2 blown D1 mini's, NEED HELP URGENTLY

Hi folks,
I am trying to run 72 Neopixels at half brightness on a D1 mini clone and have so far today managed to blow 2 of them. I don't have a schematic to show but I will describe it the best I can.

The Set-up
I have a standard USB socket wired to the 5v and Gnd on the D1 to power it with a 5v 2.1A usb plug I have. I also have the same 5v and gnd wires with a 1000uf 6.3v cap going to a 3 pin connector for the pixels. There is a 470 ohm resistor from the D4 pin, on the d1 mini, to the pixel connector as well.
I have WLED 0.12.0 installed with NodeMCU PyFasher.

The Problem
Both D1s have been wired exactly the same way.
The first d1 I used was working fine with the WLED app for about half an hour or so, then I turned the lights off and left them plugged in. After another half hour ish the first 2 pixels lit up on their own. I tried to connect WLED to test the strip but it said my lights were offline. I unplugged the strip and plugged back in again, still the first 2 pixels were lit and there was no signal. On the d1, top right just above the CH340 chip pin 1 there is a tiny black component, (not sure what it is) that was now covered in something white. With power connected, that part glows orange.
++++++++++ R.I.P D1 Mini No 1 ++++++++++
The second d1 I tried worked for about 2 minutes then lost contact. Now WLED will find the d1 and apparently connect, but the d1 power light fails to light, (it does work, I tested it with the blink sketch) and there is no output to the pixels.
++++++++++ R.I.P D1 Mini No 2 ++++++++++

I am making a gift for my friends 12 year old daughters birthday and I have 5 days to finish it. I have 1 d1 left and I really don't want to blow this one. Can anyone PLEASE offer any solution or info or links that will help me fix this. I can't upset my friends kid, and she is expecting it.

Thanks in advance to everyone that views or replies to this post.

Do not run the Neopixel current through the D1.
The 5V input via the USB plug is not designed to carry the current of 72 Neopixels.

You need to power the LEDs externally directly from the powersupply, and feed the 5V from the power supply to the D1 5V pin.

Did you do this calculation?
Each Neopixel LEED needs up to 60mA.
72 x 0.06 = 4.32A

So your power supply is not even sufficient if you make all 72 flash white.

That is up to 4.32A running through a D1 PCB that is only designed for possibly 100mA.

Tom... :smiley: :+1: :coffee: :australia:

Thanks for your reply Tom. That explains quite a bit for me.

I had worked out the power requirements before hand and I did say

I figured 2.1A would be enough 'cos all 72 pixels will never be fully white at the same time. My Arduino Uno somehow managed to run all 72 pixels at 150/255 brightness with similar displays to some on WLED, using same power supply connected through usb.

The 5v from the external usb was directly connected to the 5v / Gnd pins on the D1, not to the onboard usb. Then they went to the pixel connector, and the cap was placed at the 5v / Gnd pins as well.
So in a way they were both wired straight to the power supply ( a 2.1A 5v usb socket in a plug extension unit I made at work,( which is what I did for a living a while ago)).

Would I be right in saying I can use 2 sets of wires from the external usb socket, with 1 set to the pixel connector, and the other to the D1 ?

If so, where would be the right place to put the wires on the D1, should I put them to the D1 usb socket or the 5v / Gnd pins ?
And where is the best place for the cap ?

This is the first project I am giving away so it must work properly and safely, even more so because it's for a 12 year old.

Thanks again for your reply, now I am part way to understanding and fixing my D1 rookie mistake. I only got my D1s 4 days ago, used for 1 and a half days and killed 2 of them already. Now I know why I've stayed with Arduino's for so long.

One point, When you run an LED at 50% brightness it usually runes at full brightness (and current) 50% of the time and off 50% of the time so you will need a supply that will support 100% brightness.

I don't know what hardware you have but it is usually best to troubleshoot with a partial load, like 2 neopixels.

Are you sure the D1's are dead? From what you say the D1 should not be in the power path. Can you load the blink without delay example and have it work / not work.

I would not power such a load from anything that has USB in the title. I suggest you go directly to a 5V supply.

If I said something that doesn't sound right for Neopixels that is because I've not used them for any project. But I've controlled power from various Arduinos and understand the pitfalls one can encounter.

Thanks JR, I understand what you are saying regarding current but Neopixels are different to LEDs. Here is a quote from the Neopixel Uberguide :-

'Each individual NeoPixel draws up to 60 milliamps at maximum brightness white (red + green + blue). In actual use though, it’s rare for all pixels to be turned on that way. When mixing colors and displaying animations, the current draw will be much less.'

