LED table Help needed! save my project!

Other Hardware General Electronics
1

This is my first electrical project and I have only an extremely basic knowledge of electronics to fall back on. I need some expert help. I have a project going using ArduinoMega2560 and 200 (4 sets of 50) of these exact LEDs HERE daisy chained and i have been racking my brain for weeks trying to get them to turn on. This is the project i'm working on - It is for an interactive bluetooth coffee table actually which is hosted on instructables (here is a link: http://www.instructables.com/id/Dot-an-Interactive-Coffee-Table/) I set the LED table sketch and required libraries in Arduino for the LED table i have been painstakingly crafting and affixed 196 leds to a wooden plank with hot glue (not good) to make the table.

I initially read up on WS2811 LEDs and from some posts i saw, I thought the lights were 12v. First I got this power supply which was tiny and had only 12v but 2A and didn't seem like it would power the LEDs. It was still somehow rated 12v but I returned it as the LEDs only came on dimly once then wouldn't come on again. Then I got this power supply on Amazon, and when I hooked everything up, the first 9 to 12 LEDs came on very bright. Well, after checking the chinese site that housed the ebay LEDs I'd bought, I noticed the product specs on the LEDs clearly say 5v and the power source was 12v. When I realized this I unplugged immediately and bought this EXACT, 5v 20A power supply. Now when I've connected that - none of my LEDs turn on.

Here are the specs I ended up uncovering on the LEDs:
Product Properties:
Item Type:LED String
Brand:no
Shape:irregular
Power Supply:DC
Working voltage:5V
Waterproof:no

Specifications
Working current: 60MA
Power: 0.3W/LED
Working temperature: -40- 60Deg.C
IP grade: IP68
Dimension: 12 mm
Lifespan: MTBF>50000h
Viewing angle: > 90

To run the lights, I was hooking up the power on the LEDs to the V+ on the Power source and the Data pin to PWM pin 9 on Arduino. I also changed the DATA_PIN to 9 in the sketch. I'm using the VIN pin to power the Arduino, also connected to V+ pin and grounded the board by connecting V- to GND.

First question, did I fry all 196 of my LEDs and is there an easy way to test which (if not all) of my 4 LED strips may be fried? I have a multimeter but I'm not sure which setting to use and where to test the current.

And Second, did i miss something in constructing my circuit? the HC-05 bluetooth unit I have connected to my Arduino runs with no issue but I haven't been able to get the LEDs to cooperate yet.. could that be due to the fact that I ran 12v through them first before getting the 5v unit and they were already fried? because with the 2 12v supplies, they lit up partially but with the 5v supply, not so much as a glimmer now.


This is how my circuit is constructed, except i am using the Vin Pin for power from the power source, rather than the Arduino 5v pin (which is powering my HC-05) - can anyone think of one of the many ways I may be going wrong?

If you can somehow save my project (and hundreds of dollars spent) I will be forever in your debt.

2

Sounds like you need new leds.

What you did is basically the same as connecting a 12V car lightbulb directly to the 110V/220V in your house, realize your mistake and place it in the car (where it no longer works).

3

I didn't understand the circuit even though I went to the website that you gave in your introduction.

Basically each LED (not 5v or 12V types which have an integral resistor in the package, so maybe they are all wired in parallel) normal types will have a voltage drop across them of 2volts (this varies from Led to LED). So for a 12volt supply you can have 5 leds in series and 2volts spare to drop across a series resistor, so the current in the string is this 2volts divided by the value of the resistor.
It's very difficult to fry an LED in an instant and usually takes serveral amps to due so, overcurrent usually shortens their life. It's the heat that destroys them.

LEDs are current devices just like diodes so any voltage over their forward voltage drop will drive unlimitless current through them unless a resistor is used to limit that current. You seem to have a 330 Ohm resistor to limit that current on the PWM output. Given that an Arduino output can only drive 40mA it seems that you can't have many leds on an output but there is also a 5V feed so maybe there is a driver in the LED array.

It would be nice to know how the LED strip is actually wired.

To test an LED with a multimeter you have to use the switch setting with a diode symbol on it. test the device in the forward direction and then in the reverse direction the readings should be different . The reverse direction should almost be an open circuit reading. Use this method as a rough test for testing transistors, using the base as the common connection.

