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Help with NeoPixel through hole sockets, prevent short out
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Help with NeoPixel through hole sockets, prevent short out

by redsholdrd on Fri Jul 05, 2019 2:12 pm

Hello Ada-people,
Big fan. Thanks for all the work you do!

I'm making a glowing ET finger that will poke through a loose fabric in an installation project.

For moving the "finger" I'm using these mini pan-tilt servo kits https://www.adafruit.com/product/1967

The fingers are rigid, clear, plastic tubing, cut to drinking straw length.

For the glow tips, I am using NeoPixel through-hole LEDs https://www.adafruit.com/product/1734

I am wiring the 4 leads by using shrink tubing to cover and secure the stripped wire and led leads, and running the wires through the "finger" tubes to a board connecting the power and ground and data in/out. I chose this connection option because it seemed safer/easier/less breakable than soldering the four leads and taping them or shrink tubing them to make sure the solder points don't break or touch and cause a short.

However, in an early test, the ground and 5V leads did touch and short out and burned the NeoPixel in the pics below.

(I followed all the "Basic Connection" practices for caps/resistors from the NeoPixel guide here: https://learn.adafruit.com/adafruit-neo ... onnections)

Can you please recommend another solution where I can make a glowy color-controllable finger, while safely connecting the leads of the LEDs so they can be moved around, withstand a little bit of pressure on them, and not be in danger of shorting out?

Is there a small 4-lead socket they could fit into that could fit into, or around the thin plastic "finger" tube?
Or some other suggestion for wiring these LEDs safely?

I am willing to use another type of NeoPixel other than through hole, but I liked the finger-tip shape of these LEDs.

I very much appreciate any suggestions.

Thank you!
Jacob

neopixel burnout1_1.jpg
neopixel burnout1_1.jpg (858.17 KiB) Viewed 193 times

neopixel burnout2_1.jpg
neopixel burnout2_1.jpg (888.05 KiB) Viewed 193 times

redsholdrd
 
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Re: Help with NeoPixel through hole sockets, prevent short o

by adafruit_support_bill on Fri Jul 05, 2019 2:38 pm

The heat-shrink approach should work - as long as you make sure that the tubes are cut long enough to cover the entire lead. You could also cut the leads shorter. You only need a fraction of an inch exposed to solder to.

For joints that are going to be subject to stress and movement, you can further seal and stabilize it with something like hot-glue. Hot glue can be a bit messy to work with and hard to control. But it is soft enough that you can trim off any excess with a sharp blade.

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Re: Help with NeoPixel through hole sockets, prevent short o

by redsholdrd on Tue Jul 09, 2019 9:19 am

Thanks A_S_Bill!

I'm trying the hot glue as a securing/insulating agent for these connections and will let you and anyone else looking know how it goes.

-btw, I LOVE your MULTI-TASKING THE ARDUINO tutorials!

I've been looking at them very closely for this project, which if you haven't guessed already, combines servo control and NeoPixel control (part 1 and 3 of your tutorial sequence).

I've hit a bit of a slow patch trying to time multiple servos to do the same movements at the same time using millis() calculations and not delays...for instance coordinating a pan/sweep of two servos. The pan/tilt servo combos each have slightly different position numbers that correspond to the same range amount of movement. For instance one servo will have a ~180 degree pan between position #s 440-600, another servo will have the same movement from 225-400...so different values AND a different span of numbers between min and max for the same movement. So when I define a class and public, and update it them in the loop, they different servos quickly lose sync and the movement is pretty random.

I'm still trying to work it out on my own, but might wanted to mention that I might have a more specific question to post about the programming soon, and say again that I love these tutorials!

Cheers!
J

redsholdrd
 
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Re: Help with NeoPixel through hole sockets, prevent short o

by adafruit_support_bill on Tue Jul 09, 2019 10:05 am

. . . different values AND a different span of numbers between min and max for the same movement.


