Noob questions about wiring

Hi there,

I am planning to make a wled controller for my 5v WS2812B led strip and can’t seem to find the right answers. Hope you experts can help me out :smile:

I am reading and searching the web for some weeks now to find a wiring tutorial where they use the level shifter, resistor, capacitor and fuse. But i can not seem to find the right guide. I watched the video tutorial from Dr Zzs and Bitbastelei/Adlerweb that are posted on Tutorials - WLED Project but they do not use all the items mentioned above.

So my question is; Do i need to use a level shifter, resistor, capacitor and fuse to make it as safe as possible and if so does anyone know where to find the right guide for this?

I also found a wiring guide from Adafruit where a Arduino Uno is used. Is this the capacitor and resistor that also can be used for the NodeMCU or is there a better board that i can use?

Safety items:
Proper power wire size - not explicitly on your list but goes hand in hand with Fuse size and voltage drops.
Fuses - once you know how much current (that’s the number of Amps) you need in your wire(s) to keep from having too much voltage drop, you put in a fuse to allow ~20% more than that before blowing. Let’s you handle surges safely, but will blow in case of a short.

Non safety, but performance items:
Level Shifter, resistor, capacitor: all these items are concerned with the Data going to your strip(s).
You may or may not need some or all to get a reliable display. If you get it wrong things may flicker or display wrong, but it won’t be unsafe (as long as you have dealt with power properly).

For me, I test drive my setup with short (< 30cm) distances from the MCU to strip first but hookup proper power. I will hookup directly without level shifter, resistor or capacitor. I try and test what I can in terms of max power and brightness, measuring the actual current drawn by a subset of say, 100 LED’s so I can calculate the expected maximum current for the whole strip.

I’ll try a few effects to see how it looks and then increase the data distance from the MCU to strip up to 5m and see how reliable it looks with effects. For data distances beyond 5m, I almost exclusively change over to differential TxRx pairs. They are cheap (< $3/pair) guaranteed reliable up to 100m and eliminate most if not all the issues with trying to make longer data runs work.

This is all my $.02, but my experience has been - make sure your power is clean and adequate for the entire length of the strip and deal with data as a separate entity.

If you post your expected size/type of strip, power supply, and the MCU you hope to use, we can probably point you on the right path with more suggestions.

Thank you very much for your quick reply!

I have made a quick diagram to show the setup i am trying to build.

  • The power supply is fused (is this the fuse we are talking about?)
  • How can i calculate the wire size from psu to led strip ( lenght=3,5 at max )
  • Led strip is the WS2812b
  • Amp calculation if i am right: 288 leds x 0,06a = 17,28A

I do not know if and where i should place a level shifter?

I don’t know what this is and it seems a bit to advanced for me.

I hope this helps in what i am trying to build.

Also, that resistor is much too big.

Spend some time here…
https://kno.wled.ge/

Your diagram looks pretty well thought out in general, you’re on the right track.

On the fusing issue, depending on the risks involved with installation/placement some would recommend a separate 10A fuse on the +5V before it goes to the 2 injection points on each strip. That way if something shorts in a strip, the fuse blows before the wires melt.

Now that you have some idea of the worst case current requirements for each strip, you can work out the potential voltage drop issues. You can use one of the drop calculator’s in the tutorial section of https://kno.wled.ge (@tonyno’s right, this a great resource), I like:Voltage Drop Calculator. Set it up for DC, 5V Plugin the max current you’ll need for one side and the actual length of wire from the PS to the injection point. I’d start with 18AWG wire and work up if necessary. This is about picking the right size wire for the distance you want to carry your needed current.

As far as data lines, you’ve drawn this up where the two strips are fed from a single data source.
Each strip will display the identical colours as sent from the MCU, if that’s all you need this will work out.
You could also split the data so you have 2 independent lines from 2 GPIO’s on the MCU. That gives you the flexibility of duplicating the colours in WLED or running things separately.

The need for a resistor will be highly dependent on the length and location of the data wires. As @tonyno mentioned, 470 Ohms is very high start at no more than 220 Ohms and work down. I personally don’t use them at all. A level shifter may or may not be needed to bring the MCU output up from 3.3V to 5V levels. The capacitor is ok, although I find them unneeded if you have good power connections.

My mention of TxRx pairs was discussed in: Personal project for my backyard... which way to choose? - #5 by divsys and Long Data Wire + ESP8266 + Level Shifter - #7 by divsys. They come into play when you have a long run and don’t want to mess with trying to force TTL data to play nice. IMO TxRx pairs are the easiest solution to long run issues.

Have fun looks like you’re well on youur way :grin:

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Thanks a lot for the great help!

I am going to read some more articles on https://kno.wled.ge and work on the tips you gave me.

Thanks again!

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