The switched PSU chirps

In the end, although we talked on the phone about returning just the one to check, I did send both back as a comparison of one which I wasn't sure was a problem (Suppose I should be happy my HF hearing is still intact at 40) , and the other which I felt was significantly louder (noiser) which I attached the tape to. Did you not detect any difference between the two smps, one is a flash gun and one 'chirps' for want of a better phrase.

Is/has Fritz returning/ed his yet?

As I said since I returned a smps I wasn't sure about I'm quite happy to stand the postage cost back just PM me the costs.

I think the chirping noise comes more often than not from the ferrite rings in the PSUs. There are two things you can do about this.

Hi FritzS,

We've had the ones back from Serverbaboon plugged-in for near on two weeks now, and admit they do make a noise. But they don't do "chirp, chirp, chirp". Three of us have listened to them at close quarters, aged mid thirties to mid fifties, with keen to average listening abilities, and we can report that they whistle quietly. We've yet to hear them chirping like a canary.

We agree to replacing your SM-PS and will send Serverbaboon two to replace his. I have three plugged in permanently here for my own audio system. If I listen closely to them, yes they do emit a whistling sound, but even in the dead of night, a couple of metres away and nobody here hears them - not even my 9 year old son. I guess if we had a dog it could be different.

My Nokia mobile phone charger does exactly the same. Unlike computer switched-mode supplies, these plug tops work similarly to energy saving light bulbs (which are becoming mandatory in places like Australia) where the frequency of operation is just above the audio spectrum.

The operating frequency lies between 20 and 40 kHz. Components within the plug top will mechanically resonate (even if they're glued down) at such a frequency, just like glass can break with a good female opera singer!

FritzS, I will send you a new tested one, but if that develops the same whistle then I'm sorry - it's simply a fact of life. It's a fact of life brought on by EU, Australian and Californian politicians. If the second one is not to your liking would you please plant it in the cranium of one of the EU instigators? After all, the seat of EU power is easier to get to from Austria than it is from here (by car).

At the end of the day, the "green" Solo was always advertised as a pre-release product pilot sold at a highly discounted price - not a mainstream product, and as such some imperfections are to be expected. To say there are no imperfections like this in the item we make, but just the little power supply, isn't bad? And for a few Euro's it can be cheaply replaced by a linear plug top power supply that doesn't whistle - I'd say you've got a bargain (the emoticon means "hug")


Edited by Graham Slee - 17 Apr 2008 at 8:06am

"hope I haven't come across as a complaining git."

(more big hugs)...

Don't get me wrong - you don't come across as that.

To be perfectly honest, the whole SM-PS thing ****** me off. OK, it'll save the world about 18 power stations of the size of Ferrybridge in West Yorkshire. IMO carbon emissions and their link to "global warming" are a mere diversion - a conjuring trick to disguise the real purpose which is security of supply (as the Eco Design directive partially admits) - in otherwords it's political, and you and I will foot the bill as we usually do.

I could have designed a range of equipment by now, but for RoHS, WEEE and the "rolling" Eco-design directives.

Why do you think I hate politicians? Hope no one here's one!

They get 40 grand a year plus 160 grand expenses and what do they do for it? Yes! They make sure people like you and me don't get anywhere near what they get!

Anarchy? You're b****y well right!