Mag 2C + Pila 150A + Downboy 1250 + TV1K

Mr. Darkzero built a Downboy 1250 for me. This is my second "mod" that required soldering and Darkzero was a wealth of information and assistance. Thank You Darkzero /ubbthreads/images/graemlins/buttrock.gif

I mounted a TV1K on a Hotlips. I still need to pot it all up and finish the emitter solder, but this was some testing before I epoxied it up.








And a few beam shots. Lights are @ 36" from the wall. I don't have another 3 watt to compare it to. I know the Pila GL3 is not a fair or equal comparison, but.......






It throws a tight spot a good ways. It has a tighter spot than my 5 watt Mag but throws about the same. I couldn't get the tailcap spring to touch the - of 3 123's to take a pick. I was in a hurry to get it done. I'll try to do that tonight or this weekend.

Can you explain how this works? You mounted the bare Luxon on the hotlips, I see that. But I also see the circuit board (Downboy) below it. What is that for? Can you take different angle shots so I can see how it is wired?

have you measured the current from the tailcap yet?

Sounds like a great mod. Will the Pilas dip below 1250ma pretty quickly though?

Great to see it's coming along! /ubbthreads/images/graemlins/thumbsup.gif
More beamshots please if you get the chance. /ubbthreads/images/graemlins/poke2.gif /ubbthreads/images/graemlins/grinser2.gif
I can't wait to get my Mag bodies back so I can finish my very own regulated mods as well.


[ QUOTE ]
Wildcat said:
I couldn't get the tailcap spring to touch the - of 3 123's...

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Whenever I use 123s in a Mag2C, sometimes the stock tailcap spring comes in contact with the 123s and sometimes they don't. Battery brands play a role too. I always modify the stock spring just because.

I cut this one short because I didn't like all that tension of the spring, makes it hard to screw on the cap. Since 123s are very light compared to "C"s I'm not worried about the light shutting off when tapped or dropped (what the strong tension of the spring is for) because of the shortened spring.



Just for reference, every DB1250 that I've built using a LuxIII with a vf of "J" measured well into 1.3's, close to 1.4A at the emitter. I'm not sure how much current it drains with different types of batteries though.

The current at the tailcap is @ 900ma. At the LED it 1.4A. I haven't done a runtime test yet. After I get everything potted and finished up, I'll give it a test.

I'm not sure exactly how the Downboy works. All I know is it limits the amout of current that the LED gets. 8.4v would blow a Lux III.

I trim the tailcap spring to fit the 150a's. They are a little longer than 3 123's so the spring it to short for the 3 123's.

Wildcat, it looks like the black negative wire connected to the LED is also touching the hotlips heatsink. There's a good chance that the Hotlips is connected to the negative end of the batteries. I believe that when running a Downboy the LED ground and battery ground should _not_ be connected. I have no idea what the effect of this is, I just know it is not recommended.

darkzero, I have a downboy 1000 in a 2D Mag running off 6 AA NiMHs and it gets a little over 8000 lux at 1 metre for 2.5 hours. My next task is to get over the 10000 lux mark. Do you know what kind of lux you are getting when driving the LED at 1.4A?

sygyzy, the circuit board connected below the LED is a current regulator - in this case a Downboy. The downboy supplies a constant current to the Luxeon where the input voltage (in this case about 7.4V from the two Pila 150S batteries) is higher than the required output voltage (which is around 4V across the Luxeon at this current). The advantage of using a current regulator as opposed to direct drive is that you get constant brightness for the life of the batteries. So this combination will produce a good 9000+ lux for around 2 hours at a guess. Note that you wouldn't want to use direct drive in this set up. 7.4V across the Luxeon will probably fry it. The downboy has 4 wires connected to it. The input from the batteries and the output to the Luxeon.

Jeff.

balrog, the wire is not touching, it's just an illusion in the pic.

Sorry about that. When I look back at the side on photo it clearly can't be touching. /ubbthreads/images/graemlins/ohgeez.gif

I'd really like to know how many lux this setup makes at 1 metre. It's inspired me to do something similar.

Balrog - Can you adjust the Downboy to output the exact amount of current you want/need?

The output current of the Downboy is determined by the sense resistors that are soldered on to the board. The sense resistors are tiny surface mount (size 0603 I think) ones that, like the Downboy convertors, can be purchased from the Sandiwch Shoppe. There is a web page at the shop that helps you calculate the required resitors for a desired current. On the board there is room for two resistors in parallel. Using two 0.1ohm resitors will give an output current of 1000mA and this would be called a Downboy 1000. To get currents greater than 1A you need to solder on more resistors in parallel by piggy backing them on the other resitors and soldering them in place. eg, to get a Downboy 1250 you would solder on 3 x 0.12ohm resistors.

You can't adjust the current once the flashlight has been built, unless of course you remove the sense resistors and put different ones in place. However, once the Downboy has been epoxied into place with Arctic Alumina for heat sinking purposes, it's gonna be very difficult to change the resistors.

[ QUOTE ]
balrog said:
darkzero, I have a downboy 1000 in a 2D Mag running off 6 AA NiMHs and it gets a little over 8000 lux at 1 metre for 2.5 hours. My next task is to get over the 10000 lux mark. Do you know what kind of lux you are getting when driving the LED at 1.4A?

Jeff.

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Sorry I do not have a Lux meter yet so I couldn't tell you.

However, I did make a DB1194 TV0K McLuxPR head for someone and he got some numbers for me. This is what he said:

DB917 - 1,950
917L1 - 2,570
DB1200 - 2,980

Notes: Measures vary slightly from one reading to the next, these are sort of average readings, Meterman is set on x10 scale.

DB917 is a McGizmo DB917 that has a slight blueish tint, I don't know if tint affects the Meterman measurement [but it might]. This is the light I used in the off-base first measurements that I sent you.

917L1 is McGizmos 917 Two Stage mod of SF L1, it has a slightly yellowish tint compared to the 917B [much like your head does].

DB1200 is your head [of course].

Thanks

Thank you for that answer. It has made things alot more clear.