Noisy LEDs (literally!)

[KebyMilla]

Woah, blew my eardrums!

[madamerotten]

There may be either magnetostriction and/or electrostriction in some of the components. Given a sufficient step-change in applied voltage, many electronic components will have some mechanical displacement resulting in sound.

[Doublehp]

It's not the leds themselves that do the sound, but the current variations in various parts used for the leds: self, capacitors, wires, strips ... all have mechanical réactions (producing sound) when curent and voltage variations. Capacitive parts (including wires: conductors in front an other one) are subject to electro static repulsion; selfic parts (including wires that are twisted one around an other) are subject to magnetic fields.

All this make coper trying to move, and produce noise.

[maclover201]

It sounds like PWM.

[TheBypasser]

Well, in fact to prove the trannie part I'd say running a PWM driver made a PSU feeding the whole thing make an audible noise. More of it, usually it's made by any coils involved, like trannies, chokes etc.

[rminb010204]

LED efficiency is just too high, I doubt you will get much electrical potential becoming sound.

[sickliberty]

My first guess was that your device is using relays; ICinto also has a very good point. LED's don't make noise dude.

[luzgrioni]

it´s so good!

[D4V1DR0B3R7S0N]

Either your using a switched mode power supply or PWM (Pulse-Width Modulation). Its not the LEDs.

[natn0]

it's not the LEDs that make noise. ya dummy

[cyberteque]

It's easy to get an LED to make noise, just put a couple of hundred volts across it! lol

[ICintoTheFuture]

What is happening is that the power supply is dipping when all the LEDs switch on (higher current demand). You can see this as the LEDs dim. The click and HF whistle you hear are the windings in the transformer banging against each other. It is quite common in high current PSUs. The power supply is probably 'bursting'. ie switching at, say, 300kHz, but this 300kHz is happening in bursts. If the bursts are at 10kHz (the audio band) you will hear it. Add more decoupling or use more than 1 PSU

[Repter75]

Exactly, it's not the LEDs that's making the noise.

[baronmaniac]

I think the power supply is making that noise when the current load changes.

[markjurrens]

I have heard semiconductor material itself make thermoacustic emenations due to the rapid expansion and contraction caused by heat generated by the flow of electrons through the material.

[BentQuarter]

lol

[Morxy49]

wow that was alot of hard words

[markjurrens]

Hej Jag har precis fått reda på hur man översätter engelska till svenska med hjälp av Google Översätt, trevligt att höra från dig!

Hi there I just found out how to translate english to Swedish using google translate, nice to hear from you!

[rroge5]

that sound wouldnt be from the led's themselves, it would be from the wires making a magnetic field and moving in relation to the nearest magnetic objects.

[AlienRelics]

All I can hear is a hum that sounds like a power supply with an overloaded or substandard transformer. Is that what you mean?

[Jomar4444]

volume your speaker even louder and you can here

cringing sound

[Yakshinian]

That's what he is talking about.

[madmax2069]

no its a very high pitch squeal that changes pitch with the LED's is what he is talking about not the low rumble sound you all are describing, get your hearing checked.

its called EFM, use google to learn what it is

[digitl]

You want some great sound off EMF then put an acoustic guitar pickup next to your PC when the fan is running. Full spectrum of cool sounds. Then patch through a guitar fx box and you got something useful.

[radby]

It looks like they don't come on too bright for a second. Is it possibly that at power-on you switch them on-off so fast that they come on dimmed and make this audible noise?

[Jimmypage512]

...

the LEDs produce electrical EMF (radio interference) when ever they switch on - this causes the condenser microphone in your camera to oscillate which produces this fuzzy sound your hearing.

[AMDkicksass]

my intel main board makes the same noise its not the led's

[danisdan01]

Are you sure its the LEDs themselves making the noise. Becuase from the sound of it, it sounds more like a transformer.

[davidjmerrill]

hmm - yes, you could be right about it being the transformer - I didn't home in on the source of the sound as carefully as I could have..