Driver for M@g mod. I'm lost.

I want to build a m@g for a very good friend for Christmas. He's a home builder and uses his light a good bit inspecting work on homes that do not have power yet. He "had" a stock 3 D cell and lost it (or maybe it was stolen).

I went to Lowe's today and bought a 3 D cell M@g as a host. I took the switch out and found that I can fit 4 D cells in there. I'll just have to figure out a surface mount switch. I think I can handle that.

I'm going to recommend to him to run NiMH cells in it, but I'd like for him to able to stuff regular unleaded alkalines in there in a pinch as well.

The emitter will be a USWOH Seoul. Litemania heatsink. Fivemega MOP reflector. It's going to be nice. I want to drive it between 750ma - 1000ma. I'm thinking an SOB buck driver from the Sandwich Shoppe would work for this application. Am I right?

After doing a TON of reading on this board, the Sandwich Shoppe, and Taskled.com I've come to the conclusion that bucking is better than boosting, hence the 4 D configuration.

I have a machine shop and can cut threads and groove m@g heads all day long, but I get totally punch drunk on the driver stuff.

Would a simple resistor work for this? Any advice is appreciated.

Many thanks,

Greg G

3 cells is a really an easier first mod.
I recommend you first download this program. http://www.jtice.com/led_pro/led_pro.htm
and then you will be able to calculate the necessary resistor to run the light direct drive.
Or for something a little bit better still using 3 cells NiMH or alkaline try this board from DX http://www.dealextreme.com/details.dx/sku.4735
I've built a few light using this board and the configuration you described and they work very well.
Norm

The board(as well as this, but you would have to solder the output to LED wires) would work with 4 NiMh or 4 Alkaline cells at around your targeted current.

Solder the + wire to the + round center contact of the driver and the - wire to the - ring contact of the driver. Then solder the + output wire to the + contact of the LED and the - output wire to the - contact of the LED and you should be good to go(after attaching the LED to the heatsink of course).

I just built a few similar m@g mods - a 3D with 3 alkaline primaries, and a 1D from Ledean with 3 or 4 (optional) aa's. Only difference is runtime.
This driver works great and 3.6+ volts to 6 max is ideal. With 3 D primaries it's very bright and it sports multiple modes. Getting it before christmas could be tough so order now.

While using current limiting resistors is the simplest mod, the flat runtime of a regulated light is very very useful. The SOB works great for anything more than 3D but personally I prefer the smaller 2D and use an efficient boost (next gen BB). I drive the LED at around 500mA with a Seoul P4 and it still gives off very very useful amounts of light and gives hours of runtime. I haven't measured but I've had a 2D for over a year now on the same set of batteries and it gets used many times per week.