a video of the differences, but half my shop is still packed up lol

[Reneth Justalari]

I've built circuits for folks in Firestorm that can power up to 15 LEDs (Blue and Red) on two 9v, with roughly 10-15 hour battery life depending on all sorts of factors with the batteries being used. I do "branch" circuits, two leads per "trunk" with multiple LEDs soldered together, and then place an appropriate resistor in there. It reduces wires especially when space inside a bucket is so precious lol Now, all that being said, there's a thousand ways to do the same thing. Conner's method is great for troubleshooting and to be honest, best practice for this. My approach is purely out of easy to fix, cheap to replace circuits.

Example of what I'm talking about that I did for Kalyn Solari's bucket.

[Guy'ikaab]

 

[Tarix Vizzan]

I've built circuits for folks in Firestorm that can power up to 15 LEDs (Blue and Red) on two 9v, with roughly 10-15 hour battery life depending on all sorts of factors with the batteries being used. I do "branch" circuits, two leads per "trunk" with multiple LEDs soldered together, and then place an appropriate resistor in there. It reduces wires especially when space inside a bucket is so precious lol Now, all that being said, there's a thousand ways to do the same thing. Conner's method is great for troubleshooting and to be honest, best practice for this. My approach is purely out of easy to fix, cheap to replace circuits.

Example of what I'm talking about that I did for Kalyn Solari's bucket.












I would be interested in something like this for my helmet!

[Pointoforigin]

Vraeden -

Voltage is how fast the flow is, amperage is how wide the pipe is. Does that make sense? So if you have 3 volts in a battery supplying 1 3v LED it will last for twice as long as the same battery supplying two 3v leds in paralell, and 3x as long as three 3v leds in paralell. With me so far?

So the way I did my gauntlets was the other way. With a 9v battery I put three LEDs in series, so one after the other - meaning that their voltage adds up. 3v + 3v + 3v = 9v - so no resistor required, and in series my battery will last longer. Like, accidentally left on in my bag for a week longer.

You SHOULD always use a resistor. But if your values are close, with that low voltage and amperage, there's no real need.

[Vraeden]

Does anyone know of a resistance calculator for different color LEDs?

I'm thinking of putting together a circuit powered by 4 3.7 volt Trustfire batteries, So I'd have 14.8 volts to work with.

My red and yellow LEDs draw 2 volts, and my purple, green and clear LEDs draw 3 volts each. If I wire them in series, I can't get to 14.8 volts, so I need to put a resistor(s) on the circuit somewhere.

Is that possible?  Or not advised?

[Fi-8015]

If you sum up the required voltages for all the LEDs you are having in series in your circuit and subtract the result from your supply voltage of 14,8 V and devide the result by the required current (usually 20mA=0,02A) you get the value of your resistor.
For example you want one of each kind you have in your circuit, so you have:

2V (yellow) + 2V (red) + 3V (purple) + 3V (green) + 3V (clear) = 13V

14,8V - 13V = 1,8V

1,8V / 0,02A = 90 Ohm

That should work fine.
I hope this was what you wanted to know.

[Vraeden]

If you sum up the required voltages for all the LEDs you are having in series in your circuit and subtract the result from your supply voltage of 14,8 V and devide the result by the required current (usually 20mA=0,02A) you get the value of your resistor.
For example you want one of each kind you have in your circuit, so you have:

2V (yellow) + 2V (red) + 3V (purple) + 3V (green) + 3V (clear) = 13V

14,8V - 13V = 1,8V

1,8V / 0,02A = 90 Ohm

That should work fine.
I hope this was what you wanted to know.

That's exactly what I wanted to know, thanks!

With a circuit wired in series, can the resistor go anywhere in the curcuit?

Also, if I use a resistor rated at a 200 ohms when I only need 90, what effect will that have?  Will it just make the LEDs a little dimmer?

[Fi-8015]

I am glad I could help, the resistor can be placed anywhere in the row. If you alter the resistor you can calculate the opposite way.

U=R*I

R is your resistor with a value of 200 Ohm
I is the current of the LEDs, presumably 20mA

U=200×0,02 V=4V

So you will lose 4 Volt over the resistor and will have 10,8V left for the LEDs. This will indeed result in a loss in light intensity.

[Vraeden]

So after taking the advice of everyone in this thread, I spent the last couple of nights burning my fingers with the soldering iron.

The end result is this:



There are three LEDs in the circuit.  It's driven by 4 AA batteries (6V) with 3 LEDs (2 red, 1 yellow) that draw 2V each.  I did not put a resistor in.  There is also a push-switch that turns the lights on and off.

The two red LEDs are in the barrels of the flamethrower/blaster and the yellow LED is on the inside of the gauntlet and is a visual indicator to me that the lights are on.  It seems I did something right since the LEDs didn't immediately blow up when I ran juice through the circuit.

Can you guess what in the picture is an indicator that I am old?

Now that I've wired up a couple of circuits, I'm just dangerous enough to short something out and make a battery explode while it's on my person.

Thanks to everyone for their help!