SparkFun Forums

[shiftline]

Hey guys. I recently got a reef led light. The light is powered by a 39v 2.5a transformer the connects to the led board. The light is then controlled via a controller box which I believe is pwm.

Something on the led connector board is emitting a high pitch noise then the light is dimmed lower than 95%

All 4 channels seem to do this but 1/2 are extra loud.

The board only has a few components
The little linear drivers Part# AMC7140DLA

Datasheet > https://www.dropbox.com/s/hziv3k07grlsl ... A.pdf?dl=0

And a few capacitors/resistors. What the heck is making this noise?

[shiftline]

So I have pinpointed the source to the smt caps. If I put pressure on the board directly beside it the sound quiets way down. I believe the caps are vibrating and transferring this to the pcb which is amplifying it

Is there any way to fix this?

ImageUploadedByTapatalk1424617854.769845.jpg

ImageUploadedByTapatalk1424617867.335173.jpg

[n1ist]

Ceramic caps make good piezoelectric tweeters when you don't want them to. On a previous project, I ended up potting the cap to quiet it down.
/mike

[shiftline]

Hey mike. Is there anything I can with out knowing what the vale is. Did you simple just add an adjustable or to it?

[Mee_n_Mac]

By potting he means this ...
http://en.m.wikipedia.org/wiki/Potting_(electronics)

[shiftline]

Would you use hot glue, silicone, superglue?

[shiftline]

So hot glue dampened it. But I can still hear it from about 3' away