10m 60led ws2812b capacitor?

Hello,
First of all I want to say I am quite new to Arduino and electronics. Therefore your answers may need to be dummy-proof :slight_smile:
I bought this ws2812b 3m light strip with 60leds/m, plus an arduino uno copy. I found out on the internet that these leds draw around 50mA when on full brightness. This added up to a total of around 9 amps, so i bought a dc5v 10a power supply and wired it together. Surprisingly it worked on first try and i used fastled’s code to get them lighting.
Now I want to step up and get a 10m strip to cover my entire room. I read somewhere that you need a capacitor, but some say it isn’t necessary. I didn’t use a capacitor on my first strip either.
Now would you recommend a capacitor, and if, which one?
Also is it correct that if i buy a 60a power supply i can wire the 2 5m strips together and power them from one end? Could i also add the 3m strip to get a total of 13m?
Sorry if any of these questions are obvious, as mentioned above i’m just getting into arduino.
If i need anything else or doing anything wrong, please let me know.
Thanks in advance:-).
William

Actually, full brightness is specified as 55 mA per LED.

The UNO is not the best for projects, a Nano is more practical. They are functionally the same for most purposes, just the form factor. In either case, the limited RAM means you can control up to something like 500 to 600 LEDs with very simple patterns, but much less if hte program is more complex. People have had trouble controlling 300.

So you propose to have 13 m of 60 LEDs per metre, that would be 780 LEDs. That is not going to work! :astonished: Your single 3 m or 5 m will be OK though.

william1305:
Now I want to step up and get a 10m strip to cover my entire room. I read somewhere that you need a capacitor, but some say it isn’t necessary. I didn’t use a capacitor on my first strip either.
Now would you recommend a capacitor, and if, which one?

Whether the 470 µF or 1 mF (that is, 1000 µF) capacitor at the start (data input) of the first strip is critical rather depends on the distance between the power supply and the LED strip. It is indeed, advisable like the 330 Ohm resistor in series with the data input at the start of the first strip But you have other problems.

william1305:
Also is it correct that if I buy a 60a power supply i can wire the 2 5m strips together and power them from one end?

No!

william1305:
Could I also add the 3m strip to get a total of 13m?

Limited by the UNO.

The foils on the strip are capable of carrying only a limited amount of current. They are just as likely to burn out like a fuse at somewhere around 10 Amps. If you propose to illuminate anything near full brightness white, you need to inject power (that is, 5 V and ground of course) into the strip every 60 (3.5 Amps) LEDs or so from a reasonably heavy power cable ( 1 mm2 at least).

And remember that all supply and return wires - 5 V and ground as well as data and ground - must be kept together as a bundle wherever they run; there must be no open loops in the wiring. :grinning:

There are ways to get an Uno/Nano to run this many leds. They all involve splitting the total strip into shorter lengths, each length short enough for the Ardino to deal with. For a total of 780 leds, you should get away with splitting that into 2 strips of 390 leds.

The simpler method involves connecting the data inputs of both strips to the same arduino pin (probably using a resistor for each strip). With this method, the two strips will always show identical colours/patterns. Depending on the exact patterns you want, this may be perfectly acceptable, and simple in coding terms, because the Arduino thinks only 390 leds are conected.

The more complex method involves connecting the 2 strips to separate arduino pins (each with its own resistor). Now, the two strips can be completely independant, showing different colours/patterns. This method involves sharing the same memory buffer between the two strips. First, the pattern for the first strip is assembled in the memory buffer, then sent out to the first strip. Then the buffer is cleared and the pattern for the second strip is assembled and sent out, and the buffer is cleared again ready for the next update of the first strip. This is no slower than it would be if the Arduino had sufficient memory for both strips to have dedicated buffers. However, some animation patterns you may find on-line, including some of the FastLED examples, will not work with this shared buffer. This is because they rely on the previous pattern still being present in the buffer, and updating it. That won't be the case if the buffer is shared, because it gets cleared each time.