Little help with a WS2812B strip and Arduino UNO

Other Hardware General Electronics
1

Hi i just bought an led strip, this one to be exact: https://amzn.to/2ZIGWfx 150 divided in 3 sections, from 0 to 36, to 37 to 92 and 93 to 149, according to the documentation from the neopixel website and some videos online i dont need to inyect power yet, im about the 5m (16.4FT) mark.

Now the power supply i got is 5V, 10A, again according to the neopixel site and the seller this strip draws about 7 to 9 amps at full white bright, so it should be fine, but here is the problem, the leds got that decoloring from lack of power like in the 45th led at full white, so i don't know if im doing something wrong or im failing my math or theres something bad.

This my current wiring: Imgur: The magic of the Internet Just without the 330 ohm resistor and also power the arduino with the USB from my PC, that the onli difference.

Im a beginner with this so if you see something wrong im sorry, but can i get a little help with this? I saw some other diagrams without the 5v cable to de arduino i suspect that may be but i dont want to blow up something if i remove that cable without knowing.

PD: I powered once the arduino first without the power suply plugged in by mistake and all the leds turned on with the decoloration.

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ryuushinno:
according to the documentation from the neopixel website and some videos online i dont need to inyect power yet, im about the 5m (16.4FT) mark.

What Neopixel site, and what videos.

Red shift is a sign of volt drop. You can measure that with a DMM (voltmeter).
45 LEDS at full white is about 45*0.06= 2.7Amp, but low density (30/m) is also a factor (copper/strip length).
And so is the wiring (size, length) between supply and strip, which you didn't tell.
Better inject power at three or four places in the strip.
Leo..

3

I meat adafruit sorry

The wiring between strips is not much, i just 30cm of wire between cuts, so it suposed not to have voltage drop till the lastest pixels, about 140 and 149 ones, that would be kinda acceptable for the moment, but thats not the case,

This is the type of wire i used for the whole ting

But there's a thing if i put only some of the lastest pixels at full brightness, they do go full without the drop, so doesn't that means that the strips are getting power from the arduino instead of the power supply, which they should?

4

But there's a thing if i put only some of the lastest pixels at full brightness, they do go full without the drop

If you only draw a few milliamps then you don't get much voltage drop across the wire resistance (Ohm's Law).

so doesn't that means that the strips are getting power from the arduino instead of the power supply, which they should?

If you wire it correctly there's no way the LED strip can get power from (or through) the Arduino.

5

DVDdoug:
If you only draw a few milliamps then you don't get much voltage drop across the wire resistance (Ohm's Law).
If you wire it correctly there's no way the LED strip can get power from (or through) the Arduino.

Oh i see i get it thanks for that one!!, one thing im not getting, if i unplug the 5V wire from the arduino, should the led strip turn on if there are powered by the power supply? or it needs to be plugged in even when the power suppy is present?

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Never plug and unplug power or anything else when part of the circuit is powered up. That is the way to destroy things.

You should connect the Arduino’s 5V to the same power line as you power your LEDs and then turn on that power supply.

If you want to program the Arduino then turn off the power supply, disconnect the 5V connection to the Arduino and then plug in the USB. You can leave the power supplies ground and Arduino’s connected.

Initial flashing of the LEDs on power up mean nothing, some do it some don’t.

To stop the yellowing at the ends apply the power and ground to both ends of the strip. I hope you have the resistor and capacitor attached like the AdaFruit site says.

7

Grumpy_Mike:
Never plug and unplug power or anything else when part of the circuit is powered up. That is the way to destroy things.

You should connect the Arduino’s 5V to the same power line as you power your LEDs and then turn on that power supply.

If you want to program the Arduino then turn off the power supply, disconnect the 5V connection to the Arduino and then plug in the USB. You can leave the power supplies ground and Arduino’s connected.

Initial flashing of the LEDs on power up mean nothing, some do it some don’t.

To stop the yellowing at the ends apply the power and ground to both ends of the strip. I hope you have the resistor and capacitor attached like the AdaFruit site says.

Thanks i think i have a bad connection somewhere i check and definitively leds are being powered by the arduino, im gong to check all with a bread board, and yes i do have the capacitor and resistor.

Im just need to clarify something, i look up the voltage for the VIN Pin on the arduino uno, in the oficial site, it says the recomended voltage for te VIN Pin is between 7V and 12V, but my power supply is 5V because of the Led Strip, is there any risk of damage the board if power it with 5V as i have saw on some schematics?

