PSU - controller - led wattage and noise

[amarx]

Hi all,

I've got two led strips: a (A) 24V 167W RGB-CCT (6 wires) led strip and a (B) 24V 140W CCT (3 wires) led strip. I have tried to connect both to a Meanwell 200W power supply with a wifi rgb-cct controller in between that supports maximum 6A/Channel with a total maximum output of 15A.

There is a strange high pitch hiss sound coming probably from the power supply. I can hear this sound when putting the A led strip at maximum brightness and when I change brightness with the B led strip (from high brightness to lower one).

Do you know why there is this sound? could this be due to a not enough powerful power supply? or perhaps the problem is the controller?

I could also buy another power supply if necessary but I haven't found any rgb-cct controller more powerful than the one I've bought.

Thank you in advance

 

[sagor1]

A 200W power supply at 24V cannot provide 15A, that would be 360W total. 6A is ok, but not dual 6A.
The maximum you can draw from a 200W 24V supply is about 8.3A.
Now, if just running one LED strip at a time, the 167W strip may be loading the PSU to almost maximum at which point the switching regulator may be changing frequency of its oscillation. On certain PSU, one can hear the switching of the power transistors, which often indicates either an overload or a poorly designed PSU.

 

[amarx]

sagor1

Thank you very much for your reply. In your opinion then it due to an overload? in that case, buying a more powerful PSU should make the trick.
My doubt however is about the 140W strip. I sometimes hear the noise also there and it is strange as 200W is more or less 40% higher than 140W, and it should be enough (in theory from what I've read).

The PSU should not be so bad. The specs are the following ones:

Mean Well RSP-200-24 AC / DC

power supply 200W DC 24V MeanWell power supplies of the LRS series are a line of high performance professional power supplies , with a perforated aluminum structure, with air dissipation .
They are suitable for continuous use and are also suitable for use in the industrial field.
This power supply features overload, overvoltage and short circuit protection .

The power supply is equipped with a Volt regulator (Vadj) which allows for an output voltage from 20V to 26.4V.
It is compatible with all led strips and devices withconstant voltage DC 24V .

FEATURES:
- Power: 201.6W
- Maximum Current: 8.4A
- Driver type: AC / DC
- Input voltage: AC 85-264V
- Output voltage: DC 24V
- Dimmable: no
- Number of outputs: 3 outputs
- Structure : aluminum
- Degree of protection: not waterproof IP20
- Operating temperature: -30 ° C + 70 ° C
- Effectiveness: 89.5%
- Dimensions: 215 x 115 x 30 mm
- Warranty: 3 years
- Certificates: UL60950-1, TUV EN60950-1 approved,
Compliance to EN55022 (CISPR22) Class B, EN61000-3-2, -3,
Compliance to EN61000-4-2,3,4,5,6,8,11, EN55024,
light industry level, criteria TO

 

[sagor1]

All switching power supplies have some "whine" or buzzing in their circuits, it is just a question of how loud or audible that noise is. In some cases, you cannot hear anything. In other cases you hear a high pitch whine only if close to the PSU.
Try a test with a light load, maybe around 2 or 3A load, see if the noise changes. See if the noise increases as the load increases. Note if it is the pitch of the noise (frequency) or just the loudness that changes. Most switching supplies run at frequencies above the human hearing range, but vibration/oscillations of components may produce that noise.
If the noise is only noticeable under larger loads, then the PSU may not be what it says it is, and it is running "hard" to provide the higher currents (wattage)

Why do some AC adapters and power supplies generate a whining noise, and what can I do about it?

I have many different AC adapters and power supplies for a variety of devices, ranging from small 5V/1A USB chargers to laptop power adapters and desktop PSUs. However, I often hear a whining noise...

superuser.com

 

[amarx]

Thank you for your suggestions.

Try a test with a light load, maybe around 2 or 3A load, see if the noise changes.[ /quote] less brightness should be less amperage right? in that case there is no noise. It looks like high amperage is the main problem. In this case I just need to buy a more powerful PSU I guess.

In any case, if this is the problem, I don't understand however why there is the noise in the less powerful strip when I change brightness. If I recall correctly, when I go from max brightness to lower one .

PS the link provides a really good explanation, thank you!

 

[amarx]

I have an update. I've bought a new PSU (same brand of the other). This time 320W and IP65. No coil whine at all.
I have to understand now why the other PSU produces that noise at max brightness.

I would exclude now the controller. Two options are left:

1) it's because the PSU is not powerful enough
2) it's because the case is IP65, so that might reduce the noise
3) both of them

What do you think about?