Hope this helps

Dead_Ard

Dead_Ard

4

  1. Those are neopixel strings, they will not do anything without the appropriate code/library to talk
    the right serial protocol to them

  2. Any of they you have exposed to 12V are completely and utterly dead, discard.

I think your best course of action is get a few discrete neopixels and check you can drive them
before moving to expensive strings of them - always baby-steps to your destination or you
will trip and fall.
Neopixels are 5V only, Adafruit have a lot info on them.

5

I have been looking on Adafruit and all i see listed are the thin strip LED lights not the bulb individual LEDs I have. That is why I was looking elsewhere for tips on how to hook them up. Are these still wired identically to the bulbs, despite looking nothing alike? And for testing purposes, what is the best way to test data is actually going through my data pin and line (and 330 ohm resistor) without the LEDs connected? I'm going to have to get a new 50 string of LEDs and I need to find the best sketch to test them out.

Thanks

6

Adafruit does recommend using a ~470 ohm resistor on the data line of the LED strips. They also recommend using a 1000 uF capacitor on the power lines:

I think the 330 ohm resistor is close enough. Go ahead and check it with your multimeter to be sure it's good or swap it out for another one if you don't own a multimeter. The resistor is only to protect the first pixel on the string but I wouldn't remove it unless it's bad and you don't have a replacement.

puredark:
I have been looking on Adafruit and all i see listed are the thin strip LED lights not the bulb individual LEDs I have. That is why I was looking elsewhere for tips on how to hook them up. Are these still wired identically to the bulbs, despite looking nothing alike?

Yes, it's the same wiring, same communications protocol, etc. The Adafruit Neopixels are WS2812, your LEDs are WS2811 but the only difference is the WS2812 have the controller built into the LED and yours have the controller in a separate IC.

Dead_Ard:
It's very difficult to fry an LED in an instant

There's more to a WS2811 than LEDs. Just because the LEDs aren't burned out doesn't mean the controllers weren't damaged by the 12 V and those can be fried in an instant by 12 V.

Dead_Ard:
Given that an Arduino output can only drive 40mA it seems that you can't have many leds on an output but there is also a 5V feed so maybe there is a driver in the LED array.

The Arduino pin is just sending the control data. The strips are separately powered.

Dead_Ard:
It would be nice to know how the LED strip is actually wired.

Plenty of info out there. Addressable LED strips are extremely common. The form puredark is using is uncommon but the standard strips are wired the same, just in a less obvious manner since the controller is incorporated into the IC and it's all wired on a flex PCB with the only other component being one capacitor per pixel.

7

Hi,
Is this related to this?

http://forum.arduino.cc/index.php?topic=457890.0

and this

http://forum.arduino.cc/index.php?topic=460329.0

Tom... :slight_smile:
(Edited .... URL)

8

Tom, your link is corrupt. What you see is not what you get.

9

pert:
Adafruit does recommend using a ~470 ohm resistor on the data line of the LED strips. They also recommend using a 1000 uF capacitor on the power lines:
Basic Connections | Adafruit NeoPixel Überguide | Adafruit Learning System
I think the 330 ohm resistor is close enough. Go ahead and check it with your multimeter to be sure it's good or swap it out for another one if you don't own a multimeter. The resistor is only to protect the first pixel on the string but I wouldn't remove it unless it's bad and you don't have a replacement.
Yes, it's the same wiring, same communications protocol, etc. The Adafruit Neopixels are WS2812, your LEDs are WS2811 but the only difference is the WS2812 have the controller built into the LED and yours have the controller in a separate IC.
There's more to a WS2811 than LEDs. Just because the LEDs aren't burned out doesn't mean the controllers weren't damaged by the 12 V and those can be fried in an instant by 12 V.
The Arduino pin is just sending the control data. The strips are separately powered.
Plenty of info out there. Addressable LED strips are extremely common. The form puredark is using is uncommon but the standard strips are wired the same, just in a less obvious manner since the controller is incorporated into the IC and it's all wired on a flex PCB with the only other component being one capacitor per pixel.

This was super helpful. i'm learning so this type of info is very helpful. Thanks for your time!

10

Hi,
I'd suggest the OP only run one thread and get each problem solved, one at time, rather than having many threads all over the forum, trying to fix different problems with the same project.

Any code changes will need to be posted to all threads to keep everybody up to date.

Thanks... Tom..... :slight_smile:

11

TomGeorge:
Hi,
I'd suggest the OP only run one thread and get each problem solved, one at time, rather than having many threads all over the forum, trying to fix different problems with the same project.

Any code changes will need to be posted to all threads to keep everybody up to date.

Thanks... Tom..... :slight_smile:

Thanks - new to the forum and will do.