Solitaire mod: What voltage do 3mm LED's forward bias at?

In the process of trying to stick a red 5mm LED into my Mag Solitaire, I noticed that the AAA battery won't forward bias the LED. Just a tiny red light in the center when in correct polarity.

So I'm thinking of using a 3mm LED instead. Plus I won't have to drill the reflector. Will it be as bright with a 3mm as with a 5mm?? What voltage will it forward bias it? Will it work? Thanks.

check the spec sheets on superbrightleds.com for details.
IIRC, red has lower Vf than other colors, but still much higher than 1.5V (so, no, your stock AAA won't light up the LED). You need a li-ion AAA or a 12V batt (from those garage openers); I use a resistor for the 12V (although not critical due to batt's internal resistance), the li-ion would run DD.
The 3mm LED won't be as bright as a 5mm one.

THanks for the info. I really want to run an LED off of a regular AAA battery. Sounds like it's not doable. THanks anyways.

No can do without adding electronics (DC to DC boost converter) the Vf does not change between a 5mm and a 3mm.

I noticed this one:

5mm Nichia Pocket Light (AA X 1)
http://emilionworkshop.com:3072/osc...d=302&osCsid=c7ad1f1a45378388319a57f97061e8cd

So how does this one work with a single 1.5V AA battery and also have a "long runtime"?

I don't have that light from Emilion, but there are plenty of lights out there that are easy enough to modify with one or more red LEDs. Are you wanting long runtime or brightness?

I haven't come across any really bright 3mm red LEDs though I have a few bright 3mm green LEDs. The reds are usually speced at 2.4 Vf while greens and blues are usually around 3.4 or 3.7 and run decently one just two 1.2V cells.

I saw some low volatege LED's at Digi-Key. They are ment for operation in low voltage DSP circuits. They prolly have a little charge pump inside. Go here:
http://www.digikey.com/

and search for "dsp led".

cratz2 said:

I don't have that light from Emilion, but there are plenty of lights out there that are easy enough to modify with one or more red LEDs. Are you wanting long runtime or brightness?

I haven't come across any really bright 3mm red LEDs though I have a few bright 3mm green LEDs. The reds are usually speced at 2.4 Vf while greens and blues are usually around 3.4 or 3.7 and run decently one just two 1.2V cells.

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Preferably brightness.

Any 1xAA or 1xAAA light will need a boost circuit. There's no other way to increase the voltage to power the LED, especially if what you want is "brightness".

You could also get into rechargeable battery combinations, (eg. 3x1/3AAA), but IMO it's just not convenient (need spacers for the batts, hard to find, etc.). I think I also mentioned in another thread that you could use a AAA li-ion battery and run the LED on DD (direct drive). Since you're using a 3 or 5 mm LED, be really careful not to overdischarge the cell or you'll damage them. You need a li-ion charger for them, BTW.

I started with these types of mods on a Soli, but I've moved onto bigger lights. It's easier to find power sources and battery combinations that will power LED's.

In most of my soli mod's I have the li ion 3.7 AAA, resistored, and get a lot of brightness from 26K, 35K, and nichia CS's. I still got a couple of the M21/23
batt ones too. you may be able to get a lamda micro pill soon for the soli, but the light will need to be bored out.

There is another company that will have a soli module soon too. I have done a lot of experimenting with the reflector's and sent some to this company.

there is the techtite LT-3 too ,but i have heard opinions that it's not real bright, to it's about equal to 35k 5mm. You can run a search on my name and solitaire to read a little on how I modded mine. The reflector in the soli really is a very good match for a 5mm, not sure about a 3mm, but nine are brighter and throw better then an ARC AAA-P. But then again, it's running on a hotter battery.

I don't know why I bother with soli's when there are so many good 1xAAA out there (most of which i own) but I guess it's my gateway light to learning about flashlight builbing knowledge. VDG

I was really hoping to make a cheap Solitaire LED. Just a dropin mod that will make my Solitaire useful as a maplight or low intensity around the house at night light. I'm not planning on using 3.7V batteries or anything. I was just hoping to get a 3 or 5mm LED running off of a standard 1.5V battery, otherwise it's not worth it to me at this particular time. Thanks anyways though for the input. I'm always happy to learn all I can.

InfidelCastro said:

I was really hoping to make a cheap Solitaire LED. I'm not planning on using 3.7V batteries or anything. I was just hoping to get a 3 or 5mm LED running off of a standard 1.5V battery, otherwise it's not worth it to me at this particular time. Thanks anyways though for the input. I'm always happy to learn all I can.

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nothing wrong with a simple soli mod. Just go with the mn21/23 for now. If you dig it you may feel up to making more, with different styles of construction. That's how i got addicted to modding soli's. just have fun!! VDG

What is mn21/23?

I've heard of LED's with 21,000 brightness, is that what you're referring to?

Here:
http://store.yahoo.com/zbattery/mn21b2.html

It's the 12v battery used in the flashlight reviews solitaire mod 1 and mod 2.

Wall mart carries them, in the camera/music/electronics area. VDG

Here's the mod I did for a Soli. 3mm 25000mk LED. Runs off of 3 AG4(LR66) so im hitting it with between 4-4.2v. The LED fits into the reflector and bi pin socket without any modification. I built a battery holder with a piece of plastic tubing and made a spacer with a piece of 1/4" copper tubing. Simple and you can buy the batteries in multi packs and discount stores.