Drivers meanwell LDD....hum

Other Hardware LEDs and Multiplexing
1

Hi all,
first of all I apologize for my bad english
I have a problem with the drivers in the subject, attach the datasheet
Each driver (in total 4) is powered at 48V and to each are connected 12 led cree in series, all are controlled by a single PWM output.
The problem is that during the fading hear a slight hum (I do not know exactly where it comes from)
I already tried to change the frequency up to 1kHz (I'm not really sure I succeeded :~) but the buzz remains the same. I have an arduino Mega1280.
How can I fix?
Thank you!

LDD-H.pdf (234 KB)

2

Hum's tend to come from inductor coils....

3

I should not have inductors coils, perhaps inside the power supply but it certainly does not come from them.
If I approach with my ear to the led ceiling can not understand where it comes from, the buzz is the same along the entire length.
For this reason, I guess it's a problem of frequency

4

I have been using the LDD-H drivers for some time - they have proven to be faultless.

I have heard of a humming issue but not sure if it was resolved.

What are the specifications of your power supply?

Can you replace the LDD to see if the hum continues?

5

can you see inside the LDD?

if you can't how do you know there's no inductor coil?.. most switching applications will have at least 1.

6

Hi can you post a picture of the LED layout and its wiring.
Yes the LDD do have inductors to stop emission of switching noise through the supply wiring.
If you wanted to produce as much electrical noise as possible, a squarewave like in PWM is the best way to do it.

Also if it is a low frequency hum, wrap your hand around one of the cables going to the LEDs, see what you can feel.
Significant peak current in parallel wires can cause them to physically move against each other due to magnetic fields.

With power inverter systems parallel supply leads can actually physically move if suspended along side each other due to pulsing current.

Tom.... :slight_smile:

7

I'm back .... I took some pictures where you see the connections of the LEDs and wiring.

I noticed that the hum is slightly stronger on the side where you can see Arduino (where there are all positive leds) :~

IMAG0310.jpg
IMAG0310.jpg800×451 139 KB

IMAG0346mod.jpg
IMAG0346mod.jpg451×800 78.7 KB

8

Due to the high levels of current involved, i'm wondering if it's the wires ....

The strong magnetic fields may repell / attract causing a frequency which grts converted to mechanical energy and we hear it... swich it on and firmly grip the cables see if it stops....

9

the strange thing is that I hear more hum when the lamp is positioned as in the second photo. to hear it when it is positioned as in the first picture I bring ear.

10

Hi see reply #5, re wires and vibration...

Tom.. :slight_smile:

11

Surely it is a problem of my translation, I realized that the problem is the vibration caused by the PWM, but I do not know if the problem is out of the driver or the 48V power wires together with those of the PWM signal.

I can do some testing before rewiring of the lamp? The wires I've tried both to block them (those that are successful) that move them.

12

Hello to all
I have not solved yet, I've tried everything:

  • I disconnected everything and connected only one driver and the related LED PWM separating the signal from the power.
  • I unplugged the LEDs from the heat sink
  • I connected a capacitor on the output of the power supply
  • Twisted wires for power supply

Nobody seems to have had this problem .. surely something wrong
Do you have any other solution to propose? Whatever comes to your mind! I do not know what to do!!

I was able to record what you hear .... if it can be helpful

Voce0003.mp3 (187 KB)

13

anyone? :~ :drooling_face: