Suggestions for inexpensive mod for Boy Scout Project?

Okay I'll admit it, while this will ultimately be a project for my son to do for Webelos I have been wanting to get into modding some lights.

With that out of the way, here are the parameters I am considering;

• Easy, minimal electrical work. Perhaps some soldering?
• Readily available battery form factor (AA's, C's, D's) nothing that you couldn't find at a local store (I know, 123's are pretty easy to find but this should be something that anyone has around the house)
• Small hand held torch or headlamp
• Something where there is a noticeable increase in performance (ideally output, something you can immediately see)
• Under $30 total (preferably less in case of "failures", this will be a learning process for both of us I would imagine :mecry

I've read a few that I'll link below

http://candlepowerforums.com/vb/showthread.php?t=174070 - this may be the best place to start although it feels like cheating what with a drop in and all (besides it's a 123 light)

http://candlepowerforums.com/vb/showthread.php?t=158461 - I like the idea of this one, it's a little more work but really inexpensive so it wouldn't kill us to make a mistake.

Your suggestions will be greatly appreciated. I hope I've given enough info so you understand what I am getting at.

My hope would be this could also be something we could extend to the whole pack, where my son teaches other scouts how to do what he has learned.

thanks,

Craig

That sounds very cool. Here are my thoughts:

How about a Minimag mod, with a single high-power LED (doesn't matter what kind) DD by 2AA alk. You'd get a big decreasing runtime tail, with decent output (starts at about 150mA).

You could do this by simply getting a long 1/2" dowel from a home improvement store, cutting it into ~0.4" lengths, then making a contact that extends from an edge to the center of the other side (for the positive terminal) and another contact that touches the body tube (negative). Then you'd just solder the emitter's contacts to the proper terminals.

Alternatively, you could use a metal dowel and insulate where necessary.

If you widen the stock reflector hole a bit, just enough to comfortably fit the emitter dome, you might even be able to retain the use of the head twisty as the switch. Otherwise, you'd need tail switches.

Or, you could get a bunch of 5mm LEDs and jam the legs into the bipin holes (observe polarity by putting the short negative leg into the side nearest the tab that contacts the body tube). Trim the legs if they're too long, and keep the reflector in there to act as the switch. This setup draws a whole 7mA. Assuming you get only 2Ah out of a pair of AA alks, this would last over 250 hours.

So, you could do something very cheap (where the main cost is the Minimag) and ridiculously easy for very low output (between 1.5 and 2 lumens, very useful for night-adapted vision), or something slightly more expensive, more time-consuming, and brighter.

5mm: Minimags, 5mm LEDs, $8/ea, 5min/ea
Power LED: Minimags, Cree/Seoul/KLC8/etc., $15/ea, 30min/ea

I hope some of this helps. Keep us updated!

well, if You liked the idea of the 2nd link but did not like the batts of the host light,
then why not "just" get another one from this seller - with a batt You like?
(f.e.: http://www.dealextreme.com/details.dx/sku.1120),

get Seouls mounted on Stars and open light, solder old led out, mount new star and solder it in - ready.

I ve done it to this special light and its a breeze
(problem were the lousy treads and that the head has to be defocused to get a good spot and gets wobby then, should have putten some kind of foam or similar into also.

Of course You could also search for a light more similar to the CR123 light but running on AA cells (would feature smaller head)

TigerhawkT3 said:

How about a Minimag mod, with a single high-power LED (doesn't matter what kind) DD by 2AA alk. You'd get a big decreasing runtime tail, with decent output (starts at about 150mA).

Click to expand...

Don't know about the lack of voltage with that. How about using NiZn/NiOOH or maybe lithium AAs instead? Slightly higher starting voltage.

That's a great idea for a Boy Scout project. You can frame it as building a light that will be used on future outings and for emergencies. You might even be able to get a CPFer to donate a batch of lights and/or parts to your Boy Scout troop. (It's tax deductable isn't it?)

Maybe you can do Maglites and simply swap out parts... Kaidomain reflector, UCL(tm), LED dropin or maybe potted Welch Allyn lamp?

Or you can have the Scouts fabricate their own lights from PVC or paper towel tubes heh...

scott.cr said:

Or you can have the Scouts fabricate their own lights from PVC or paper towel tubes heh...

Click to expand...

Yeah, that's good fun. I made a 12 LED torch in a toilet roll tube a couple of years ago. Cannibalised it for parts eventually, and I don't mean the toilet paper (there wasn't any).

I can't find the link anymore, but you can build a LED flashlight with a 9V battery, a resistor, a switch, and a LED of any color and fit everything into an old round film canister. It's a fun project and it gives out light for a loooooooooooooooooong time.

You poke the LED and the switch contacts through the canister cap, hook the wires, the resistor and wire the battery. You don't even need solder (but make sure to isolate the contacts). Shove the battery and the cables inside the canister, and close it up. Look, Pa, a flashlight!!


HA! Found it:

http://www.e-scoutcraft.com/film_can/led_flashlight.html

Lots of fun. My son still has the blue LED one he built.

greenLED said:

Lots of fun. My son still has the blue LED one he built.

