Home-made LED Conversion

Can you take an led, like the Nichia 5 mm -5600mcd,and put it in a 2 cell flashlight without any other modifications i.e. resistors, capacitors, etc.. - and will it work adequately?

If so, is it worth doing so? Anyone done this?

Thx & Happy Thanksgiving to CPFers.

agreed, although I was going to add low ambient temperatures could make it possible in some rare situations, ie you're a flashoholic Eskimo in the Yukon in the middle winter with some time to kill and you're batteries are all stale

If you put one in a 2AA light, and use energizer L-91 lithium batteries you are "in the neighborhood" of the right voltage for a while.

This is the easiest way to make a "functional" if not perfect LED light on your own.

I have a fairly extensive post of instructions and performance specs http://az123.com/LED/swivelconv/
that will give basic idea, which may be applied to a variety of 2AA lights with a little creativity, including Mini-Mags and the like.

(corrections welcome!) I think the problem there is your Nichia needs four volts to run right and 2D is only 3volts. All the best conversion lights have 3 regular batteries in series, whether they be AA, C or D. You could get a regulator and run them in most anything though. That may be more than you're interested in attempting. If you want a good conversion light look for something with 3 cells in series arrangement.

Question: Would a flashlight with 4 (1.5 volts each)batteries overdrive the same led?

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by flashlightguy:
Question: Would a flashlight with 4 (1.5 volts each)batteries overdrive the same led?

<HR></BLOCKQUOTE>

Without a resistor?-you bet it will.

The right voltage for LEDs has been discussed at lenghts in earlier threads - so any serious LEDaholic should do a search on that - and not just voltages but also the right calculation for currents, resistors and all that and more ....

For a short rundown:

The typical white Nichia LED needs around 3.4V and takes 20ma to produce its 5600mcd. It can be overdriven to 30-50ma - even more when some cooling gets aplied to prevent thermal runaway (when getting a higher current the LED gets hot - resulting in a lower resistance - and higher current - and even higher temp - and even higher current - and even much higher temp - and even much higher current - until it just dies)

The more current the more brightness - but efficiency gets lower - good mix is possibly between 20 to 30ma for most applications - BTW - you get more efficiency with lower currents.

Now how to get there:

Silvirons proposal is perfectly right - with 2 Energizer Lithiums you have a very easy straightforward conversion - take a 2AA (Mag or whatever - I used an old Mag2AA "clone" I had lying around) - plug in the LED and 2 L91s and you are done - search the Web and you´ll find some more conversion "how-to-dos" besides the really nice one from Silviron if you feel unshure on the details.

You can also take special rechargeables like 3 x 1/3AAAs for a Solitaire or 3 x 2/3 AAAs for a Micromag or 3 x 2/3 AAs for a Minimag to get a nice rechargeable 2AA / 1AAA / 2AAA LED-flashlight - just did that myself for an old 2AAA Micromag - needed to fit a resistor though as the initial 3.9 was just too high. Also reports are that a Solitaire using a tiny 12V baterry did the trick as well - conversion reports on that on Quickbeams site - also several reports on such conversions in older threads on CPF.

Typically any 3D/C/AA/AAA is an easy target for conversions as you are in the right voltage area already without any special type cells - just use the right resistor to get your voltage down to the right level.

Anything above that like 4 cells is a waste IMO as you will need to use higher value resistors to get rid of more voltage compared to 3 cell ones.

There are also special solutions to use less than three cells (like one or two) using special circuits to boost the voltage like used in the ARC-AAA. There are even special actual threads on CPF these days (and older ones as well) on that by real hacks designing circuits around chips like the tiny Zetek or National and others. Among them are also special regulator circuits giving you the a perfect regulated current/voltage ideal for the LEDs.

Oh yes - and then theres the PR-based replacement bulbs from ledtronics and others to convert 2,3,4 cell incandescent to LEDs - and such bulbs are also doable yourself.

I don´t want to get into any more detail as this has perfectly been discussed and detailed out in other places on CPF and I could only do it worse than that. I can only encourage you to do a search and spent a little while reading through this various threads to built up your knowledge - well worth it IMO.

Regards

Klaus

Thanks Klaus - Have a Happy Holiday Season and a Healthy and Prosperous New Year