How to make a LED Flashlight bulb - for 2, 1.5 volt batteries (3 volts total) Photo Gallery by dloftus at pbase.com

How to make a LED Flashlight bulb - for 2, 1.5 volt batteries (3 volts total)

NOTE: If you find this series of photos helpful, please vote for this gallery. Since I created it in October of 2003 it has had 45,000 (as of July 07') hits and recently it gets about 1000 to 1200 hits per month. It would be nice to see it in the "popular galleries" section of pbase

Here is how to make a regular flashlight bult into a LED light bulb. It is easy, but you will need some tools, like a soldering iron, pliers, rosin core solder, etc. I'll cover the different parts needed at each step. Jusk click on the photos and you will go to each individual image and each has a caption. The best way to do this is click on the first photo and then just click "next" to take you to the following photo. Works great, kinda like a slide show!

Tape and bulb	Break glass with pliers	Inside of bulb	Desolder end of bulb
Parts needed	Cut ends short	Tin the LED lead	Tin resistor
Join resistor LED	Heat shrink	Solder spot on case	Solder side leg
Bend wire at end	Solder end cap	Finished bulb	Bulb on - MS
Bulb on - CU

post a comment

dloftus		10-Sep-2007 13:47
Guest, if you have an LED that only requires 1.5 volts then I don't think you need the resister. The LED show below runs at about 2 volts, so you need two batteries to provide a high enough voltage and the resister to lower the 3 volts back down to 2 volts to you don't over power the LED. Check your specifications to make sure they are not talking about "back voltage" which I think has to do with reversing the battery connections before you blow out the LED. Hope this helps.

Guest		08-Sep-2007 19:35
Something I'm confused on. If you have a 1.5 Volt battery and a LED that run 1.5-1.6 Volts. Do you still need a resistor?

dloftus		27-Jul-2006 20:09
I was going over the previous posts and found out the information page on the LED at the web site for Radio Shack has changed. For specifications of the LED go here: http://www.radioshack.com/product/index.jsp?parentPage=search&pg=2&cp=&productId=2062563&origkw=LED&kw=led&kwCatId=2032058&tab=techSpecs Hope this helps everyone.

dloftus		27-Jul-2006 18:23
Joe, glad to here it worked out. It's always a bit exciting to experiment with a project and have it meet expectations. Good work.

Smokey.Joe		17-Jul-2006 02:50
Awesome! I have been searching on a way to take a small flash light, with 2 triple A batteries and convert it to have a UV LED. I tend to GeoCache a lot and a small percentage of the Cache's require a UV light to read the instructions to the find the cache. With this tutorial, I should have my UV Flash light up and running. Oh the reason I chose to use a UV LED instead of going out and buying one, I have a UV LED laying around the house. Once I get the correct size resistor, I should be good to go. I had to modify your details a bit. The LED I have is a 3.3-3.6 forward voltage. therefore I had to replace the batteries with 3 small button batteries (4.5 volts). THe 2 triple A batteries just dont' supply enough "juice" to the LED. Hopefully with your help here, I should get it going tomorrow.

dloftus		25-Apr-2006 15:50
Joe, The LED bulbs I make are either red or amber because I'm using them at night for astronomy purposes. I haven't tried the white LEDs, but the use of an amber filter sounds like the best solution. I know the light is a blue/white, but what purpose are you using them for that would make the light color a problem?

Joe		24-Apr-2006 14:31
Great site! How do you get the blue out, when using bright white leds? I have used an amber lens and that helps. But some blue gets thru.

dloftus		27-Jul-2005 12:59
Here are a few sources I found on the web for making LED bulbs so you can get some other ideas. Hope this helps. How to make a white LED bulb: http://www.alpharubicon.com/altenergy/whiteledspitfire.htm Another “Make a LED light bulb” web page: http://www.alpharubicon.com/elect/ledlightbulb.html Building a LED flashlight and this one has the formula for figuring out the resistance needed so you can use different voltages: http://www.mindspring.com/~jeffpo/ledlite.htm How about a solar charged LED utility light: http://www.solorb.com/elect/solarcirc/solarfl/ A LED light project for Scouts: http://www.e-scoutcraft.com/film_can/led_flashlight.html

guest		25-Jul-2005 00:12
Really cool page, I found it while looking for info on making a LED flashlight for two nimh rechargable batteries (1.2 v each) instead of 1.5v. Does anyone know of some more info I can look at?

