Addressable RGB LEDs without going nuts

[NivagSwerdna]

I really like NeoPixel (WS2812b et al) and I have a couple of home projects with my kids that use them but the wiring is driving me nuts!

So for example I have a panel with 27 Neopixels.... each pixel has +,-, DataIn and Data Out.  The Neopixels I bought come on a mini PCB and I have been soldering wires to these one at a time and slowly losing my will to go on... particularly as I would eventually like quite a few of these panels.

So... I am obviously doing this WRONG!

The LEDs I have don't look PCB friendly... all the contacts are on the bottom and if I tried to reflow these wouldn't all the bits on the top start to float around.

Please can someone suggest an alternative?  I think I am happy to pay the PCB cost (even though it is quite big) just to save me the time but I would need PCB friendly neopixels.

I DO need each pixel to be individually addressable but no other constraints... I'm not necessarily bound to WS2812.

e.g Can you buy the components separately.... do you need a C and R at each like the mini-board?

(I tend to buy my stuff via Farnell... but I never seem to see WS2812 et al there??)

Thanks in advance

[Ian.M]

Each Neopixel needs the 0.1uF decoupling cap but only the first in the chain needs the resistor.
You can buy 'bare' Neopixels in either SMD or through hole packages.  See https://cdn-learn.adafruit.com/downloads/pdf/adafruit-neopixel-uberguide.pdf

[NivagSwerdna]

I checked EBAY and Farnell....

It looks like buying the chips on the mini circular boards might be the cheapest even if I need to have the additional hassle of flowing them off (and I do have a track record of distorting/melting LEDs on reflow)

Do you think it actually would be feasible to SMD the circular boards... solder paste and heat?

[mikeselectricstuff]

I checked EBAY and Farnell....

It looks like buying the chips on the mini circular boards might be the cheapest even if I need to have the additional hassle of flowing them off (and I do have a track record of distorting/melting LEDs on reflow)

Do you think it actually would be feasible to SMD the circular boards... solder paste and heat?

Why would you do that rather than just using the LEDs on their own?

pretty sure there are a few options for pre-wired strings - try Aliexpress

[NivagSwerdna]

I am fussy about the geometry so pre-made won't work.

I am yet to find a source of cheap vanilla/unsoldered 5050 addressable LEDs.... the mini-board type I have are £5 for 50 on the slow boat.

[CJay]

First ideas off the top of my head:

Plated through hole double sided board where the PTH holes are large enough to get the tip of an iron into?

The holes align with the pads on the Neopixel board, flux it up and fill the hole with solder while clamping the neopixel to the other side?

Better would be a slot but I'm not sure if you can get the edge of a slot plated?

Another alternative might be to solder header pins to the neopixel to convert them to a 'DIL' package and use either a PCB or prewired sockets.

*edit* attached a pic of one of my prototyping Neopixels, would need the header pins to be perpendicular for your needs but you get the idea...

[janoc]

I am fussy about the geometry so pre-made won't work.

I am yet to find a source of cheap vanilla/unsoldered 5050 addressable LEDs.... the mini-board type I have are £5 for 50 on the slow boat.

You aren't looking in the right places. AliExpress is full of these:

https://www.aliexpress.com/item/10-1000pcs-SK6812-4pins-5050-SMD-similar-with-WS2812B-Individually-Addressable-Digital-RGB-Full-Color-LED/32550663121.html

I have ordered them from the above seller and no problem whatsoever.  Actually those LEDs use a slightly different driver that is a local Chinese improved (!) version of WS2812B, but are compatible.

You can also get self-adhesive strips, through-hole LEDs with this driver and what not, just search for WS2812b on AliExpress. Do not search for "Neopixel" - that is a business name that only Adafruit (and the "maker" community) uses, you won't find much under that name.

[NivagSwerdna]

You aren't looking in the right places. AliExpress is full of these:

https://www.aliexpress.com/item/10-1000pcs-SK6812-4pins-5050-SMD-similar-with-WS2812B-Individually-Addressable-Digital-RGB-Full-Color-LED/32550663121.html

Thanks for the SK6812 suggestion.  There seem to be much more options there.  Sorry our posts crossed.

[Ian.M]

One thing to be cautious about - I believe there have been some reports of high defect rates for the Chinese WS2812B clones.   You may have to either do a lot of rework or set up to test individual ones before assembly.

[NivagSwerdna]

One thing to be cautious about - I believe there have been some reports of high defect rates for the Chinese WS2812B clones.   You may have to either do a lot of rework or set up to test individual ones before assembly.

Fair point.  Since these are for home use only, i.e. not production, that should be OK but a pre-assembly test makes a lot of sense.

[janoc]

One thing to be cautious about - I believe there have been some reports of high defect rates for the Chinese WS2812B clones.   You may have to either do a lot of rework or set up to test individual ones before assembly.

Haven't heard about that. It could have well been simply a dodgy seller selling dodgy parts - e.g. rejects. However, it is possible to find also the original WS2812Bs there.

OTOH, if you don't want to risk AliExpress, you can buy from Digikey:
https://www.digikey.fr/product-detail/fr/1655/1528-1104-ND/5154679?curr=eur&WT.z_cid=ref_octopart_dkc_buynow&site=us

However, even Digikey states that:
"LED RGB WS2812 OR SK6812" - those are the Adafruit parts and Adafruit is taking them from China.

[endevor100]

Could you make premade addressable strips work for your panel geometry? They would be the easiest to wire up. There are many options if you search "individually addressable led strip" and the first one off the google pile I liked is this product: https://www.amazon.com/240pixels-programmable-Individually-addressable-Waterproof/dp/B00K7UHPEC

[NivagSwerdna]

Could you make premade addressable strips work for your panel geometry?

