Edit can someone move this pls to General Electronics, i had the wrong tab opend
Hello fellows
Few weeks ago i build my LED Matrix and everything worked fine so far (140LEDs, parallel).
Some days ago i mounted it on the wall and i had to make the power cable for my arduino + led matrix longer.
At the moment i've got an awkward problem. If all cables go seperate to my power supply (RS75-5), then i get weird LED flickering. First i thought my power cables are near the data cable, but that didnt cause the problem.
if i take the power cable from the arduino + one of the power cable for the LEDs and tape them close together, then the flickering is gone (only sometimes the last row flicker).
so i think its a problem with the power supply for my arduino
atm the arduino + the matrix is connected with the RS 75-5 (running @ 5,5V). The LED Matrix is using something around 6 amperes, so for each of the 2 power cable for the LED matrix is 3A.
So i guess it hase something to do with induction and the arduino mess up the data signal.
This is how the power wiring looks like (data cable isnt finished at that picture)
So i was thinking of using shielded power cable for the LED and Arduino.
Question is how do i proper connect the shielding with the neutral wire? and how should the drain wire be connected (some cables have them) ?
Never thought, that the power cable can cause such problems
All cables that are connected to the same assembly, must be kept as close as possible together.
Otherwise they form loops, and loops can pick up interference or behave as inductors in series with your connections.
You have not explained with a diagram just what interconnections are involved, so we are of course unable to explain in any more detail what the actual problem is that you have with ground loops.
Yea didnt think of that. As you say ground loop i remember that i had some noise with my active subwoofer, when he was in stand by and no audio source was connected. And the power supply for the LED matrix+arduino is connected to the same socket.
i will make a scematic how its wired from the power supply
if the cables behave as inductors a shielded power wire should help if i'm not wrong ?!
still awkard that the power wiring is causing that problems
All cables that are connected to the same assembly, must be kept as close as possible together.
Otherwise they form loops, and loops can pick up interference or behave as inductors in series with your connection
While that is true, this particular case does not (IMO) fit that scenario, because 140 leds x 0.020 A = 2.8A.
2.8 A going through a cable next to the arduino power cable, would not be likely to be enough to cause fluctuation in the arduino power (which is probably what is happening). The proof is that the OP says the anomaly disappears when ONE of the led cables is bundled. The OP has not stated HOW MANY LED CABLES BUNDLED WITH THE ARDUINO CABLE does it take for the problem to APPEAR ? CASE A
ALL LED CABLES + ARDUINO PWR = PROBLEM CASE B
"n" LED CABLES + ARDUINO PWR = PROBLEM CASE C
ONE LED CABLE + ARDUINO PWR = NO PROBLEM (ALMOST)
SO what is "n" for CASE C ?
if the cables behave as inductors a shielded power wire should help if i'm not wrong ?!
Shielding would prevent mutual inductive coupling.
Mirgus:
if the cables behave as inductors a shielded power wire should help if I'm not wrong ?!
raschemmel:
Shielding would prevent mutual inductive coupling.
Not for power wiring.
The degree of shielding provided by shielded cables is negligible in terms of low frequency magnetic fields as the conductivity of the braid is insufficient. You would need a superconductor.
Shielded cable will not prevent ground loops in audio circuits. You, raschemmel, should know that.
No, the problem with inductive coupling is loops. Keep the cabling together and there are no loops.
No, the problem with inductive coupling is loops. Keep the cabling together and there are no loops.
I don't see how the loops explains the flickering. What exactly is causing the flickering ?
(loops doesn't explain that. It may be the cause but it doesn't explain what is happening)
Also , the OP hasn't answered my question about how many led power cables cause the problem.
He only said that there is no flickering with only one. The definition of ground loop is excessive current due to more than one ground return. It would help if the OP would measure the current with and without the wires bundled to see how the arduino power current differs.
Keep the cabling together and there are no loops.
The OP says the problem occurs when he bundles the led power cables with the arduino power cable.
That's why I asked how many led power cables does it take (bundled with the arduino power cable) to cause the problem. Knowing the current would help. (through the led power cables and arduino power cable)
Hi,
Can you post us some pictures of your project, in particular how you have the arduino and LED power wires connected to the power supply.
I hope you are not using hookup guage wire as power supply wires to the LED array, have you got the GND from the LED array connected directly to the power supply NEG and the arduino gnd connected directly to the power supply NEG, not daisy chained.