Click to expand...

greenLED's son makes blue LED torch. LOL.

Quite a while back I used a ubiquitous green Eveready 6 volt lantern light for a led conversion. Two fifty at Walmart. Mounted 12 white leds on a small piece of 1/16th plywood in the reflector, hot glued it in. Ran power wires back to the battery. I wired in a 12 volt 1.2 amp hr sealed battery and used it for a camping light. I was always planning on adding a external charging jack, just didn't get around to it. Got a little warm, but nothing ever melted or burned up. I probably should have added a resistor, but didn't. I got the led's from All Electronics pretty cheaply. I think I ran the led's in a 4 serial, 3 parallel string.

That's a fairly cheap project, and back when I did it you had to pay close to a 100 bucks for one from CCrane. Now you can get a 3AAA light from Atwoods that does the same thing for 5 bucks.

Actually, that wouldn't be a bad graft. 1 cheap 3AAA light as a donor, led's installed in a ubiquitous green 6 volt Eveready lantern with a 3 cell AA, C or D holder tucked inside.

TorchBoy said:

Don't know about the lack of voltage with that. How about using NiZn/NiOOH or maybe lithium AAs instead? Slightly higher starting voltage.

Click to expand...

It will work. Current on two fresh alks is about 150mA.

TigerhawkT3 said:

It will work. Current on two fresh alks is about 150mA.

Click to expand...

Sorry, I thought you were talking here about modifying an AA torch. I would expect the D cells you used in that other thread would have a little less voltage drop than AA cells will.

The Elly Cree mod, except with a Rebel 80.

Elly, Rebel 80, Unsolder the Generic LED and solder on the Rebel LED and apply a bit of thermal paste/Glue for a thermal path.

TorchBoy said:

Sorry, I thought you were talking here about modifying an AA torch. I would expect the D cells you used in that other thread would have a little less voltage drop than AA cells will.

Click to expand...

150mA isn't much. AA alks wouldn't have any problem with that, and if they did, the decreased voltage would lead to lower current draw. In a nutshell, using D, AA, or even AAA doesn't really affect this mod.

TigerhawkT3 said:

150mA isn't much. AA alks wouldn't have any problem with that, and if they did, the decreased voltage would lead to lower current draw.

Click to expand...

That's my point. 150mA isn't much, and the decreased voltage ... oh, you know the rest. That's why I suggested something with a tad more voltage. They'll arguably be usable for more of their life, too. But whatever.

TorchBoy said:

That's my point. 150mA isn't much, and the decreased voltage ... oh, you know the rest. That's why I suggested something with a tad more voltage. They'll arguably be usable for more of their life, too. But whatever.

Click to expand...

Since an L2D-CE pulls about 220mA from alks on Medium, and gets a runtime of about 7 hours, 150mA would probably give from 10-15. 150mA from a Cree/Seoul/etc. is really pretty good (assuming 70L/W, 3V*.15A=.45W, 70*.45=~30L). But yes, you're definitely right in that using e2 L91s or similar, which provide more voltage with the current capability to match, would be a much brighter setup, delivering about 5-700mA. Heck, it could be like modding a mod for even more output.

Whatever project they end up doing, those scouts will love this! :thumbsup:

What about a 5, 8, or 10mm red LED, a resistor, and a $5 Rayovac or Everyready 2D for an "Astronomy Flashlight". Yeah, too bright for real astronomy, but great for trips to the latrine on weekend campouts. You can also have him frost the LED with #60 or #80 grit sandpaper. Another plus is that it's unusual, and the other scouts will be envious (voice of experience
If I were doing it again, I'd have him mount the LED on a dowel or pencil, and cut it to fit in the bulb socket, then hot glue it to place. Run copper wire to the battery - 22 or 24 gage should be enough.

Check out Instructables.com also.

greenLED said:

you can build a LED flashlight with a 9V battery, a resistor, a switch, and a LED of any color and fit everything into an old round film canister.

http://www.e-scoutcraft.com/film_can/led_flashlight.html

Click to expand...

This was a really cool idea, I printed out the page and my son was very excited about it! The only problem is now, trying to get all the stuff lined up.
We went to Radio Shack and picked up most of the stuff. The problem we are having now is finding the right match of LED and resistor. I really wish he had put RS item #'s on his instructions so I could just know what works and go from there.

I think I have the formula down to figure out the correct resistance for a given LED/LEDS but you can't buy them individually. Any suggestions on general LED/Resistor combo's and a cheap place to buy them?

EDIT: I just found this site http://ledcalc.com/ and I think it gives a pretty good idea of what resistor is closest to your needs.

Thanks again for all the suggestions. Once again I am really pleased by everyones enthusiastic and helpful responses.

BTW, getting the film cases is SOOOO easy, just go the any film processing Kiosk (Wally World, Costco, etc.) and just ask for them. My local wally world gave me a BAG FULL. Make sure you specify the black ones with the grey cap, the white clear ones won't fit the 9V.