Which circuit to use?

Hi guy's, i'm having a go at my first modified lux III(TYOK)mag which uses a regulating circuit. I have a 2D maglight which i plan to run from 6 AA 2100 mAH nickel-metal Hydride cells. I will be running them in 2 of Wayne's new 3 to D AA battery holders. Now since each AA cell put's out about 1.2 volts that would equal about 7.2 volts in total. So my question is this, would the Downboy 700 rev 2 converter be an appropriate circuit for this application? Also what kind of run time would you expect from this combination? I know everyone always asks about run time and there are so many variables that will affect it, but if someone could give me a very general and rough estimate that would be very much appreciated. Also is there a way to slightly boost the output from 700ma to 1A on these boards? Thanks for looking guy's and any input you can contribute. /ubbthreads/images/graemlins/thumbsup.gif

with respect to wanting 1A you can get the downboy with whatever 2 resistors you want, 1A is easily done, it is called downboy no sense resistors or something like that.

Thanks Blue_Shift i didn't realize that you could customize the circuit. I just ordered a blank one that will be set up to run at 1 amp. Not only that but while i was using the resistor calculator on the site to figure out which sense resistors i needed, i also realized that there was a runtime calculator also. So assuming i entered all the data correctly i should be getting about 21 hours of runtime from it, which will be absolutely awesome! /ubbthreads/images/graemlins/buttrock.gif The calculator can be found here. The numbers i plugged into the equation were as follows:

Desired LED Current (in Amps): 1
LED Vf Voltage (in Volts): 3.6
Battery Input Voltage (in Volts): 7.2
Battery Amp/Hr capacity (in Amps): 12.6

Not sure if i did the math correctly on the Amp/Hr, i am using 6 2100 mAh AA cells in series so that should give me 12600 mAh divided by 1000 should give me 12.6 amp hours right? Anyway thanks for the info and i hope this is useful for anyone else with a similar question.

Your batteries are in series, so no, you don't get 12.6 AH, you get 2.1Ah.

Thanks evan.. that makes a world of difference. 3.5 hours still seems pretty acceptable for 6 AA batteries.

2.1AH x 7.2 v = 15.12 WH.. divide that by power at the emitter (3.6V x 1.0A) = 4.2 hr.. and multiply by efficiency.. estimate 85% = 3.57 hrs.. my ¢¢... get a bigger SO20XA or SO27XA reflector.

Excuse my ignorance but i've never really dabbled with different reflectors before. Will those reflectors you mentioned fit nicely in my mag head? And if so where can i get one?

the SO2xXA reflectors are all too smal - the numbers indicate the diameter in millimetres.

neg

oh.. i failed to mention.. it might 'look a little funny'... the SO27XA is just about an inch in diameter so it would only fill the center of the lens area of a Mag, but i'm willing to bet it'd be a better looking beam.

My megasonic light for example, is 3.6 inch diameter, but i used 3 SO17XA reflectors and they fill approximately 10% of the area, and the light wash is beyond wonderful.

-awr