12V RGB LEDs

Hi,
I have a 12v 5m RGB LED 5050 300PCS/SMD Strip that I wish to connect to my arduino. I understand that the arduino uses 5V and I have bought a few IRLZ44N MOSFETs. I also have an external power adaptor that can supply 12v/0.83A which came with the LED strip and works perfectly when used directly. I have been following a guide on adafruit and I can't seem to get it working.


The strip on the right is exactly the same as my LED. Since my adaptor says 0.83A I'm assuming my LEDs draw less than 1A so I don't need to follow the warning note. In the diagram it connects the +!2V of the LED to the 9V on the arduino. I cannot find this 9V on my arduino, I only have 3.3V and 5V on my Arduino Uno.

FShiwani:
In the diagram it connects the +!2V of the LED to the 9V on the arduino. I cannot find this 9V on my arduino, I only have 3.3V and 5V on my Arduino Uno.

"V in", assuming that your wall pack is connected to the Arduino barrel jack

Isn't that power for the arduino? Wouldnt that fry it since its a 12V wall adaptor and arduino only supports 5V/3.3V

EDIT: Finally got it working. Plugged the wall adaptor into the arduino and it works perfectly. Thanks for the help.

Well, I accidently removed the LED strip and left the wall adaptor plugged in and some small smoke started coming from the AMS117, so I removed the plug immediately and it seems to be fine now. nvm. Its fried. RIP arduino.

FShiwani:
I accidently removed the LED strip and left the wall adaptor plugged in and some small smoke started coming from the AMS117, so I removed the plug immediately and it seems to be fine now. nvm. Its fried. RIP arduino.

Don't see why that should be, depending what "removed the LED strip" really means.
The ladyada dwg shows the LED +V at Vin.
I would prefer that they showed the LED +V tapping into the wall pack (or the wall pack forking with one end connected to V_in/barrel and the other to the strip.)

You should check the wall pack output. The AMS may have been trying to do a lot of current (5metres of LEDs worth) and resulted a thermal shutdown number (perhaps heating up some solder in the process.)

Wall adapter is probably not regulated and rises to 18 or 20 V on no (or Arduino only) load.

Barrel jack and Vin have a diode in between them. Vin bypasses the diode, and feeds the 5V regulator directly.
I would put the questionable source into the barrel jack.

EDIT: Finally got it working. Plugged the wall adaptor into the arduino and it works perfectly.

How? A 300 led rgb strip is going to need 6A, how can a <1A supply have worked?

PaulRB:
How? A 300 led rgb strip is going to need 6A, how can a <1A supply have worked?

It always worked perfectly when connected directly. Never had any issues. It came with the LED Strips. Heres what it says on the back:

CrossRoads:
Barrel jack and Vin have a diode in between them. Vin bypasses the diode, and feeds the 5V regulator directly.
I would put the questionable source into the barrel jack.

Thats exactly what I did.

The way I had my LED strips hooked up is the 4pins of the end of the strip were plugged into the breadboard, and before I removed the external power adaptor from the barrel jack I removed the LED strips from the breadboard instead putting them back in the box. A few seconds later a very small stream of smoke starting coming from the AMS117 regulator just below the barrel jack. I quickly turned it off and a solid light is present on the arduino beside the letter L under the TX,RX LEDs. I’m not sure whether its a coincidence or not that the smoke started coming at the exact same time as I removed my strips or whether it was just getting extremely hot while I was using it and it decided to die at the same time as I removed my strips. Not sure where the fault was. Either I shouldn’t have removed my LED strips first and should have removed the external power first or the AMS1117 was faulty or my external power adaptor was unreliable. Either way my PC doesn’t detect the arduino anymore but thankfully my USB ports are fine.

Any thoughts on having the barrel jack connected (live) as well as the USB?

Yeah thats how I had it. Thats why it died probably? Or do you want me to try it?

FShiwani:
It always worked perfectly when connected directly. Never had any issues. It came with the LED Strips.

Well, that seems woefully inadequate to me. A 12V strip is organised with the leds in groups of threes, so your strip has 100 groups. Each group will need up to 20mA each for r, g & b, so that's 100 * 3 * 20mA = 6000 mA = 6A. Have I calculated that wrong?

PaulRB:
Well, that seems woefully inadequate to me. A 12V strip is organised with the leds in groups of threes, so your strip has 100 groups. Each group will need up to 20mA each for r, g & b, so that’s 100 * 3 * 20mA = 6000 mA = 6A. Have I calculated that wrong?

Seems fine to me. No idea how this is working if supply is 0.83A and it requires 6A. The info on the packet of the strips says.

FLEXIBLE 5050 SMD LED STRIP LIGHT
1ROLL/300PCS SMD
5M
VOLTAGE: DC 12V
POWER: 72W/ROLL
5050-60smd-ip65-rgb

Power is 72W per roll. Power = Voltage x Current. So Current = Power/Voltage = 72/12 = 6A. I have no idea whats happening anymore. Either is supply is labelled wrong or ?

EDIT: Isn’t that max current draw? If all lights were bright white it would draw 6A. But it rarely is like that. It came with a remote and controller and it says 2A max per colour. I can use the fade on the remote that switches through all colours fading into each other colour, so clearly more than one LED can be on at a time with this supply.

So the controller can demand 2A per colour... sounds like if you set it to max brightness on white, the psu could burn your house down after a couple of hours.... Chineese hoverboard, anyone? (Aplologies to any Chineese members for that blatant racial stereotype!)

FShiwani:
Yeah thats how I had it. Thats why it died probably? Or do you want me to try it?

No, I don’t want you to try that.
I haven’t really analyzed that. It’s OK with a Nano given its “auto-select” diode, but the Uno doesn’t have that.
Do you have an official Uno or a clone?
If you decide to take another shot at this, route the wall pack as I have shown in the dwg attached. Adafruit has a couple of Notes (!), but no diagrams for the unknowing.

[Maybe I should make an “external power shield”. I’d probably sell 3 in 3 years.]
Still, it seems to me that there’s something else going on here.

"It's OK with a Nano given its "auto-select" diode, but the Uno doesn't have that."
Uno has Vin/2 > 3.3V detector to select between Vin for power or USB for power when both are connected.

CrossRoads:
Uno has Vin/2 > 3.3V detector to select between Vin for power or USB for power when both are connected.

Good to know.
Well, that 1117 smoked for some reason ("something else going on"), but I don't want anyone to get excited.
Something touched something else, albeit inadvertently, and 'poof'.

Do any of you know where I can get a decent reliable 12V power adapter for these LED Strips?

I found this link

in this link