My boards are overheating and dying

This is my first post as I'm new to Arduinos. I have what I thought was a simple project that has a PIR each end of the staircase which causes an addressable LED strip to light up in the appropriate direction.

The problem is that after a day or so the lights stop working and I find that the board (Elegoo Nano CH340) is too hot to touch.

I have attached an image of the circuit along with the small simple sketch that the board runs.

Can anyone please take a look and see what the problem might be?

StaircaseWhiteLightsSimpleUpAndDown.ino (2.04 KB)

The LED strip must have its own separate power supply, you can't draw enough power from the Arduino without it overheating.

Remember the ground of this extra 5V supply must be connected to the ground of the Arduino.

You have shown a Nano but you have not shown what voltage you are running it at. This is determined by a link that shorts out the voltage regulator. Have you checked that you are getting 3V3 to drive your sensors and not 5V? If so can the sensors stand this?

If you are in fact running the Nano at 3V3 then be aware that the signals in and out of the Nano will also be 3V3? In which case you might also need a level shifter to boost the signal to 5V to drive the LED strip. The type sold for I2C level shifting are marginal and should be avoided. But the chances are that it will work without one.

It is not clear how you are powering all this. You need a 5 V power supply rated to power the LED strip, connected both to the strip and the “5V” pin of the Nano.

You may have been badly misled by “tutorials” on the Arduino site and elsewhere suggesting that it is appropriate to power it via the “Vin” pin. This is absolutely not the case; the on-board regulator is essentially useless. Powering it from the USB port is limited to about half an Amp, much more than that will burn out the protection diode.

Please read the instuctions for posting your code. It is very inconvenient for most of us to examine an attachment, so I have no idea how many NeoPixels you are actually using.

Paul__B:
You may have been badly misled by "tutorials" on the Arduino site and elsewhere suggesting that it is appropriate to power it via the "Vin" pin. This is absolutely not the case; the on-board regulator is essentially useless. Powering it from the USB port is limited to about half an Amp, much more than that will burn out the protection diode.

What purpose does the Vin pin serve then, if it is not for powering the Arduino? Is that its intent, however it's just bad practice, or does it have a different function entirely?
So to clarify, you can/should power the Nano (and presumably the Uno?) from the pin labeled "5V"?

You can use Vin to power the Arduino, but you must be mindful of how much power that the on board 5V regulator must dissipate. The recommended max power dissipation for that regulator is 1W. With, for instance, 12V on Vin the regulator must drop 7V. That means with the max dissipation of 1W the max current that can be drawn from the regulator is 140mA. The Arduino needs about 50mA of that, leaving 90mA, max, for other things (and regulator will probably run hot). One and a half WS2812 pixels can use that much.

Using an external 5V supply and connecting to the 5V pin bypasses the, weak, built in regulator and makes the full current capability of the supply available to the project.

groundFungus:
The recommended max power dissipation for that regulator is 1W.

But only if it has a proper heatsink. The PCB of the UNO/ Nano/ Pro Mini etc. is not really something that could be called a "proper heatsink".

So those figures are ridiculously optimistic. :roll_eyes:

simoncollett:
The whole thing (inc. 120led 2metre strip) is getting power purely from the 5v USB input on the Nano. From your reply it seems I have indeed been duped by Youtube tutorials. That was where I got the idea and the lights worked fine for a week or so before dying. So, should I continue with the circuit I have and simply add an extra 5v supply to the LED strip or should the LEDs be on a completely separate power circuit with only the data line connected to the Nano?

OK, you might just clarify a few things here. :grinning:

What is the current state of the system? Is it working when it cools down? If not, can you actually program the Nano when disconnected from the LED strip, such as to run the "blink" test? If that fails, you will presumably need a replacement Nano (clone).

Now, a 120 LED strip would draw about 6.5 Amps at full white brightness, so to be safe, you want a regulated 5 V power supply capable of providing that (and connecting that, always both 5 V and ground, to both ends of the strip and preferably the middle as well), so a 10 Amp nominal supply would be appropriate. As explained in #3, this supply not only can but should be used to power the Nano with the three wires from the start of the LED strip where you connect the power, back to the Nano - ground, data and 5 V to the "5V" pin.

We are curious as to what supply you have been using so far. :astonished:

You should also have a 470 µF or so capacitor between 5 V and ground where the data feeds the strip (if the strip has connectors attached, it usually has two sets of wires, such as a white and red for connecting the power and the capacitor, and white, red and green with a plug for connecting the controller; the colours may differ) and a 330 or 470 Ohm resistor in series with the data wire.

Back to you!