Wall wart interference

[Brian Gaff (Sofa]

OK so I bought my usual wall warts from Amazon, the sort you plug usb devices in to power them, Unlike usual though these little monsters kick out an incredible amount of rfi on frequencies from long wave to almost 24mhz a kind of grating sawtooth modulated by 50 hz. You cannot get inside, but I'd suggest they have no suppression whatsoever. They still work of course charge up phones power battery chargers and power little gadgets. So I wonder if Amazon would refund me for them? This then leaves me with another issue, I need two or maybe three that do not have this added feature of radio jammer under load. I have tested one from Apple which came with my phone, (but are no longer supplied with phones), and there is really no sign of interference, so it is possible. I guess I could buy from Apple and hope their standards are still high, or if anyone knows of a good source for non interfering ones I'm all ears. Brian

[Andy Burns]

I think amazon basically let you return anything, then they either send it to landfill, or sell it on ias bulk loads of tat.

[Cursitor Doom]

Might be worth winding the leads through a couple of ferrite rings if you have any lying around, Brian. it will never be as good as proper proprietory screeening and filtering, but you might reduce the spatter to an acceptable degree of appalingness.

[Jim GM4DHJ ...]

worst I ever had was a genuine nokia

[Brian Gaff (Sofa]

Well I suspect that the makers are hoodwinking anyone who sells this model. Its sealed so one cannot look inside and no doubt to make it cheaper the high voltage capacitors used to tame the interference have been left out. Bah humbug. Brian

[Brian Gaff (Sofa]

Well the point is that if it was fulfilled by another company, then they have a different process, but all of these came in one parcel from Amazon. I'm more interested in finding a good replacement. Of course the average user would not even realise that this was an issue unless they used one to power an am radio of some sort I guess. Brian

[Brian Gaff (Sofa]

I already did the ferrite ring trick. Indeed I've never found this approach to do very much good at all on noisy psus. I think the sheer wide bandwidth is the issue. Sometimes you can get away with this for medium wave but not much else. I was even thinking of perhaps getting a couple of those power bank batteries as when not actually attached to a charger, they would or should be completely clean and last for an age on the small loads of the gizmos I want to power, but then the battery charger for aaa and aa cells needs to take more current and its bonkers to charge one battery with another!

Brian

[Robin]

[Dave Liquorice]

A decent LC filter might do it. Couple of fairly hefty (to handle the current without too much voltage drop) toridal coils, one in each leg with 0.1uF capacitors across the in and out. Fitted as close as possible to the offending wart should at least stop the power lead radiating crap.

Wouldn't like to bet on it. A Li cell is nominally 3.6V. 5 V power banks use a DC-DC convertor to step up and regulate that 3.6 V to 5 (+/- 0.25 V).

[Chris French]

I've no idea about the interference.

But after a couple of bad expereinces with other USB wallwarts I stick to Anker these days, as they seem a decent .

Of course another possibility is that the 'usual' one you bought were knock-offs hence different pefroamnce?

But you should be abl to geta refund from Amazon ok. Even if purchased from a third party seller due to the their A-Z gurantee thing, IME they tend to ide with the buyer in complaints. We complained about a suitacase (one of a set) that had a small but annoying fault. We complained to the seller to geta replacment or whatever, but they never dealt with it satisfactorily. complained to Amazon, and they refunded the purchase price, and we ened up with free suitcases.

[JohnP]

"Brian Gaff \(Sofa\)" [e-mail]> wrote in news:rrkh0d$6o9$ [e-mail]:

As most people would not be aware of the issue - would it be worth trying to get a recommended wallwart - suggested by an Amateur Radio Group or similar?

[Mike Clarke]

Poundland's USB charger at £2 might be worth a try. Despite the low price Big Clive spoke very highly of it including commenting favourably on the filtering when he did a teardown on YouTube. I appreciate you won't be able to see the video Brian but you might pick up a few details from the audio.

[Martin Brown]

Even Sony are not immune from that aort of mistake. I have a world band radio of theirs and it's official mains adapter generated enough interference to jam it on certain more sensitive long distance SW bands. A clamp on ferrite at each end of the cable made a big difference to it.

A wall wart from the likes or Rapid or RS will cost more but might be a better bet if you care about RF interference. Ask radio hams for recommended model numbers - they are not all created equal.

WOrst one I have seen in a long time was the DC supply for a friends BT answerphone base station which was jamming all mobile phone signals. This only became obvious when it was replaced and the mobile phone signal magically improved at the instant power was removed.

[The Natural Philosopher]

the ones I use (to step *down* from 2+ cells) are used with sensitive radio control receivers. They HAVE to be clean. And they are very cheap. Google UBEC or SBEC.