Building DIY LED strips for fun | Hacker News Reader

Building DIY LED strips for fun

a.wholelottanothing.org

100 pointsMindGods33 comments

If you came here hoping for good resources on how to set up and control LED strips, angry that the article linked was bad and devoid of any good details, here are some useful resources.

#1: AdaFruit loves you and has a guide: https://learn.adafruit.com/adafruit-neopixel-uberguide

#2: Andreas Speiss has a phenomenal youtube channel that offers a lot of solid tips and tricks for new makers looking to avoid common pitfalls: https://www.youtube.com/watch?v=IIl5nDjfkjY

#3: GreatScott! (another great youtuber) has a really fun article on what I'd label a very "intermediate" LED project to get a sense of how to put everything together to make a unique object that is not simply a matrix and a lot of software: https://www.youtube.com/watch?v=tXfMg8y1Fs4

Good luck, and one last tip: remember to be careful that your microcontroller may be fried by the voltage your LED strips needs. It may seem that there is an obvious solution to that which is, "Just use 2 power supplies" but with 3-wire LED strips group loops can exist and ruin your ability to control the strip. Don't despair, search for "buck converter board" and then look up how to tune it. You'll get a system efficient enough that you can drop 12v to 3.3v and it won't drain your battery or overhead your enclosure. Linear regulators are not your friend, they're usually cheaper specialist tools for folks who care about radios.

As for voltage difference between controller and lights, you can sacrifice the first led and power it at 3.3v and power the remaining ones from a second power supply. The first led will be a little dimmer than he rest but this setup has been very stable in my tests.

At that point I'd just grab a heavy resistor of the appropriate value and wire the controller down rather than accept a dead pixel in my line.

Usually this is a problem for 12V LED lines with 3V3 microcontroller like the ESP32.

How does that work? Do I understand correctly that you connect the first led to a esp32 (+3V, onewire, GND) and then connect +12V and GND to the second led?

I wonder why it wouldn’t work if you connect +12V on the first led?

The LEDs in the article are WS2812B LEDs that operate at 5v rather than 12v. 5v is a slightly more "normal" LED voltage, 12v strips are usually going little tricks like have 3 or LEDs in series and using that to get the required 12v drop.

With the WS2812B you're issue is that they operate on 5v logic for communications. 3v logic from a chip can _just about_ communicate with 5v devices. But you can't send the signal very far before the voltage drop stops communication. The cheat here is to use a single WS2812B LED as logic voltage converter. You put a resistor in line so it's operating at ~4v, give it a 3v logic signal it can understand, and it'll then talk down stream using ~4v logic, which you can then pump into normal 5v LEDs.

You can find detail of this little trick on hackaday[1]. But it's specific to WS2812B type LEDs that are really microcontrollers that happen to also put out light, rather than traditional dumb LEDs that have no smarts.

[1] https://hackaday.com/2017/01/20/cheating-at-5v-ws2812-contro...

IME, you can use 3.3V logic with 5V WS2812B/SK6812 strips, no trouble.

Each LED reforms the signal before sending it to the next LED in the chain, so voltage dropping over distance shouldn't a huge issue for the logic line unless the strip is very far away from the controller.

And the datasheet almost agrees with my experience; the "high" voltage threshold is listed as 0.7×VDD, and 0.7×5=3.5V. That's a bit over 3.3V, but I haven't had any issues across several projects. Maybe it's because many USB supplies provide a little over 5V to account for droop? Maybe the datasheet is slightly pessimistic? Maybe 0.7 really means 2/3? Whatever the reason, it simplifies the wiring for small displays.

Here's my favorite reference for the single-wire protocol that these LEDs use, since everyone seems to be chiming in with one:

https://wp.josh.com/2014/05/13/ws2812-neopixels-are-not-so-f...

I think maybe folks got the model number confused. There are strips where the entire signal is passed verbatim without being reformed to every package on the line, but everyone stopped using them because they're awful.

In my experience, slow microprocessors are WAY more tricky to deal with than a 3V3 logic voltage for these strips; and often lead to crazy hacks. I'd way rather just put a modestly powerful resistor or a buck converter in my project than deal with trashy old Atmel chips, given how absurdly cheap ESP32 and ARM M7 packages are.

This is a nice, interesting, useful article, but the title is garbage.

Step 1: Buy some WS2812B strips.

You're not building the strips. You're building the control infrastructure.

I believe the word you're searching for here is "clickbait."

Controlling LED strips is not a boring project and it's a wonderful entry into the hobby since it often works with very safe voltages and is happy with cheap components.

But this article is clickbait, and it's probably the most detail-free article imaginable on the subject.

> works with very safe voltage

True for constant voltage, resistor limited current ones only. With constant current LED drivers, the voltage is approx 3V per LED. So it adds nicely to unsafe levels, albeit DC.

Another note is the power supplies can be quite unsafe too - esp. the cheap off-brand ones.

Panels and strips using more than 24V are extremely rare, with 12V being common and 5V existing for the hobbyist crowd. I've never seen a 24V rig for hobbyist uses (although some Ikea strips run there).

You don't wire them in serial anyways. In general if you care about blocks of LEDs at all you don't wire them in serial.