Khigh		19-Sep-2004 22:45
Okay I found this page because I was telling someone hooking an LED straight up to a battery is bad for the power source and the LED due to high amperage levels in comparison to the low amperage needed for an LED so lemme comment on some of the things I've seen people talk about an LED stands for Light Emitting Diode, they are well focused bright low amperage bulbs. The advantage of an LED is the fact that it takes up virtually NO WATTAGE I mean like NONE therefor power is saved and battery life is maximized. The parts needed is a low ohmage resistance (depending on the type of power you're giving it the resistance will need to be higher) if we're talking a computer power supply, normal batterys, somewhere around 50 to 150 ohms, if we're talking Lithium Ion NiCad NiMH we're talking 150 to 500 ohms or for a car battery you may even want to start off trying around 5kohms.... the reason you need a resistor is because since it is so low power when you put a battery in there, it is almost like connecting straight to ground, in other words THE WIRE OR LED GETS HOT... and SOMETHING is gonna burn out a resistance will limit the current flow which will allow the LED to not get as hot. LED's come in all differrent voltage ranges , most commons being 1.5 volts, 3 volts, 9 volts, and 12 volts, ... buy the ammount for whatever battery size you want, ..... if you buy a 1.5 volt one, and intend on using it with 3volts , then just up the resistance a lil, ..... I think this is a cool page, has some good ideas, when the white LED first came out my brother wanted an LED flashlight, so we bought a 3 volt white LED, ... and took a cheap dollar store flashlight that took 4 1.5 volt batteries.... I then desoldered the bulb just like he did and soldered in the LED, .... I didn't put the resistance in, ... I took the resistor and just shoved it where one battery went and kinda twisted it up in it...so it connected with both connections for the battery..... then the other 3 batteries were placed in it, I used a higher resistance so that the LED could handle the 4.5 volts .... flashlight works good to this day however walmart has a really nifty flashlight out thats LED driven and quite frankly I recommend it to anyone who wants one, the LED is refocused to maximize brightness... so it is very efficient and can last around a week one two double a's.... Hope this helped someone.... respectfully submitted - Khigh

dloftus		11-Aug-2004 16:26
I had someone ask me if the size of the LED matters. The one I'm using in for this demo is a large red one about 10mm in diameter. You can use any size LED and I have made bulbs using the smaller ones, it's just that they are usually not as bright. The real factor is not size but voltage. Some of the newer white LED require more volate and a different resister. Ask the electronic parts store where you buy your resistors and LED's for the proper specifications. Hope this helps.

dloftus		24-May-2004 19:46
I updated the gallery title to reflect your concerns. I use these bulbs in regular two cell flashlights, but it doesn't matter if they are D, C, AA or AAA size, just so long as you are working with 3 volts I hope the rest of the photos explain everything you need to know, like polarity of the LED and such. As for the voltage requirement of the LED, all that info is on the package. I went to the Radio Shack web site and here is the link you will need: http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F011%5F006%5F002%5F000&product%5Fid=276%2D086 Copy and paste that to the location line and it should work for you. Hope this helps

Guest		24-May-2004 03:11
Great tutorial. What I need to know is what you consider a 'regular battery' to be. Is it one with two 1.5 volt batteries? What's the purpose of the resistor? What's the minimum power source needed to drive an LED? I think it's a little over 2 volts but am not sure. -- bob

dloftus		18-May-2004 15:22
Ortis, If you click on each picture and go to the single image, there is a discription of the process involved. I believe each of your comments are covered when you read the captions at each photo. Hope that helps.

Ortis		10-May-2004 02:03
Clever project. You can buy LED replacements for flashlight bulbs, but they are expensive and not as much fun. Comments on the gallery: -Good pictures, but why are two resitors shown in the photo when only one resistor is used? -No discusion of LED polarity and that is critical -No comments on selecting LEDs and calulating the required resistor. Regards

click on thumbnails for full image