MP3 Player Charging Whistle

cormie

Hi,
This has been an annoying problem with more than one type of MP3 player I've had, that when I use any type of charger connected to the cigarette adapter, there's a buzzing sound through the speakers, like a little whistle and when you accelerate the whistling gets louder. Even with a USB portable battery charger connected to the cigarette adapter and then the mp3 player connected to the USB charger, it still whistles.

Any ideas how I can stop this, or what to use to stop it would be appreciated

daveharnett

Strange one that. Does it sound anything like mobile phone interference?

EPM

I have this with a car kit when I connect an ipod. Very slight but its there

cormie

Doesn't sound anything like mobile phone interference. I actually saw a usb battery charger being advertised with the feature that it allows charging without the whistle, so it must be a pretty common problem. I didn't order that one, but I ordered one that seemed to be identical, still has the whistle though

polyfusion

I was charging my phone through the cigarette lighter socket today, and noticed a high-pitched whistle, but it's always done it. I've always figured it is just the electronics in the charger (most chargers make some sort of buzz or whine, even indoor ones, if you listen close enough; I think it's common with all types of power inverters/converters).

Never noticed the noise getting louder upon acceleration though. Maybe this has something to do with the condition of your battery, and/or the rate at which it's recharging?

cormie

Same happens with one of my phone chargers in doors alright, this is different though. The whistling is through the stereo, you can't hear it the volume is down. It's definitely related to some kind of interference and not just a regular buzzing anyway

eringobragh

I reread your post:

Sounds like a dodgy ground on the cig lighter or the radio. You could try a ground loop isolator

http://www.mp3car.com/vbulletin/car-audio-faq/79248-induced-noise-ground-loop-trouble-shooting-guide.html

cormie

Thanks again. I'm not so sure about a dodgy ground as I've tried more than one MP3 player charger in 3 different vehicles all with the same buzzing noise. How would you make sure the ground is right though?

cormie

Has anyone got their MP3 player connected and charging in their car without this problem? I have mine connected to AUX in on the head unit by the way I thought this would be a common problem since it's the same in 3 different vehicles I've tested

Pete67

If the pitch of the noise varies in proportion to engine speed its likely to be AC ripple on the 12VDC supply from the alternator. The alternator generates 3phase AC power, which is converted to DC by a 3-phase bridge rectifier built into the alternator itself. Some of the original AC signal remains on the DC line as ripple and may be audible as a whine when used to power small audio devices like FM transmitters or iPods.

The best solution is to filter the DC at the cigarette lighter socket using a suitable capacitor, say an 10,000uF electrolytic capacitor rated at 25V. This will smooth out the ac ripple and leave a clean DC supply. Filters are also available specifically for this purpose, for example this

cormie

:eek: What? hehe that's a lot to take in but thanks a mill for the explanation

You reckon it's that so? What would I do with that thing for $4 exactly? Glad to see a solution may be so cheap anyway

It says about removing it, why would you remove it exactly and why wouldn't something like that come fitted with all cars I wonder? Does it have any negative effect on anything? Would I need to cut open wires and solder it in I wonder?

cormie

Could anyone confirm the above query with the product pete linked to please? I just don't want to risk any damage to anything and would I need to get a solder kit to carry out the install I wonder?

Any feedback appreciated

cormie

If anyone has any idea about the above I'd really appreciate any help

Owen

Should be fine. A simple RC (Resistance Capacitance) filter can be set to remove the whine from your alternator which increases as your engine speed does.

cormie

Thanks for the reply, is that the same thing Pete67 has linked to at the end of his post? How would something like that be fitted? Would I need to solder it and everything I wonder?

cormie

Ordered 3 of the thing above so hopefully it'll sort out the problem I'll probably leave installation to auto electrician because I've got to get a few things sorted that will need auto electrician to make sure they are done right

Victor_M

Is the cigarette lighter you are plugged into a factory fit one or a retro fit? I have seen this a few times with both car handsfree kits and mp3 players. with the hands free power was tapped from the ciggy lighter first and the same symptoms you noticed were evident in my car, I tapped power off the back of the car radio instead and the whine disappeared completely.

With the Dension Icelink for the iPhone, I had to open the connector and swap 2 of the 3 cables around as it was a known issue with some car types, it was a ground loop problem that went away once I followed the walkthrough and swapped the wires around. http://www.dension.com/index.php?pageID=13&articleID=30

cormie

Well the chargers are plugged into the cigarette adaptor on the dash, I'm not sure if that answers your question though

You don't do this for a living and want a few hours work at all I suppose? :cool:

cormie

Just another thing on this which may be connected, when I have the radio on and I use the window washer spray, it produces a hiss on the radio for some reason