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Hello

It seems that have an elektrical problem. Maybe someone can help or give hints:

I own a Renault Megane I 1.16 16V Break (Year 2000). I have a Tablet-PC (Android) which I use for navigation. As internal speakers of the tablet are bad, I connected some external speakers to the tablet (via audiocable). the external speakers are getting power over USB-cabel connected to the lighter-plug with an adapter. Tablet is also connected via USB-adapter to the lighter-plug (for loading battery). So far everything works fine, but if the USB-cabel for loading the tablets battery is plugged in, I have noise on the external speakers and in a certain timeloop I can also hear a CLICK in the external speakers. As soon as I unplug the loading USB-cable the noise disappears and also the clicking. I tried different USB-adapters and also other external boxes and different USB-cables and audiocables. always the same result.

If I connect a power-inverter to a second lighter-plug which converts 12V DC to 220V AC and there I plugin a 220V AC/DC-Converter with USB-output where I take the power to the external boxes, no noise and clicking. I also tried to connect a second lighter-Plug with USB-Port to the cabin-light-power and tried to connect power for the speakers there - same issue.

Do I have an elektrical problem in my Renault, or could the problem be in the tablet? Otherwise - why is it working with the power-inverter in between?

By the way: It also works perfect with no noise and clicking, if I take the power for the speakers from an AC/DC-Adapter plugged in outside the car from the 220V in my garage.

Maybe someone can explain me the problem, or has a solution?

The problem exists if i only turn on ignition (12V) or if engine is running (14.4V)

Greetings
Mitch
 

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Technical Supremo, Platinum, I let the Dogs out
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Re: Noise in Speakers connected to Lighter (USB)

like some mobile phones the charging system of your tablet gives off a lot of electromagnetic crap when in operation from a cars charging system, as your speakers are connected to the tablet, which internally is connected to the charging mechanism ( as the speakes draw power from it), they could be sensitive enough to pick up this EM crap whilst charging off a cars electical system, you could always try and find a USB cable with these fitted - Ferrit Bead - they helped me when my DAB radio lost signal when I was charging my phone
 

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Re: Noise in Speakers connected to Lighter (USB)

Thanks for the hint. It works now. just using a ferrit beaded micro-usb cable did not solve the problem, but using a "normal" A-B usb-cable (from a printer) with two ferrit beads connected to a little unpowered usb-hub and then plugging the micro-usb to this and go to the tablet - this solved the problem. At least I don't waste no power anymore for the 12/220V inverter. :D
 

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Technical Supremo, Platinum, I let the Dogs out
Joined
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7,237 Posts
Re: Noise in Speakers connected to Lighter (USB)

Thanks for the hint. It works now. just using a ferrit beaded micro-usb cable did not solve the problem, but using a "normal" A-B usb-cable (from a printer) with two ferrit beads connected to a little unpowered usb-hub and then plugging the micro-usb to this and go to the tablet - this solved the problem. At least I don't waste no power anymore for the 12/220V inverter. :D

a little convoluted, but at least it works for you :grin2:
 

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