For some reason I also thought this was about making the strips for fun. But this has nothing to do with making, it's just assembling someone else's strips...

I was just curious to see how one would go about making strips. Order a bunch of wires and hand solder some SMD LEDs? Get a FFC made by a random PCB manufacturer and solder LEDs on those? Make some sort of mould and use one of those odd silver glue connections to an existing wire strip? Order a bare strip and use solder paste and a heat gun or hot air soldering station to solder them on and then dip the whole strip in transparent elastic resin?

Instead of having some curiosity itch scratched it just makes it worse.

Agreed. Somewhat interesting article, terrible title.

Something like "Custom Lighting With Controllable LED Strips" would be better.

I get that you both thought maybe I was soldering my own strips raw but the DIY in the title is about setting up your own strips, not just buying a bunch of LIFX or Hue strips.

which is "building WITH LED strips". I once "built" a LED-matrix display from strips, because it was a demo project and money for HW was scarce (and time to short to look into fabrication for a non-EE-person; also brightness maxes out at 1000cd/m² last I checked) - I seriously came there for some info how you created your own, cheap DIY high-density setup for the WS-LEDs (cooling becomes also a problem eventually for high brightness, so I was looking forward to a solution to this problem). Instead I got the blog equivalent of a YT-video: how to decorate your room in 5 easy steps.

BTW: You actually did do nothing more than buying a bunch of strips, I don't see a big technical difference between hue and chinese strips + a chinese hue-bridge except for the soldering (but afaik they also offer connectors for solderless application...). So you might change the title to: "setting up a chineses hue replacement for cheap with soldering" (though I would expect pictures of your soldering then...

This article isn't for you. It was written for people that have never soldered in their lives or built anything from parts.

Hey, keep it up. I'd be very embarrassed if any of my blog posts ended up on HN, too.

You'll get there! :)

LEDs get a lot of attention from people without any kind of training with electronics, but they aren't as simple as people think - LEDs consume a lot of power. If someone isn't careful and doesn't know what they are doing, it's very easy for them to create a fire hazard.

https://hackaday.com/2018/01/29/the-engineering-case-for-fus...

good to see that! I (physics grad) was eyed very skeptically by a crowd of CS and architecture (like in houses) people, when I started buying fuses and caring about fire-safety (all the people were much like: oh light, wow (whilst I was: power, hot)

It's also very easy to create crappy lighting conditions because people think of light to be just 'light' which it isn't.

This one on "self organizing LEDs" was fun and motivating:

https://news.ycombinator.com/item?id=23741036

Video: https://youtu.be/Ueim2Ko8VWo

Pretty simple to do this honestly, it's been done many times before. There are phone apps that do this that have been around for a while. After all it's just assigning an x/y value to a position that a color was detected at.

That looks really slick. Nice job!

These sorts of projects can be a lot of fun. I did the same sort of things a couple of years ago on my deck.

I had a rpi and Arduino in the loop cause that’s what I had lying around, the ESP solution sounds much simpler.

Then we moved a couple months later...

https://imgur.com/gallery/E4lbU

Adafruit is an amazing source, their NeoPixel ecosystem is exceptional. They also offer an RGB NeoPixel strip variant with modules that ALSO have a dedicated "warm" or "cold" white LED module. This is great in case you want to actually use your LED's as non color LED's for some time.

I found this to be a rabbit hole. e.g. Ideally you want 24V not the 12V most of the cheap stuff is. And then you really want one that has warm white LED instead of just RGB'ing the white.

...and pretty soon you're looking at real money

I actually went 5V and it’s fine. I forgot to stress that in the post but I’ll update it.

5V is extremely bad from efficiency point of view. The voltage drop over an LED is ~3V, that leaves 2V to be sent through the current limiting resistor (dissipated as heat). There could be only a single LED (no series).

These strips have a chip and individual control for each RGB LED that work on 6V max, so "higher voltage would be better" doesn't really make sense for them (unlike strips where all LEDs in the strip are driven the same, without individual control).

Obviously, I didn't mean addressable RGB LEDs, just regular LED (white) strips that can be cut (in the context of the grandparent's comment)

I considered using 24V for my living room lighting, but availability is an issue. The much more common 12V works fine as long as you consider the wire gauge you need to prevent the voltage from dropping too much.

For example, if you use RGBWW strips (i.e., four channels; RGB plus warm-white, as you rightly recommend), you could have one -12V lead shared with a thickness of 4mm², and four separate 12V leads at 1.5mm². At around 4.2m distance (at the farthest) I measured an acceptable voltage drop of 3.9% for 405 SMD5050 RGBWW LEDs.

But yeah, you do need to consider the wire gauge of your cabling, depending on the number of LEDs driven.

Why 24V? What does it improve?

Power is proportional to the voltage squared (P = V * V /R), so the power supplies need less current -- cheaper, more reliable - less heat, less voltage drop.

The same holds true for the power supply in NA vs most of the world (save Japan). 110V vs 230V - much less copper needed for conductors. motor windings, etc.

Flip note: the better option is using constant current drivers, for higher efficiency (they might have unsafe voltages, though)

More light output mainly. If you have a look at the philips hue lightstrips you'll see it there too. The 24v pumps out way more lumens. i.e. Useful levels of light not just decorations.

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