Introduction: LED Beginner Project: Part 2

Picture of LED Beginner Project: Part 2

This project was my next step in my exploration of the world of LEDs. Here, I will show how to wire LEDs in parallel in order to make a simple bike light. Wiring LEDs in parallel is useful in that you can run multiple LEDs off of a single, low-voltage source.

Step 1: Materials and Such.

Picture of Materials and Such.

I've always been looking for a reason to use an Altoids tin as a project box, and this project seemed to be it.

- Altoids tin
- 2 AAA battery holder from Radioshack.
- three way toggle switch that I scavenged. I used a three-way switch becuase I plan on eventually adding a circuit that will make the light have a blinking mode. If you don't care to add this extra complexity to the light, just buy a simple SPST on-off switch.
- three white, 3V LEDs given to me by a friend.

In my previous Instructable, I explained how LEDs need to have resistors wired in series with them to keep them from blowing out. In this case, I didn't need resistors, because the supply voltage was exactly 3V and the requirement was 3V. If you are using LEDs with a lower voltage requirement, you will need to add in a resistor to keep them from burning up.

Step 2: Why Parallel Is Awesome.

Wiring LEDs in parallel opens up new ways of using them. In my last instructable, we saw that LEDs wired in series have their voltage requirement add up. This is acceptable if we are using a small amount of LEDs, becuase it ensures that each LED is at its maximum brightness, but as we start adding more lights on, we find a need for higher and higher voltages...imagine if you wanted to run twenty 3V LEDs in would need to have 40 AA batteries to power it!! Wiring in parallel means that the voltages do not add up...the same voltage goes to all the LEDs. This means that we could run those same twenty 3V LEDs off of two AA batteries instead of 40. The trade off is that those two batteries will be drained much faster, and the LEDs will not be at their maximum brightness. But, for all practical reasons, if you want to have a portable multi-LED light, you're going to have to wire them in parallel.

Step 3: Preparing the Altoids Tin.

Picture of Preparing the Altoids Tin.

Plan out how you want the LED arranged. I chose a simple straight line in order to make it clearer how they are wired together, but you can do it whatever way you want to!

Step 4: Clip the LEDs

Picture of Clip the LEDs

Next, we clip the legs of the LEDs shorter so that they dont stick out all over the place inside the tin. When you clip them, make the positive leg longer than the negative leg. If you dont know how to tell which LED leg is positive and which is negative, check out my last instrucable.

Step 5: Glue LEDs and Battery Pack Into Place.

Picture of Glue LEDs and Battery Pack Into Place.

Glue or otherwise affix the LEDs and battery inside the case. When arranging the LEDs, be sure to have all the positive legs facing one way, and the negative legs facing the other.

Step 6: Mount the Switch

Picture of Mount the Switch

drill a hole for the switch, and mount it wherever is most convenient for you

Step 7: Start the Wiring.

Picture of Start the Wiring.

Wire the positive lead from the battery holder to one of the contacts on the switch. Now, wire the negative lead from the battery pack to the negative lead of one of the LEDs. Then, wire all of the NEGATIVE leads together. This is the difference between parallel and series. In series, the positive leg of one LED is wired to the negative lead of the next. In parallel, all the negative leads are connected to each other, and all the positive leads are connected to each other.

Step 8: Finish Up the Wiring.

Picture of Finish Up the Wiring.

wire all of the positive leads to each other, and then wire them to one of the contacts on the switch (for this particular switch, it is important that the contacts that you solder wires too are adjacent to each other.)

Step 9: Enjoy the Working Light!

Picture of Enjoy the Working Light!

The next step is to mount it on your bike somehow. Different people do this different ways, and I'll leave it up to your inventive mind to concont something!


tipigeon (author)2016-11-27

You didn't need resistances?

ekgeml. (author)2015-02-08

Will either of these on/off switches work?

Toggle switch single pole throw on off 125vac @5 amp


a push button switch momentary 1 amp 250vac

I'm looking for some VERY inexpensive ones and these are about a buck each at Jameco. If they won't, what amps/vac should I be looking for? Thanks!

svannieuwenhuyse (author)ekgeml.2015-08-21

The first one will, the second one powers off once you let it lose. If you would like to use the last one you'd need a flipflop.

fastfilmsinc (author)2010-05-27

if you had a 6V power source and 6-1V  would you need resistors is you did it in the parallel way?

I think I understand what you mean. You have 6 LEDs that require 1V each and you have a 6V power supply. This is perfect for wiring in series. I did this with a 9V battery and 3 3V LEDs in my Bike Light instructable.

