flashlight mod

looking to convert a few 2d cell bulb flashlights to led. I am not having much luck searching the forum. There are a bunch of broken links. First time modder here looking for schematics to wire a few leds to replace the bulbs in a few 2d cell flashlights. I would also be looking for a good source for leds in bulk. I am doing this as a way to learn a bit more about leds and flashlights. any help is greatly appreciated. Thank You
Tom

Introduction to modifying flashlights: http://www.candlepowerforums.com/vb/showthread.php?257554-Introduction-to-modifying-flashlights

Review that, and do some searching based on the things that thread talks about, and then come up with more specific questions.

Thank you for the reply. Interesting read, but I am looking for something that incorporates the lower end cheaper leds. Maybe 3 or more wired into the 2D cell flashlight to replace the incandescent bulb. I am not quite sure how to wire more than one together. And I think a resistor may be needed somewhere. This is the led I am looking for in bulk. White, Good price ad I prefer really bright smooth beam.

See Rule #3 Do not Hot Link images. Please host on an image site, Imageshack or similar and repost – Thanks Norm

That won't give you a beam. It will be smooth. It won't be really bright either.
So you'll get 1 out of 3 wishes.

Just use a real power LED. Cree XRE cost a couple of dollars. Fix to the simplest heatsink and you will be far better off.
Either run on low enough voltage that you don't need a resistor or add resistor.

OK, see your bank manager and see if you can stretch to $3.33

http://dx.com/p/cree-p4-emitter-on-12-8mm-base-5991

Here is a spreadsheet with info on online stores that sell leds. I wouldn't particularly recommend dx or kaidomain. As chodes said, you can get a good led on a star for only a few dollars. Two D cells wont give you the voltage to run an led without a boost driver.

Hoop said:

Here is a spreadsheet with info on online stores that sell leds. I wouldn't particularly recommend dx or kaidomain. As chodes said, you can get a good led on a star for only a few dollars. Two D cells wont give you the voltage to run an led without a boost driver.

Click to expand...

It might... (2 cells...)
Variables are LED Vf and light resistance.
Surprise examples I found:

In a direct drive low resistance triple SST50 light I found:
3 CR123 primaries resulted about 270ma. Quite a useful amount of light as backup to the usual 5-6 Amps on 3 x IMRs.
2 x IMR 18500s resulted in about 100ma. (with 3 LEDs, this was almost as much light as a 2D Maglite)

With the 2 x 18500 example, assuming 8V made it to the LEDs, divide by 3, only 2.66V for each SST50 for useful light. I doubt 8V made it to LEDs..
That's why I say depending on LED, 2 cells may work. Remember OP wants super cheap solution, 100ma through a Cree beats 3 5mm LEDs anyday.
If LED does not glow, 3 cells and resistor next step.

The target to beat is 3 x 5mm LEDs. If the Cree glows, that's enough.

Thank You all for the info.