MikeIcon
MikeIcon

Pooh-Bah
Location: Philadelphia, PA - USA
Member Since: 27th Mar 2003
Total posts: 2109
Posted:Ok, I did a little Yahoo searching but only found stuff in somewhat technical terms which I dont fully understand. The guys at Radio Shack were even less help. I know there are some people here who are very familiar with LEDs so would just be much easier to ask here.



Basically, I have a set of rollerskates that I want to attach LEDs to. I want between 2 and 4 LEDs on each skate depending on how bright they actually are. Guess Ill start with two at first and if I need it to be brighter, Ill add another two. Ive never done anything with electronics, circuits, or LEDs before so I basically need the simplest walkthrough on how to accomplish this. Ill be getting all my stuff from Radio Shack.



Which LEDs should I get (Im getting blue ones), they had a few different kinds with different mA values and such. I actually purchased a 3.7volt 20mA 2600mcd LED just to test stuff on which was the mid priced version of the 3 they had.



What kind of battery should I get? Im thinking 2 AAs?



What kind of switch should I get? I got a "Micromini Toggle Switch" which is a good size (smaller = better in this situation), but I really dont know if this has anything to do with the functionality of the set up.



Anything else? Resistors or anything? I put a 9v battery in the battery connector and touched the wires to the test LED just to see if it would light up and I guess the battery was way to strong for that LED cuz it started to melt lol. Yes, Im a TOTAL N00B at this smile Any help is appreciated.


Let's turn those old bridges we crossed into ashes.
We'll blaze a new trail,
and torch the rough patches.

-Me

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mtbeer
mtbeer

ARRRR!
Location: Charlotte, NC, USA
Member Since: 11th Aug 2004
Total posts: 529
Posted:Heh. Yup, you need those resistors.

If you use a 3.7 volt LED with a 9 volt battery you will need to drop the voltage by 5.3 volts. In this case a 270 ohm resistor will do that.

Use a resistor calculator for a quick answer. Resistor Calculator

Remember, you always need a resistor when working with LEDs. It might work without one if the voltage is balanced but chances are that you will fry the LED.

You can also drop the voltage by placing the LEDs in series. For example: two 3.7 volt LEDs in series hooked up to a 9 volt battery will act as a 7.4 (3.7+3.7) volt LED and need an 82 ohm resistor.

Adding batteries in series operates much the same way. example: two AA (1.5 volts) in series will produce 3 volts. (1.5+1.5).

It can get pretty complex if you want to have multi-color or blinking LEDs. For starters, stick with one color in an always on state.


"My skin is singed but it heals my heart and with glowing pride I'll wear my scars." -Davey Havok

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MikeIcon
MikeIcon

Pooh-Bah
Location: Philadelphia, PA - USA
Member Since: 27th Mar 2003
Total posts: 2109
Posted:So, does that mean that I can only have 2 3.7V LEDs hooked up to one 9v battery? And that 2 AA batteries wouldnt even be enough for one 3.7v LED? If so, how do beaming poi have 4 LEDs using 2 AAs?

Let's turn those old bridges we crossed into ashes.
We'll blaze a new trail,
and torch the rough patches.

-Me

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onewheeldave
Carpal \'Tunnel
Location: sheffield
Member Since: 28th Aug 2002
Total posts: 3252
Posted:I'd use 2 AA's rather than a 9v as you'll not need to use a resistor, and, if you accidently connect your LED the wrong way, AA's won't fry it like a 9V would.



2 or 3 LEDs (in parallel, not series) will happily run off two AA batterys; test it out by putting the AA batteries in a plastic battery holder and touching the LED legs to the terminals.



A while back I put up a webpage showing how I made really simple electric poi using AAs and LEDs without using solder, resisters and switches etc; it's here: -



http://www.geocities.com/combatunicycle/electrosock/electrosock.html
br>


I think this kind of approach could be ideal for you, if only as prototypes to see how they'll look with the skates; the link above takes you the second incarnation where I'd stopped using switches and took advantage of the ease with which one of the battery ends can be popped out of the holder to switch the circuit on and off.



There's also a link to the first design, which used switches.



All the components were purchased from Maplin. The LEDs were 'super bright' ones. The page includes Maplin product codes.


"You can't outrun Death forever.
But you can make the Bastard work for it."

--MAJOR KORGO KORGAR,
"Last of The Lancers"
AFC 32


Educate your self in the Hazards of Fire Breathing STAY SAFE!

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Stout
Stout

Pooh-Bah
Location: Canada
Member Since: 12th May 2004
Total posts: 1872
Posted:Have you considered using pre made LED "thingies" ? ( couldn't think of a better word) I went the route you're thinking of about six months ago in an attempt to make some LED poi and all I ended up with was a really fragile setup that lasted for all of,,,about six minutes. There's lot's of little LED pins and such out there on the market and they should be pretty easy to attach to your skates without having to worry about soldering, resistors, battery packs, switches. I managed to make a nice set of LED poi for about 8 bucks going this route.

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minimaniac
minimaniac

The Ladiees Man
Location: near swindon/ oxford
Member Since: 5th Nov 2004
Total posts: 360
Posted:using just two AA's you will be .7 volts under power and also having a larger powered 9volt battery the life and intencity should i think be much greater

I'm going to leave the army and run away to the circus

if not i will just become a MI5 agent !!!

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