NBv2 + PEX wiring check?

[Whi-ja]

Um... Help, please!

I have wired NBs before (successfully) and uses the PEx for FoC. No problem.

I wanted to use the transistors on the PEx to allow me to fully drive a quad-Cree LED setup (GGRbRb).

Now the board seems to have a feedback loop causing it to heat up and hum like a little, tiny power line transformer box.

I wired it according to the images. (pic one is the wiring diagram minus the PEx hack that I sketched at the bench prior to soldering; the second indicates how I wired the PEx and NB and was done separately from this build.)

Before the cram-fu stage (and with no LED attached), I applied power to the circuit to test, inserted the SD card, and pulled the kill key. Boot sounds, power on sounds, and clash were all good.

But as I went to insert the chassis assembly into the hilt I sensed the heat on the board. Of course I immediately pulled the battery from its pack and pulled the SD card. But unless I troubleshoot this, I'll burn out the board in no time.

Did I perhaps short out two components on the board? I an an experienced solderer and was very careful... Or so I thought.

I can't get pics of the actual board without desoldering a few wires due to the chassis setup, but I'll do that if the diagrams aren't enough.

Hopefully someone here can help. Thanks in advance for any advice. 1114211141

[Silver Serpent]

You're stacking PEX's to safely drive more current, right?

Wire up the LED dice in sets of two, and connect half of them to the board, and the other half to your extra PEX. You don't want to connect the PEX output back to the board.

[Forgetful Jedi Knight]

First off, what kind of current do you think your going to get? And what type of battery are you going to be using? NB's are NOT designed for stuff like this.

[Silver Serpent]

I've seen this recommended by erv himself before, so it's not entirely crazy. :)

Definitely want an 18650 for the current draw you'll be experiencing.

[Whi-ja]

Thank you for the replies.

I'm using a TCSS 3.7V 18650 battery and looking for four dice at 1000mA each.
Each of the dice is a Cree XPE-2 (2x green, 2x blue) resistored for a 1A current draw at the prescribed Vf.

I'll work up a complete wiring diagram sometime today.

I really value the expertise of anyone who is better versed in microelectronics than I am, and especially as I conduct this first-for-me trial. I have heard of others using this technique, but their responses via email have been slow, and, frankly I implicitly trust the folks on this forum, as this is where I started to study and practice saber building. So thank you for the feedback.

[Silver Serpent]

http://www.fx-sabers.com/forum/index.php?topic=44734.0 is where I first heard of doing this. There's a diagram in that thread somewhere (though my work firewall is blocking it) that you may find useful.

Heat is still going to be an issue. FJK is right, this board wasn't really designed for this purpose. You can make it work, but it's going to take some tinkering.

[Forgetful Jedi Knight]

Thank you for the replies.

I'm using a TCSS 3.7V 18650 battery and looking for four dice at 1000mA each.
Each of the dice is a Cree XPE-2 (2x green, 2x blue) resistored for a 1A current draw at the prescribed Vf.

I'll work up a complete wiring diagram sometime today.

I really value the expertise of anyone who is better versed in microelectronics than I am, and especially as I conduct this first-for-me trial. I have heard of others using this technique, but their responses via email have been slow, and, frankly I implicitly trust the folks on this forum, as this is where I started to study and practice saber building. So thank you for the feedback.

Which mAh rating specifically? Most batteries can't throw out a 4A current, plus the fact that the board wasn't generally designed for this are the main reasons why it isn't generally done. I haven't seen a FULL Quad run off a NB. The concept isn't crazy, per se, but that wiring looks wrong, and dangerous.

EDIT: I'll look into this and get back to you.

[Whi-ja]

Which mAh rating specifically? Most batteries can't throw out a 4A current, plus the fact that the board wasn't generally designed for this are the main reasons why it isn't generally done. I haven't seen a FULL Quad run off a NB.

EDIT: I'll look into this and get back to you.

Thanks. For now it's sitting on the bench, ready for reassembly built on the feedback I get here.

[Whi-ja]

Well, I've usually just driven 2x 3W dice off the boards.

I've had a lot of trouble finding a way to boost for 3 LEDs at full power.