And thank you very much to all, i learned a lot!

8

ryuushinno:
This is the type of wire i used for the whole ting
Ribbon Cable - 6 Wire (15ft) - CRCibernética

That's signal wire, not power wire.
It can carry 1.5A at the most. and has a resistance of about 0.2ohm/m, possibly causing a massive volt drop.
How long, and how is it wired.

I hope you're NOT powering the LED strip THROUGH the Arduino.
Leo..

9

look up the voltage for the VIN Pin on the arduino uno, in the oficial site, it says the recomended voltage for te VIN Pin is between 7V and 12V, but my power supply is 5V because of the Led Strip, is there any risk of damage the board if power it with 5V as i have saw on some schematics?

You have a 5V power supply so you must connect that to the 5V pin on the Arduino to power it. In your case do not use the Vin pin as that will result in a lower voltage powering the Arduino.
Vin is only useful when your supply is over 7.5V and you are not powering very much through the Arduino. The onboard regulator that makes the Vin voltage into 5V will quickly get hot if the Arduino has more than a few LEDs or sensors. At 12V input then you can power nothing else but the Arduino. So you do not use it with your 5V supply.

You only see 5V being fed into the Vin socket in schematics drawn by people who do not know what they are doing. There a lot of idiots out there.

10

Wawa:
That's signal wire, not power wire.
It can carry 1.5A at the most. and has a resistance of about 0.2ohm/m, possibly causing a massive volt drop.
How long, and how is it wired.

I hope you're NOT powering the LED strip THROUGH the Arduino.
Leo..

Only about some days, i haven't done much since because os this thing, so then i will change all the ground and volt wires with more proper ones, also i thought i was powering with the power supply but aparently not, im going to rewire everything, thanks!

Grumpy_Mike:
You have a 5V power supply so you must connect that to the 5V pin on the Arduino to power it. In your case do not use the Vin pin as that will result in a lower voltage powering the Arduino.
Vin is only useful when your supply is over 7.5V and you are not powering very much through the Arduino. The onboard regulator that makes the Vin voltage into 5V will quickly get hot if the Arduino has more than a few LEDs or sensors. At 12V input then you can power nothing else but the Arduino. So you do not use it with your 5V supply.

You only see 5V being fed into the Vin socket in schematics drawn by people who do not know what they are doing. There a lot of idiots out there.

Okay ill keep that in mind thank you so much!!

11

ryuushinno:
Im just need to clarify something, i look up the voltage for the VIN Pin on the arduino uno, in the oficial site, it says the recomended voltage for te VIN Pin is between 7V and 12V, but my power supply is 5V because of the Led Strip, is there any risk of damage the board if power it with 5V as i have saw on some schematics?

This is my pet hate. :astonished:

Please, please, please forget that the "Vin" pin and the "barrel jack" even exist. :roll_eyes:

A very real danger is that the obsolete tutorials on the Arduino site and others misleadingly imply that the largely ornamental "barrel jack" and "Vin" connections to the on-board regulator allow a usable source of 5 V power. This is absolutely not the case. It is essentially only for demonstration use of the bare board back in the "old days", the very beginning of the Arduino project when "9V" transformer-rectifier-capacitor power packs were common and this was a practical way to power a lone Arduino board for initial demonstration purposes. And even then it was limited because an unloaded 9 V transformer-rectifier-capacitor supply would generally provide over 12 V which the regulator could barely handle.

If you are dealing with this, it is highly likely that you will wish to connect something else. In which case, the answer is regulated 5 V.

This is because the on-board regulator is essentially capable of powering only the microcontroller itself and no more than a couple of indicator LEDs. The on-board regulator might be able to power a few other things if it had a heatsink, but on the (older) Arduinos, it does not.

Powering via the "barrel jack" or "Vin" connections is asking for trouble. The "5V" pin is not by any means an output pin, if anything a "reference" pin but most certainly the preferred pin to which to supply a regulated 5 V.

A practical power supply for the Nano (or UNO, Pro Mini, Leonardo etc.) for many simple projects is a "phone charger" with a USB output connector for 5 V, generally up to a couple of Amps though you can not feed more than 500 mA through the USB connection. If more current is involved, you have a 5 V supply capable of providing that current, you connect it to the equipment that requires the 5 V and the Arduino via the "5V" pin (and of course, ground).

