HELP 3-d maglite conversion

this is my first conversion so i'm sort of "bench racing" the idea.If any of you are like myself we have a few 3-d cell maglites because of the good deal they are at the local Sams club.

i have a few sets of parts for the satcure kit but i think this will work just as good you guys let me know.

each cell in a d maglite are 1.5 v each.a std nichia 56oomcd led needs 4.5 v @40ma.so 3 d-cell batts @ 1.5 v each makes 4.5v.4 nichia's in parallel should be brite and last long.at least in theory.
what i don't know is will the led's pull too much amperage.the d cells should have plenty of power for the leds to eat.do i need a resistor or a diode.approx how brite would it be and how long would it last.

i have a lightwave 2000 with green leds it should be as brite as that at least.thanks guys and dont be afraid to get creative on me.i you give me a schematic i can build it!!!

i should have paid a little more attention in my high school electronics class for the theory.

thanks.MIKE

It's a wonderful idea and, I think, has been done before. You probably won't need any resistors. The Trek7 doesn't use any and powers 7 LEDs for about 40 hours. (And that's using C-cells.) You will probably get so much run time out of 4 LED 3 D-cell set up that the batteries will rot before you are through with them.

Be a little more daring. Squeeze 30 LEDs in to the head, complete with reflectors. See if you can devise a way to focus it to gain a long throw.

thanks Steelwolf if you know where i can get these real cheap let me know,otherwise i can't afford it.although maybe just maybe the gas bill doesnt need paid this month after all its hot in ohio this time of year.

but seriously where can i get those leds you speak of!!!

Mike,

My Hybrid Blaster needed a 0.3 ohm resistor to calm down the current. 20 LEDs and 3 D cells. It started OK at first, but after a short time, the current started to rise into the unhealthy range.

If you can get a diode with a 0.2v drop, that should be the equivalent to the 0.3 ohm resistor (0.7amp * 0.3ohm = 0.21 volts).

Let us know how it turns out.

You wanting LEDs cheap? I recommend www.whiteleds.net also. Paypal account helps, but I think he takes checks or money orders also.

thanks guys I've got 10 leds on the way from whiteleds.so i need a .3ohm resistor.is it just me or does that seem really hard to find?

Mike, try this guy. I haven't bought from him yet, but some of the other forumite have, and they have nothing but good things to say about him. They also say that the LEDs are the Nichia 5600mcd types. I'll probably get round to buying from him once I get my PayPal confirmation numbers.

i could not find a 0.3 resistor ,not in Maplins book anyway.

Gadget , did you use a resistor or a diode ,which is best to use , and how do pick the right diode ,,,,

and how do you work out what watts the resistor has to be , i did read it once but did not right it down ,,,

Thanks Ant

Guys, sorry I didn't elaborate more.
You need a resistance value of approximately 0.3 ohms, or a drop in voltage of 0.2 volts or so.

You will have to experiment with different resistance values until you get the current through the LEDs that you desire.

To find a 0.3 ohm is tough, but you can use a few standard values in parallel to get the same effect.
This look familiar?


When resistors are joined in series, you just add them, but parallel uses the above formula.

So, if you take 3 standard 1/4W 1 ohm resistors and join them in parallel, you get one 0.333 ohm resistor that can handle 3/4 of a watt. At 4.5v, and .75 watts, the resistor bundle can handle 167ma.
Watts = Amps * Volts
or
Watts = Amps^2 * Resistance

If you need it to handle more current (like 10 leds at 35 ma each) you need it to handle 4.5v * 0.35 amps, or 1.6 watts. This would require 7 resistors in parallel (7 * 1/4 = 1.75 watts).

This is quite a few resistors, so I thought a diode might be a better choice. I can't recall how much voltage drop they have though. Basic diodes can usually handle about an amp of current. I think their v-drop is about 0.2 v.

My 20 LED light uses 3 D cells. If I run it without the resistor, it pulls 900 ma and slowly rises (heat problem). With the resistor, it runs at a steady 730 ma, about 35ma per LED. The battery voltage drops to 3.6 v under load so I'm dropping about 0.1 v over the resistor (3.5v to the LEDs). This is just enough to keep the LEDs from overheating and drawing more current.

Hope this clears things up a bit.

You gearheads and engineers who insist on shoehorning a LED into a 3 cell MagLight are missing the whole point of a 3 cell MagLight.

IT'S THE POWER, STUPID!!!


You can run a REALLY bright lamp for 10-12 hours. If you want something that runs for weeks, get a 1.5V green Photon (put a 2032 battery in it instead of the two 2016s). Otherwise, you end up with something which has 1,000 times the weight and bulk and can stay on for even longer.

Jeez. You wankers keep this up, and I will start a petition to repeal Ohm's Law.

Walt

hey Walt did you ever just want to do somthing bec you can?well i did enuff said?
i didnt bash anything you've done.i know there's more light to be made.maybe next i'll put streamlight lamps 10 of em in a maglite.that would be brite.

the question was not how brite it would be but that i wanted it.

hey everyone check out new thread on 3-d craftsman lite.there's my progress.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Walt Welch:

Jeez. You wankers keep this up, and I will start a petition to repeal Ohm's Law.

Walt<HR></BLOCKQUOTE>

Great! I'll get on the horn to the Daystrom Institute right away and let them know that Ohm's Law is in some serious danger.

Emergency! Emergency! Beam me up, Scotty. Ohm's Law is being cancelled on this planet. We can no longer exist here. Get us out quick!

What about Mho's law?

nyuk nyuk!

OHM?OHM ARE YOU THERE?
GROUND CONTROL TO MAJOR OHM?
FOR THE LOVE OF OHM PLEASE DONT GO!!!

Walt one more thing if you insist on taking a Law by all means take Murphy's Law.

Hey Guys just on a ball park does anyone have a rough idea of how long the 3-d cell 4 nichia led lite would run???????????