The 'sweeper' example assumes a fixed increment and a full 180 degree sweep. Only the update interval is variable. If you want variable sweep distance over the same time frame, you would need to recalculate the increment. I'd probably use something like the map function for that: https://www.arduino.cc/reference/en/lan ... /math/map/

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Re: Help with NeoPixel through hole sockets, prevent short o

by redsholdrd on Sat Jul 13, 2019 11:25 pm

I'm running 8 of the NeoPixel through-holes in 8 of these fingers.
The last neopixel flickers a lot when running the test program.
My guess was that the problem might be the total length of the data cable: it's about 2-3ft between each led so the total data wire length (they are all wired data out to data in) is about 20ft.
When i try to bypass a bit, the last led stops flickering.

--If this is the case, is there some way to boost the data signal strength so it can reach longer distances?

Thanks!

redsholdrd
 
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Re: Help with NeoPixel through hole sockets, prevent short o

by redsholdrd on Sat Jul 13, 2019 11:50 pm

...ugh, just as i finished writing the last question, that same neopixel in question burned out.

with the earlier 2 leds i fried (above), i realized that i incorrectly wired them, so I figured that was the problem.
It had the same behavior as this one just now: flickering wildly while the others followed the test program, then frying out on the ground terminal.

I also noticed it only burned out when i used an external power supply, not while powered by 5V from the Arduino.
It's a 5V, 10amp big guy i was hoping to us to power the servos and the neopixels. I know this shouldn't be an issue because the voltage is the same, but it is a weird coincidence.

This time this last led was just on a breadboard and wired correctly (see pic below, flat side is on the right, white is data in, nothing attached to data out because it is the last led I am using). I put it on the breadboard to check to see if shortening the data cable stopped the flickering, which it did.

I have added the 1000uF cap on the whole circuit, the smaller 104 caps between the power/ground of each led, and have been doing my best to follow the NeoPixel Uberguide.

Any suggestions about:
1. How to boost the data signal so it doesn't flicker at the end of the chain of leds?
2. Why these leds keep burning out when they start flickering (and are powered by the external 5v/10A source)?

Thanks!
Attachments
Neopixel burnout3.jpg
Neopixel burnout3.jpg (857.33 KiB) Viewed 126 times

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Re: Help with NeoPixel through hole sockets, prevent short o

by adafruit_support_bill on Sun Jul 14, 2019 8:18 am

Which pin is the one with the burn marks. Is that the 5v pin or the GND pin?
Is your 5v/10A supply well regulated? Some supplies run a bit overvoltage when lightly loaded.

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Re: Help with NeoPixel through hole sockets, prevent short o

by redsholdrd on Sun Jul 14, 2019 10:19 am

It's the ground pin on the led, touching a bit of the data out pin on the right.

I'm using this power supply I bought from Adafruit so it should be well-regulated.
https://www.adafruit.com/product/658

I tested a few variables (data cable length, power from arduino vs. 10A power supply)

The consistent thing seems to be when the led flickers a lot (or isn't connected to the data in/out stream by mis-wiring etc) it burns out. Quickly when powered by 10A, slower when from the Arduino.

Thanks!

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Re: Help with NeoPixel through hole sockets, prevent short o

by adafruit_support_bill on Sun Jul 14, 2019 10:54 am

Neopixels in general are not very tolerant of abuse. Miswiring them - even momentarily can cause damage. The damage is not always immediately fatal. A 'wounded' pixel might continue to light up and be semi-functional for a while.

One thing to be especially careful of is making changes to connections on a live circuit. The "Best Practices" page in the uberguide describes the proper order for making or breaking connections. Common mistakes are to have an active signal connection to a pixel that is not powered - or power to a pixel that is not grounded.

Pixels can fail 'open circuit' in which case they just become unresponsive. Or they can short out internally - in which case a high current power supply will quickly cause a meltdown. Since the die is attached to the ground lead, that is where the heat damage is visible.

Flicker toward the end of the chain with through-hole pixels is often caused by inadequate bypass caps between +5v and GND. The recommended 0.1uF caps should be as close to the pixels as practical to be effective. I do not see them in your photos, so I'm guessing they attached some distance from the pixels themselves.

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Please be positive and constructive with your questions and comments.