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Author Topic: PRIZM v5 Wiring Diagram with Neopixel Blade and Two 14650s  (Read 3527 times)

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Offline kornum

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PRIZM v5 Wiring Diagram with Neopixel Blade and Two 14650s
« on: July 05, 2017, 06:40:20 AM »
Hi All -

I am currently getting ready to build the Graflex that I'll keep. I've built a couple of 2.0 kits, am currently building a Roman's Graflex, and a bunch of other sabers (OWK, K4, MPP, and so on). But now, I'm starting to collect things for "my own" Graflex - the one to keep.

TGS Graflex replica, Solo's Hold blade holder, Martin Beyer chassis, Plecter Labs PRIZM v5, and a blade of Neopixel strips from Adafruit.
I'm just waiting for the TGS delivery now... ;)

I've got a few questions about the wiring, since I haven't wired up a Neopixel blade before. I've attached my wiring diagram below.
My first question is about resistors: what resistor should be used on the data channel? I'm thinking about using the 470 Ohm SMD 0603 resistors mentioned in the manual (they're tiny!), but I'm not sure how much tolerance it should have. Even with a regular 470 Ohm resistor, which I'm leaning towards to make the assembly easier, I'm still unsure of how much tolerance it will need.

Secondly, to be sure: the two 14650s in parallel to give 3.7 V 2200 mAh should be enough right?

Thanks!

Wiring Diagram:

Offline IceSaber

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Re: PRIZM v5 Wiring Diagram with Neopixel Blade and Two 14650s
« Reply #1 on: July 05, 2017, 07:24:04 AM »
I don't know much about that but im curious, why 7.4v? I thought the Nano could only handle 3.7.

Offline erv

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Re: PRIZM v5 Wiring Diagram with Neopixel Blade and Two 14650s
« Reply #2 on: July 05, 2017, 07:42:39 AM »
I don't know much about that but im curious, why 7.4v? I thought the Nano could only handle 3.7.

???
above doesn't show 7.4V but 3.7V

I've got a few questions about the wiring, since I haven't wired up a Neopixel blade before. I've attached my wiring diagram below.
My first question is about resistors: what resistor should be used on the data channel? I'm thinking about using the 470 Ohm SMD 0603 resistors mentioned in the manual (they're tiny!), but I'm not sure how much tolerance it should have. Even with a regular 470 Ohm resistor, which I'm leaning towards to make the assembly easier, I'm still unsure of how much tolerance it will need.

the data line has very little sensitivity regarding the resistor value. 330 to 470 ohm have been tested, and doubling this doesn't look to be an issue. 470 is just very standard, 5% resistors are not even the norm anymore (SMD's mostly come as 1% now)

your diagram looks correct to me, however keep in mind the "switch" is usually achieved by the Recharge port. If you plan to keep the switch, it should be able to accept like 6A minimum.

Offline kornum

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Re: PRIZM v5 Wiring Diagram with Neopixel Blade and Two 14650s
« Reply #3 on: July 05, 2017, 07:51:02 AM »
Thanks Erv!

That sounds perfect then. How easy are SMD resistors to solder onto the board for a novice?

Yeah, the switch just comes standard with Martin Beyer's chassis – I'm used to using a regular kill key in the recharge port, but c'est la vie.

IceSaber – wiring batteries in parallel will double the amps but not the voltage. It's only if I had wanted to wire them in series that it would have been 7.4 V.

Offline IceSaber

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Re: PRIZM v5 Wiring Diagram with Neopixel Blade and Two 14650s
« Reply #4 on: July 05, 2017, 07:54:03 AM »
oh there wired in parallel. Okay but why use 2 batteries when you can get a single one? Chassis restrictions?

Offline erv

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Re: PRIZM v5 Wiring Diagram with Neopixel Blade and Two 14650s
« Reply #5 on: July 05, 2017, 08:07:51 AM »
oh there wired in parallel. Okay but why use 2 batteries when you can get a single one? Chassis restrictions?

because no single 14650 would power a ledstrip

Offline profezzorn

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Re: PRIZM v5 Wiring Diagram with Neopixel Blade and Two 14650s
« Reply #6 on: July 05, 2017, 09:57:04 AM »
Secondly, to be sure: the two 14650s in parallel to give 3.7 V 2200 mAh should be enough right?

Probably not, and even if it was, it is still not a good idea...

First of all: You'll need batteries that can provide at least 6A (10A is better) of continuous current. I have not seen 14650 batteries that can provide enough current, but maybe they do exist?

However, if they do exist, just hooking them up in parallel is not a good idea. If the batteries are unprotected,  you can end up in a situation where one battery is charging the other at a very high speed which can damage the batteries and potentially cause a fire. If on the other hand the batteries are individually protected, it should be *safe*, but it still won't do what you want, because if the batteries are not evenly charged, one battery will try to charge the other which will trip the safety circuits of one or both of the batteries, and when that happens you won't have enough current to drive the LED strips.

What you really need to use batteries in parallel is a battery pack with circuits that protects and balances the cells together. However, I don't know if you can find such a battery pack that can provide enough current for the LED strips, which is why it's probably easier to just go with one 18650 cell.
« Last Edit: July 05, 2017, 10:02:05 AM by profezzorn »

Offline erv

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Re: PRIZM v5 Wiring Diagram with Neopixel Blade and Two 14650s
« Reply #7 on: July 05, 2017, 10:14:44 AM »
I powered my tron disc with 2x 14500 and 192 pixels.
Nobody should ever use un protected li-ion.
Parallel packs dont have a balancing circuit nor even a middle point circuit as they are single cell. The individual pcb of each battery provides cell protection during charge and discharge.

However the cells should be matched and pre balanced prior making the pack just like for a serial pack. A single cell parallel pack is self balancing during charging unless you really have a weaker element

Parallel packs are legions and simple to make. Lipo packs are made this way but they are more sensitive to care since they dont always have pcbs when made for super high drain

Offline Meatsweats

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Re: PRIZM v5 Wiring Diagram with Neopixel Blade and Two 14650s
« Reply #8 on: July 24, 2017, 11:26:04 AM »
Would someone be able to direct me to the correct SMD resistor to use. I'm not sure if I need thick or thin film and what wattage to use.

If I choose to just do an external resistor would this be ok? http://www.thecustomsabershop.com/390ohm-14w-resistor-P27.aspx

Thank you!

Offline jbkuma

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Re: PRIZM v5 Wiring Diagram with Neopixel Blade and Two 14650s
« Reply #9 on: July 24, 2017, 11:48:53 AM »
Would someone be able to direct me to the correct SMD resistor to use. I'm not sure if I need thick or thin film and what wattage to use.

If I choose to just do an external resistor would this be ok? http://www.thecustomsabershop.com/390ohm-14w-resistor-P27.aspx

Thank you!

Assuming this is for the data channel, just use the resistor in your blade connector with some heatshrink instead of running a wire.  You aren't concerned with the heat, so just heatshrink the whole thing to make life simple.

Offline erv

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Re: PRIZM v5 Wiring Diagram with Neopixel Blade and Two 14650s
« Reply #10 on: July 24, 2017, 10:38:17 PM »
Back to work today :-) ditton on the above, or use a 0603 smd resistor.

 

retrousse