Switching PSU audible noise

I've heard this problem mentioned in Power Integrations' app notes. See

I've actually experienced more of a 'hissing' in certain cases.

If the transformer's already been varnished you're probably stuck with it.

Graham

I read in sci.electronics.design that System Alchemist wrote (in ) about 'Switching PSU audible noise', on Mon, 19 Sep 2005:

Wait 10 years and you won't be able to hear 10 kHz any longer. It may be magnetostriction, in which case you need a different coil.

It is possible the electrolytic capacitors on the secondary and/or in the regulation circuit are faulty, causing an incorrect load/incorrect switching waveform/frequency, hence the audible whine. They're so cheap, and rather unreliable, I'd try replacing them and see what happens.

Dave

It is possible the electrolytic capacitors on the secondary and/or in the regulation circuit are faulty, causing an incorrect load/incorrect switching waveform/frequency, hence the audible whine. They're so cheap, and rather unreliable, I'd try replacing them and see what happens.

Dave

I think this may be a generic problem with this bit of D-Link equipment.

I bought a DSL-504T a few weeks ago and the whistle is driving me nuts. I don't know what frequency it is, I assume its from the switching supply and I can hear it all round the room. I would put the thing in a padded box but I have needed to see its LEDs several times so its on a shelf noise polluting my environment. BTW I am virtually a senior citizen and its still below my audio cut off frequency.

I bought the modem on line and don't want the hassle of sending it back but I feel that D-Link should have some responsibility here.

Ian Phillips