Note as Mike explains, that specifically for the UNO (the Nano is more appropriate and does not have this problem) you need to disconnect that supply from he "5V" pin when you connect the USB to a PC for programming or other purposes.

12

Paul__B:
This is my pet hate. :astonished:

Please, please, please forget that the "Vin" pin and the "barrel jack" even exist. :roll_eyes:

A very real danger is that the obsolete tutorials on the Arduino site and others misleadingly imply that the largely ornamental "barrel jack" and "Vin" connections to the on-board regulator allow a usable source of 5 V power. This is absolutely not the case. It is essentially only for demonstration use of the bare board back in the "old days", the very beginning of the Arduino project when "9V" transformer-rectifier-capacitor power packs were common and this was a practical way to power a lone Arduino board for initial demonstration purposes. And even then it was limited because an unloaded 9 V transformer-rectifier-capacitor supply would generally provide over 12 V which the regulator could barely handle.

If you are dealing with this, it is highly likely that you will wish to connect something else. In which case, the answer is regulated 5 V.

This is because the on-board regulator is essentially capable of powering only the microcontroller itself and no more than a couple of indicator LEDs. The on-board regulator might be able to power a few other things if it had a heatsink, but on the (older) Arduinos, it does not.

Powering via the "barrel jack" or "Vin" connections is asking for trouble. The "5V" pin is not by any means an output pin, if anything a "reference" pin but most certainly the preferred pin to which to supply a regulated 5 V.

A practical power supply for the Nano (or UNO, Pro Mini, Leonardo etc.) for many simple projects is a "phone charger" with a USB output connector for 5 V, generally up to a couple of Amps though you can not feed more than 500 mA through the USB connection. If more current is involved, you have a 5 V supply capable of providing that current, you connect it to the equipment that requires the 5 V and the Arduino via the "5V" pin (and of course, ground).

Note as Mike explains, that specifically for the UNO (the Nano is more appropriate and does not have this problem) you need to disconnect that supply from he "5V" pin when you connect the USB to a PC for programming or other purposes.

Again thanks so much!

So, aparently the problem is, the female connector that came with the power supply is defective, i try just plugging 1 Led so see if it light up or blow, didn't matter much, but i wanted to check if the power supply was working (i dont have a mutimeter right now) so the led light up directly plugged in the male jack of the supply, but i didn't on the female. So ill go tomorrow and buy another one.

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Note there are two types of female plugs defined by the diameter of the hole 2.1 and 2.5mm. The Arduino uses a 2.1 mm pin and so that is the hole size you need. If you have a 2.5mm hole it can appear to work but it will be intermittent contact and so might to appear to be faulty.

14

ryuushinno:
Now the power supply i got is 5V, 10A...

Confused.
Why are you talking about the DC socket.
Are you still thinking of powering the LED strip THROUGH the Arduino?

The 5volt supply connects directly to the LED strip, and connects directly to the 5volt/GND pins of the Arduino.
Like the picture in your first post.
Leo..

15

Grumpy_Mike:
Note there are two types of female plugs defined by the diameter of the hole 2.1 and 2.5mm. The Arduino uses a 2.1 mm pin and so that is the hole size you need. If you have a 2.5mm hole it can appear to work but it will be intermittent contact and so might to appear to be faulty.

No no, i meant the female to conect the male from the power supply to the led strip, that the one faulty, im not powering the arduino from the jack but from de usb, and know i now i have to unplug it when i connect the arduino to de 5V pin and power it with the supply.

Wawa:
Confused.
Why are you talking about the DC socket.
Are you still thinking of powering the LED strip THROUGH the Arduino?

The 5volt supply connects directly to the LED strip, and connects directly to the 5volt/GND pins of the Arduino.
Like the picture in your first post.
Leo..

Oh no no i want to power the led with the power supply, but i didn't know the female plug was faulty (the one that came with the supply, not the arduino one), i was asuming that the power were comming from the supply, but that was not the case, so i will buy the a new female plug and reconect all again.

I was powering the leds from the arduino, but that was completetly unintended.

16

So on an update yes, that was the whole problem now the arduino even get power from the 5V pin, and just like i was predicting, got a bit of a voltage drop, but at the lastest most far LEDs, like from the 130 to de 150 and not starting in the 40 led (all LED white full bright), that one does need power injection, but is aceptable for now.

Thanks for the comments and recommendation!!