Would it help resolve the issue if I reduced to three dice (a GGW Cree XPE2, for instance)?

[Forgetful Jedi Knight]

Driving 2 of any dice (as long as they are properly resistored) and using the third as a FoC is an "ideal" setup and use for a NB.

[Whi-ja]

Driving 2 of any dice (as long as they are properly resistored) and using the third as a FoC is an "ideal" setup and use for a NB.

Yes, the "textbook" method, so to speak. But what are we if we don't try? ;)

[Whi-ja]

Silver Serpent:

Yes, I can't seem to get the image to load, either. But thank you SO mch for the link. I searched in vain for just that type of thread earlier this weekend.

I'll try the image download again when I get home.

[Forgetful Jedi Knight]

Yes, the "textbook" method, so to speak. But what are we if we don't try? ;)

Usually, you would remain in one piece to build sabers another day.

Well, since you seem intent on this, good luck.

[Whi-ja]

I appreciate your candor and input as always, FJK.

The link SS listed includes a suggestion for a similar method from Erv, but it looks like his current draw is still close to 2A. If that is the case (and who would doubt Erv?!), I'll start by moving back to a GGW tri-Cree (running around 650mA each) and away from the four dice concept.

Nor am I averse to scrapping the idea and using a more traditional setup. I'll let you know the end result, even if it means abandoning my "wild aspirations". Happy sabering!

[Whi-ja]

I was able to find the diagram Erv posted at the link SS sent:
11147

It the same as my 2nd diagram, but without the led or battery indicated.

I'll draw a full wiring diagram ASAP and post it here and on FX-sabers for review.
I actually tried to recreate the fault that cause me to write this post, and so far I can't get the circuit or battery to warm up at all.
I'll also try to power a GGW tri-Cree at 1000, 1000, and 350 mA respectively and see if the battery or board start to get warm or give any other indications of a fault (ie PCB shutting down the circuit).

[Forgetful Jedi Knight]

You should be able to run the White at close to 1A with that setup. The wiring is OK, now that I have seen a bigger version of the pic. I hope you are going for a "Veridian Green" type color, because that's what you are going to get.

[Whi-ja]

Your thoughtful consideration and careful skepticism are exactly the kind of strict analysis and objective criticism I am looking for.

Viridian is exactly what I'm hoping for, but the big question is the circuit's load capability. I'm at the bench right now wiring up a 1000-1000-700mA (G-G-W) setup to test it.

I think that my original problem was insufficient insulation of the wires soldered directly to the board - when I went to insert the chassis, the tight space allowed a small part of the wires to short with another component. At least that's my best guess at this time.

[Forgetful Jedi Knight]

If you resistor things properly, you should be able to safely pull around 2.7A out of the battery.

[Whi-ja]

I'd say that's a pretty shade. ;-)

11149

White around 350mA, greens at 1100mA each (if my resistor math hasn't failed me). Booyah. And no unusual heat on the board after I insulated those connections.

Wiring diagram will be in a new post. Thanks, FJK, Erv, and Silver Serpent!

[Whi-ja]

FJK, it seems you've had this discussion many times with us over-eager entry- and mid-level saberers (see link).
Thanks for your patient tutelage.

http://forums.thecustomsabershop.com/showthread.php?16611-NB-2amp-output

[Forgetful Jedi Knight]

FJK, it seems you've had this discussion many times with us over-eager entry- and mid-level saberers (see link).
Thanks for your patient tutelage.

http://forums.thecustomsabershop.com/showthread.php?16611-NB-2amp-output

And yet the conversations always seem to go the same way, and end up with the usual result. It would make my life considerably easier if people listened or believed the manual now and then. ;)

Certain boards are designed with certain "objectives" in mind, and to fill certain niches. Were that not the case, you wouldn't have the PC's or the NB's or the Prizms. Everyone would just be playing with Crystal Focus boards. When I started that was all we had in the "custom" category. When I started, there were CF v2.1's. I have been around for each announcement of a new "class" of board, and know what the ideas and goals behind them were, etc. The "textbooks" are there for a reason. ;)