Charthage (author)2009-01-31

You might want to add some rubber inserts on it so you don't short out your LEDs.

hikarudigi (author)Charthage2010-12-15

Good point and very true about adding the rubber. I did a thin strip of black electrical tape around the inside lining of the tin.

Salsa766 (author)2010-06-18

Incredible tutorials, I can't figure out how to make a flashing LED circuit b/c all the other instuctions aren't as thorough as yours. So if you could make an instructable on how to make those LEDs flash, that would be awesome. :)

lifesavin (author)2009-08-04

I am totally new to all this stuff. Could you add say a 4 AA battery box and add more LED's and use this as a flash light or as a lantern for camping or such?

rungdc (author)lifesavin2009-11-21


fastfilmsinc (author)rungdc2010-05-27

you could probably do it if you did the leds in the parallel way...

jonsbuks (author)2010-02-08
Excellent hands-on follow up to your first tutorial. My Bunker Hill wireless alert signals an intruder by issuing a doorbell three LEDs blinking together. I plan to cut the speaker wires to make the unit function in a silent mode with only the LEDs activated, but presently the LEDs blink once, when the intruder breaks the transmitter’s beam. Is there a way to keep the LEDs lit until I hit a reset switch?  
legendofmatt (author)2010-01-03

Thanks for the Instructable. I used a 100 ohm resistor, a 9V battery, and a Momentary push button switch. a little different but I like yours better. here are some photos :D

amadoraa123 (author)2009-02-28

Wonderful Instructable. Thanks! This really showed me how to work with LEDs. But I used a 2.4 volt LEDs with a 150-ohm resistor along with a 9V battery. I also didn't clip the LED. .

abbtech (author)2009-01-21

Nice job! As Jeasterlingtech mentioned I would suggest using some current limiting resistors. The Altoids tin seems to be so popular for these cool small enclosures and looks great in this project. :)

If you are looking for some LEDs with some cheap shipping rates (starts at $3.00) please have a look at our store

If you are wanting to run an LED from a single AA battery here is an idea.

youarealwaysfree (author)2007-04-09

Thanks for the instructable - this was my first electronic thing out of components. I went for the "cadillac" version and bought a small prototype case. It turned out more of a flashlight than bikelight:

Willd (author)youarealwaysfree2007-04-10

Dude, that looks awesome. I need to find a place to get cheap switches like that, theres not end to how useful they are!

raykholo (author)Willd2008-11-26

buy in bulk online for cheaper prices

youarealwaysfree (author)Willd2007-04-10

Thanks! That one is a Philmore on/on switch (only wired half of it) i picked up at Fry's for about a buck . Seems kinda expensive, though? i bet you could find it cheaper elsewhere/online.

RadioShack has a good selection of switches, most are relatively cheap as well.

Darkshot (author)Firebert0102007-11-17


Firebert010 (author)Darkshot2007-11-17

No, the ones at my store average at around $1-$2, are you thinking of other components?

Darkshot (author)Firebert0102007-11-17

no...look online at radioshack type in SPDT flip switches and you will see

Firebert010 (author)Darkshot2007-11-18

Online prices tend to be more expensive.

Darkshot (author)Firebert0102007-11-18

not if it says "our exclusive" which means they always have it in the store at that price

Firebert010 (author)Darkshot2007-11-19

Look dude, they're no more than $2 at my local Radioshack, please stop arguing with me. I know that, I buy them often. I promise I'm not trying to mislead you or anyone else here. If they're different where you live so be it, prices vary.

Darkshot (author)Firebert0102007-11-24

arguing is what comments are for! and i will check that out the next time i go there i usually look um up online at radioshack and then buy them in the yeah....i will check that out my friend

Derin (author)Darkshot2008-03-18

I FOUND FOR 50 YKr OR LESS ps.YKr is our currency which is like the us cent.According to today's equal rates that should make 63 cents

Darkshot (author)Derin2008-03-18

O.o we were kinda done with the argument a while ago...

TrickedOutPc (author)2008-07-28

I am new to leds can the legs of the leds be touching the tin or would it short it out. I noticed now it looks like your ends are sticking up off the tin. I am using 3.5v leds and a 2.5 would I need a resistor and if so which one. I am doing 2 3.5v and 2 2.5v leds. thanks for your help.

rmcnaugh (author)2008-07-07

great tutorial. I made mine from a small car tin, so the battery holder is on the outside. I also used one red led and 2 ultraviolets. It's my 2nd led project. one thing, no matter how i wire the leads to the switch, the center led (this case the red one) blinks in1.5-2sec intervals as if there is a timer chip, in the switch. Is this the case? I like it, but I want to be able to control the blinking function. overall I'm kind of happy with it. In the dark, it reminds me of the "spinner" from blade runner. also I made another led project with altoids box with a green, high powered red and RIF led. do you have any tutorials for RIF leds. rmcnaugh

Rae-senpai (author)2008-06-03

Thank you for posting this! I've been looking for a simple LED project to start with, and I chose this! I also had to mess with the switch a bit before I figured it out, but otherwise your instructions were clear. Thanks again :)

tonton101 (author)2007-12-12

A very comprehensive tutorial for beginners! That's a plus! Anyways, How long will it stay on? a week?

