Hot rodded GD board

[Greg G]

I have a couple of single 18650 Cree lights that I'd like to increase the current on. Is it possible to set up the GD board for 1200ma?

Is it ok to parallel two GD 750 boards to get 1500ma?

Many thanks,

Greg

 

[darkzero]

Although I believe it's not recommended for over 1A, I've set a GD to 1194ma with no problems. I'm don't know jack about electronics but the datasheet for the IC states 1.2A max. Don't know what that means & how the other componets come into play.

Yes you can run two of them in parallel to get a higher output. It's an expensive solution for a driver though. I've ran three GD1111s to make me a GD3333 & measured 3.35A from it. I used it in this.


GD3333

SOB3000

 

[Greg G]

I remember seeing your triple GD driver for the P7. :twothumbs

Your ~1200ma GD driver is holding up well? Does it have many hours on it? Did you heatsink it?

I'm thinking two GD750's in parallel *might* be a better solution in the long run. I'd hate to overdrive a board and have it fail onme.

I'm fearful of trying to parallel boards though. I tried it on a multi P7 light with 3 Sharks and I did something wrong along the way and smoked two of the boards.

Any advice on doing it?

Thanks,

Greg

 

[collector]

niceeeeeeeeeeeee

 

[Justin Case]

What did you use to pot those stacks? How did you keep everything parallel during assembly/soldering? What are those vertical standoff/conductors made of -- tinned solid conductor from some hookup wire with insulation removed? I was considering using some 24 gauge copper hookup wire.

For the SOB stack, how are you bringing the power from the LED+ and LED- posts to the emitter? Do you have plug-in connectors that attach to the LED+ and LED- posts? Otherwise, I would have thought that it would be better to solder in two wires for the topmost SOB board at LED+ and LED- and run the wires to the emitter. I assume that you have Conductor1 passing through each of the GND holes of the SOBs, Conductor2 passing through the matching LED- holes at J6, Conductor3 passing through the matching LED+ holes at J5, and Conductor4 passing through each of the Vin holes of the SOBs. Then I assume you soldered a post to the remaining open LED- hole on the top SOB board and another post to the remaining open LED+ hole on the top SOB board.

 

[darkzero]

Your ~1200ma GD driver is holding up well? Does it have many hours on it? Did you heatsink it?

Sorry, Greg for the late reply, forgot & missed this I guess. 😱 I personally did not put a heavy amount of hours on it but I did test it & use it fairly enough I would say. I fully potted the board, not sure how hot the board actually gets though. Never heard any issues with it. YMMV though & again, I don't think Wayne would approve driving it that high.

What did you use to pot those stacks? How did you keep everything parallel during assembly/soldering? What are those vertical standoff/conductors made of -- tinned solid conductor from some hookup wire with insulation removed? I was considering using some 24 gauge copper hookup wire.

For the SOB stack, how are you bringing the power from the LED+ and LED- posts to the emitter? Do you have plug-in connectors that attach to the LED+ and LED- posts? Otherwise, I would have thought that it would be better to solder in two wires for the topmost SOB board at LED+ and LED- and run the wires to the emitter. I assume that you have Conductor1 passing through each of the GND holes of the SOBs, Conductor2 passing through the matching LED- holes at J6, Conductor3 passing through the matching LED+ holes at J5, and Conductor4 passing through each of the Vin holes of the SOBs. Then I assume you soldered a post to the remaining open LED- hole on the top SOB board and another post to the remaining open LED+ hole on the top SOB board.

I used Devcon mixed with alumina oxide powder to pot these. You can use other stuff to pot though too.

Yes, the vertical conductors is just the same ol 26 awg stranded wire that I use for most of my builds. Removed the insulation & tinned the wires before assembly. I soldered on all the uninsulated tinned wires to the bottom board first. Then I slid the next board on till it rests against the inductor of the bottom board. Soldered the connections, then slid on the next board (with the GD stack). After that I potted it.

From the excess tinned wires joining the boards or the posts as it appears, I just soldered wires directly to them. I never use connectors with drivers & I highly recommend not using any either.

You are right again. I've got four wires passing through each matching hole joining the boards. The ground & Vin wires are cut short at the top. At the bottom I left enough wires for the ground just as I did on the top to make the ground connection.

This was fun & they work great but you may just want to wait a bit. Wayne has a SOB3A in the works.

 

[Justin Case]

Thank you. Very clear explanation and nice photos.

I probably won't use the SOB3K for my application unless I can solve the thermal management issues (essentially 2.8A into an MC-E means about 10W of power).

I'd like to drive an MC-E mounted to an AW TurboHead tower. The tower has limited space for an 0.55" driver in the base. I believe I have the space to wire the LED in 4S, 2S2P, or 4P.

If I went with 2S2P, I could use an SOB 1000 and deliver 500ma to each die. For my purposes, that would give plenty of lumens (I'm using a Seoul P4 currently, driven at 1000ma). I don't need to drive the MC-E right at 700ma. The issue even with the SOB 1000 is that the board still will be generating about 6.6W of power. Do you think that the SOB 1000 can take that without thermal management? If not, what if I potted the board a la your Big Mac approach? I could fill the AW tower driver cavity with thermal epoxy (edited: or with thermal compound, for a more easily reversible installation) and insert the SOB 1000 into the filled driver cavity. Then the entire tower would act as a heat sink. Plus, when the tower in installed in a SureFire TH, the TH would also help to conduct heat since the tower stem will be in tight contact with the TH's reflector opening. I suppose if this potting approach could also work with the SOB3K, then maybe I would be willing to try it.

 

[Greg G]

Will a Shark Buck 3A fit in your host? It will handle the wattage for sure.

 

[Justin Case]

I think the Shark is larger than 0.55" diameter.