I have already tried the blink sketch and it does still work on the second D1 but the first 1 is most defo dead. 1 component glows orange when powered up
The usb supply I am using is actually a proper 5v power unit. It has a usb connector for ease of use. It is a real manufactured piece that I got from my job.

nevertheless you should use a power-supply that is able to give the maximum current.
Or other solution reducing the number of neo-pixels

What? orange glowing? If I remember right the Wemos D1 mini has just a blue LED on the ESP8266 modul So orange glowing must be an extremly overheated component that is glowing because of a temperature of 700 degrees??? very strange. This would cause a "burned" smell

best regards Stefan

The glowing orange thing is the diode just top right of the CH340 chip pin 1. It was covered in something white and it did smoke and smell.
Now the really strange thing is that the D1 still works, flawlessly, so far.

If Neopixels require a full current supply, how come an Uno can run 72 pixels at 150/255 brightness with no power drop at the end ?
And can I run the D1 and the pixels from the same supply at the same time by connecting to pixels first ?
Or use 2 sets of wires from the supply, 1 set to pixels and the other to the D1 ?will that still pump too much current into the D1 ?

Thanks for help so far, I am new to the D1 and this has already taught me a lot, keep the help coming.

I'm pretty sure that you can take pictures with your smartphone and copy the pictures to your computer.

Take a picture of your power-supply-wiring. Transfer to your PC copy picture to the clipboard and just paste the picture into a posting. The new forum-software is able to upload the picture

In addition draw - freehand - a schematic of how you suggest to connect the power-supply
In this case words are not precise enogh or can be mis-understood.

best regards Stefan

I don't have the circuit built up at present but this is the supply I want to use. The charger is a real manufactured item made specially for the company I used to work for.

I am no expert at schematics but here is a drawing of the circuit. Hope it helps.

My main objective is to run both the pixels and the D1 from the same supply.
Above circuit works perfect with 12 pixels, but will it still work with 72 ?


Do you have a DMM to measure the 5V rail while your LEDs do their thing?

Tom... :smiley: :+1: :coffee: :australia:

It's not the voltage that concerns me, it's the amps.

Will the above circuit put too much current in to the D1 ?

Your schematic is fine, much better than a lot we get here. I know you said that you don't have the circuit built but a photo of it built might reveal the problem. Indicating on the photo what gets hot would also be useful.

As others have commented 72 will overload the supply if they are all on, you need to be careful about this. It does not explain things getting hot.


But monitoring the voltage will tell you if you are overloading the power supply.

Tom... :smiley: :+1: :coffee: :australia:

Current doesn't work like that, if the voltage is correct the D1 Mini will take the current it needs. I don't know about the other here trying to help but I would like to see the actual built circuit.

Thanks Perry, the diode on the D1 was glowing due to a faulty usb cable that I discovered.
Now there is nothing that gets hot.

Do I connect the DMM to the pixel strip or to the D1 ? And what setting do I use on my cheepo thing ?

I will breadboard the circuit this afternoon (UK time) and post some pics.


Select 20V DC range and place the black probe on the power supply gnd and the red on the 5V at the join where the D1 and LED strip 5V connect.

A picture of your project would also help.

Tom... :smiley: :+1: :coffee: :australia:

Apologies for the late post of the pic. This pic is my circuit on a breadboard, as it was when the problem happened.

This is the circuit that I am hoping to use.

Inside the yellow heat shrink is a 470ohm resistor, the cap is 1000uf 6.3v and the wires at bottom right are to the pixels.

The project is a set of 6 diy Nanoleaf triangles, all individual. Unfortunately all my triangles are fully built and the wiring is covered, but this is not my own circuit in the triangles. I got it from a project on Thingiverse by 'BiscuitsOnTheFloor' from 2019 here.

They all have 1 input and 2 output sockets. Mine are wired exactly the same.

All I really want to do is run the pixels and the D1 from the same supply at the same time. If it's not possible with this circuit, is it possible at all ?


I don't see anything obviously wrong, maybe someone else can. Which component burned?

You can't put more than maybe half an amp through breadboard contacts without getting problems, but I would not expect that to damage the D1 Mini.

The second image is a better way to wire it as the LED current doesn't come near the D1 Mini.

The component that glowed was the diode top right of the CH340 chip pin 1.


I have put the DMM on and I get different readings in different places.
All 6 triangles are on white at 140/255 brightness and powered by a PC usb3 socket (I don't want to risk using 2.1A until I know it's safe). On the pixel connector I get a steady 2.73v, at the cap I get an average of 3.2v. Where the D1 and pixels meet I get around 4.2 and the same at the D1 5v pin.
Does this sound right ?
I've only been playing with circuits for around 4 months now, everything I did before was usually powered straight from an Arduino.