Derin (author)tonton1012008-03-18

100000 hours total if battery drain ignored but i dont know with drain in calculation

lacrosse2man (author)2008-01-27

where do u get leds

Shifrin (author)2008-01-02

Hey, Nice Instructable! I'm planning on making one, I'll post up the results!

MaxL (author)2006-09-02

I went to Radioshack and I couldn't find any LEDs with a voltage of 1.0. In fact, I couldn't find any with less than 1.7. Where do I get LEDs with such a low voltage requirement? Is there a place I can get detailed information about LEDs?

kadris3 (author)MaxL2007-11-06

a couple of types will serve you well. white, green, blue and UV require 3.4 vdc for the published brightness. red,orange,yellow, and amber have a forward voltage of 1.2 vdc. most circuits require a current limiting resistor to keep them out of thermal runaway. 4.5vdc (3 aa cells) and a 47 ohm resistor should be about right for one w,b,g,or UV LED. 470 works fr 12vdc. 3vdc and a R,O,Y,A led will work also w 47 ohms and one led. 680 for 12 vdc. a string of 3 white and a 100 ohm resistor will work on 12vdc. you get the idea.

kadris3 (author)kadris32007-11-06

major mistake R,O,Y,A have 2.1 forward voltage . pleasee correct above. sorry

Sketch (author)MaxL2006-09-30

Hey MaxL you actually need 3V LEDs as the materials says. These LEDs are in parallel so each has to have a 3V voltage drop over it to consume the 3V's being supplied by the AAA batteries.

azebra5 (author)2007-10-16

I've never really built anything on my own, just put together some kits with kids. I'm ready to go back to one of the kits which won't work and who knows maybe I'll be lucky and find the fault in it. LEDs fascinate me and hubby has shown me how they can be put together to make lights. A SAD light is required yesterday. It got me started with LEDs and your instructables are feeding my continuing need to know. Thank you so much.

Darkshot (author)2007-10-01

thanks for the awsome project to do i made one!!! looks cool also thanks for the switch trick i didnt know how to wire switches before so this really helps because im building the beetlebot instructable and i luv to mod it hella times over enyway thanks :D

Sync (author)2007-08-14

hey, this will be my frist electronic progect EVER. im wondering if home depot is a good place to get all this stuff

DayDreamin69 (author)2007-07-21

I plan on making this later, but I was just wondering, if you were going to add a resistor, where would you put it? ( Haven't done any of this stuff before.)

lawizeg (author)DayDreamin692007-08-01

ill make this in my own way, thanks for the basic idea though.

Soo (author)2007-03-10

That's cool. Its goog to see LED projects like that

hockeyteeth (author)2007-02-22

Awesome instructable!!! I just completed my light an hour ago. Thanks for the resources to make my first electronics project possible.

tonsofhoopla (author)2007-01-16

Like it, but... I had to look to see how you wired the switch. But Nice Job aside.

Jumpin (author)2007-01-01

I did it, I did it! This was my FIRST electronics project... I build computers (or assemble them), but nothing has been THIS satisfying. I have wanted to do this for a long time. If I could add some suggestions: 1. Push the LED through the hole of the Altoid tin, don't feed the electrodes into the hold, the LED has a bevel that holds it in place... I backed them in... I wound up cutting them out. 2. I mixed my blinking LEDs (5V) with a LED (3V) and it never did work right until I took that 3V one out. Is this because the correct voltage didn't go through the rest of my LEDs? You feedback is most welcome. 3. You could presolder so that you can drop into a deeper tin (I have a LOT of International Coffees tins I've been collecting)... this would accommodate a larger battery pack like a 4AA pack, to power those 5V LEDs better. I'm so stoked that this site exists:)

carlosdreyfus (author)Jumpin2007-01-02

try using resistors to limit the current, use the voltages that u know, 3V and 5V and calculate the resistor that u need so the 3V resistor wont suffer at voltages higher than 3 volts. <a href=""></a> great source to figure out the resistors.

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Bio: Lets make something
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