[TriEmbed] Starting to work with the LED strips from Adam - basic questions

[Adam Haile]

1) That should work. And is why I like the APA102 series.

2) Can't hurt. The AllPixel has the option of installing that resistor. But
on future revisions we are going to make it always installed. You don't
always need it but never hurts to have it.

3) Never used the Arduino Library. But I can pretty much guarantee that
FastLED is faster :) Also, if you use FastLED to write an animation,
switching out the type of LEDs you use is as simple as changing 1 line of
code. It's what the AllPixel uses under the hood. I love it.

4) Correct with 1 caveat. In most cases, the actual flex PCB power trace on
those strips is NOT designed to carry 10A for the full length. If you go
full white, the last pixels will "pink out" as Dan and I say... that is to
say that they don't get enough current and start to go pinkish (or off
completely). Solution is to power it from both ends. That's why those
strips have the JST connector with 4 (or 3 pins) but also have the 2 bare
power and ground wires. Just be sure that if you do this you power both
ends from the *same* power supply. You can power with 2 separate supplies
but you have to cut the 5V line somewhere in the middle while leaving
ground connected. I don't know the full explanation behind this, but
connecting 2 supplies in parallel like that can cause one or both to fail.
Not letting their power streams cross (There is no Dana, only Zuul)
prevents this... just be sure that ground stays connected so there's a
common all around. In general, my rules is 5A per 5m.

5) ha... yes, power from both ends. That's a must. 1000uF should be fine.
20AWG should be fine.

6) It's a standard "JST" 4-pin connector (3-pin for
NeoPixel/WS2812/WS2811). Basically, standard 0.1" pin spacing with a little
lever bit to prevent accidental disconnects. I buy them in bulk:
http://www.ebay.com/itm/2-100Pairs-4-Pin-JST-Male-Female-Connector-Cable-Wire-F-WS2801-LPD8806-RGB-Strip-/281454915853?pt=LH_DefaultDomain_0&var=&hash=item418805310d

Think you got it all... though, obviously, but sure not to reverse polarity
on the power. That would be bad :P


On Sun, Mar 1, 2015 at 9:38 PM, Charles McClelland <chip at mcclellands.org>
wrote:

> I think these questions will be answered by Adam in a heartbeat but, I am
> asking here in case anyone else will benefit.
>
> I opened the sealed bag for my 5m APA102 LED strips and started working
> out what I need to do to get started.  Given how much these strips cost and
> how long it takes to get a replacement, I thought it would be good to ask
> before I hooked up my 10A power supply and gave these things a whirl.  I
> have a list of questions and assumptions below, and would appreciate any
> corrections or answers from those brave souls who have gone before more
> into the technicolor future of programmable LEDs:
>
> 1) I will use a regular old 5V Arduino UNO since my APA102 LEDS are not as
> timing sensitive as the older types.
>
> 2) Question: Do I need to put a 330 ohm resistor in series with the two
> SPI wires to reduce the change of burning out the 1st LED. (as suggested
> here <https://learn.adafruit.com/adafruit-neopixel-uberguide/power>)
>
> 3) I will start with the Adafruit DotStart Library
> <https://learn.adafruit.com/adafruit-dotstar-leds> and graduate to Fast
> LED Library <http://fastled.io>  (of, course I will dump all this once my
> AllPixel arrives!!!).
>
> 4) I will use a 5V 10A switching power supply
> <http://www.amazon.com/gp/product/B0076UJZX0/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1> to
> run this monster (Adam’s previous post: "60mA per LED (20mA per color) at
> full white. So, for a 5m roll of 32 LEDs/meter that's 160 LEDs or a
> possible 9.6A draw")
>
> 5) I will put a 1000uF or greater electrolytic capacitor rated at 10V or
> more between the power and ground of the power supply and connect the power
> supply and Arduino grounds.  Ideally, I will connect the power at both ends
> of the strip.  For 10A, the “free air” rating
> <http://wiki.xtronics.com/index.php/Wire-Gauge_Ampacity> says I need 20
> gauge or thicker.
>
> 6) Question: I hate to cut those cool connectors off.  Any chance you know
> the part number I would need to buy the mate for the provided connectors?
>
> Am I missing anything or is there a better approach?  Don’t want to smoke
> these cool LEDs before I have a chance to play.  I have ambitions to try to
> put an Ambilight effect
> <http://blog.oscarliang.net/diy-tv-ambilight-arduino-processing-ozilight-1/> into
> my fiance’s family room someday (should be worth some points if done well).
>
> Thank you all and would love to hear what others will do with the $2000
> worth of LED’s
> <http://maniacallabs.com/2015/02/02/mail-bag-monday-8000-leds-edition/> Adam
> got for us.  Thank you Adam!
>
>
> Charles McClelland
> chip at mcclellands.org
> 919-624-5562
>
>
>
>
>
>
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