No.  I have a very custom design using laser cut geometry, every millimeter matters for the aesthetics.
I spent the afternoon wiring up my first panel and it looks good.  For any quantity I would have to consider a new approach... a single custom PCB would be very expensive (although I could use the other side for the microcontroller etc) since with my current design it is 271.5mm x 63mm... I could perhaps have modules... groups of six or nine. (I find anything greater than 100mm x 100mm gets £££)
In any case this version is a prototype so my final dimensions might change.
I also found http://pi-plates.com/the-problem-with-neopixels/ which has some comments about the sensitivity of the internal parts to agressive soldering.

[ebclr]

This is the wiring you need to do


And here case you wana use Arduino

[hamster_nz]

I found them to be very sensitive to handling while breadboarding, with the first of the chain blowing. Maybe ESD, maybe dodgy +5V conmection allowing DI to get much higher than Vdd.

[Ian.M]

I found them to be very sensitive to handling while breadboarding, with the first of the chain blowing. Maybe ESD, maybe dodgy +5V conmection allowing DI to get much higher than Vdd.

Adafruit recommends a series resistor of between 300 and 500 Ohms in the data line, adjacent to the first LED to damp ringing, and provide such a resistor on most of their PCB mounted Neopixel products.   They also recommend a very large bulk decoupling cap across +5V and ground, to damp transients.

I suspect they suffer from the same problem as many LDO regulators - the supply lead inductance can ring with the ceramic decoupling cap and over-voltage the chip if the power-up rise rate isn't controlled.

[chris_leyson]

Adafruit recommends a series resistor of between 300 and 500 Ohms in the data line

Last time I used a string of WS2812Bs I needed 330 ohm series resistor otherwise they just wouldn't work. I should have had a close look with a scope.

[Buriedcode]

Like others I'll just ad comments.

- There are TH addressable 5mm RGB LED's available.  This may or may not be preferable to the SMT type.

- I'm sure I have seen large (120x450mm) stripboard prototype boards on ebay.  You can solder the 6-pin 5050 or the 4-pin 5050 Addressable LED's directly to these, but will still require soldering an awful lot of jumpers on the back to hook the DOUT to DIN of the next one for either the 4-pin or 6-pin.  For long runs you might want to use more than one strip for the power rail and ground, but the layout means its very easy to add decoupling caps distributed along the lines.   If you insist on having a custom laysout for the LED's, this is probably the best combination of cheapness and convenience, whilst keeping functionality.

- As has been suggested, why not LED strips?  They generally have decoupling caps on the strip, and the cheapest have low densities, ~30 LED's per metre which is ~1 5/16" spacing. Looks similar to what you have on those boards.  They have self adhesive, easy-to-use connectors, and you can break them up into strips of only 8 LED's, and have 4 of those stuck to your MDF blocks.  You would only have to wire connectors between strips (wiring three 4-wire connectors, rather than 4x8 =32).   They are also dirt cheap, available everywhere, and have more options (RGBW, low profile - SK6812, waterproof etc..).

- 'Neopixel' is the brand for Adafruit Addressable LED's.  You mentioned you get 50 for $5 which is a great price.  Adafruit are often much more expensive.  It seems like getting LED's on individual boards might be cheap, but as you found out is making life *more* difficult in terms of wiring. 


Conclusion:  Seriously, get some WS2812B strips. For ~ $20 you can get a few metres, which means you'll have lots spare should any LED's die - and replacing the strips will be easy if you use the snap-in connectors. It will greatly reduce the wiring time whilst still allowing the pattern you have in that pic, should be more reliable (less fannying about worrying about decoupling) and let you spend more time on other parts of the project. The cons? You're not doing something entire from scratch. but if that was the point of the project, then I'm sure you would be happy to do all that wiring.

[tooki]

Why not just get the same modules you already have, but pre-wired, like this? https://www.aliexpress.com/item/50-x-SK6812-Pre-soldered-Addressable-Individully-RGBW-led-string-Neutral-white-WWA-pixel-module-light/32749443892.html

[Flenser]

They do make clip-on connectors for the flexlble RGB LED strips:
http://www.ebay.com.au/itm/Weldless-Clipon-Coupler-Connectors-2pin-4pin-RGB-for-3528-5050-LED-Strip-Lights-/282214429792?var=&hash=item41b54a7460:m:myzXT4lOEk26hhxx9MMyHxg
http://www.ebay.com.au/itm/2pcs-4pin-LED-Strip-connectors-5050-RGB-10mm-PCB-board-wire-No-Soldering-/162535648487?hash=item25d7e12ce7:g:qQsAAOSwH09ZLnJ7http://www.ebay.com.au/itm/5x-10mm-4-pin-Solderless-Clip-on-Coupler-Connector-for-5050-RGB-LED-Strip-Light-/292139734832?hash=item4404e29730:g:ZDEAAOSwr7ZW6KDP
http://www.ebay.com.au/itm/L-Shape-RGB-Led-Strip-Light-Connector-Ribbon-String-Corner-Female-Adapter-/222533922570?hash=item33d00e2f0a:g:8xIAAOSwPh5ZMvWP
http://www.ebay.com.au/itm/No-soldering-3528-8mm-5050-10mm-T-L-X-Shape-Adapters-LED-Strip-Connectors-RGB-FT-/131779786020?var=&hash=item1eaeaff524:m:mEC4EsWBkpMC85E4Jhf8qwA

and plug-in connectors:
http://www.ebay.com.au/itm/L-Shape-RGB-Led-Strip-Light-Connector-Ribbon-String-Corner-Female-Adapter-/222533922570?hash=item33d00e2f0a:g:8xIAAOSwPh5ZMvWP