Advice needed please, FM transmitter interference when power applied to laptop.

moelsaied88 · 08-14-2009, 10:37 PM

Hey guys, im having a problem and im hoping soemone could help me out. im using an fm transmitter to get my sound to my car, i know its the worst possible option but i have literally no other options. anyway, whenever i plug the power adapter into the laptop i get crazy bad static. im not exactly sure what to do. im guessing that its a problem with the ground so i tried putting the negative to the body of the car, but still no fix. is this the type of situation where a ground loop isolator would be the fix? any and all help appreciated, thanks!

PaulF · 08-14-2009, 11:54 PM

what kind of power supply?

moelsaied88 · 08-15-2009, 09:18 AM

its a dc auto-air laptop charger. i got it off of ebay but its been working great so far except for that interference.

pancit175 · 08-15-2009, 02:19 PM

Most power inverters can introduce noise and using the cig plug as a power source doesn't help the situation. If possible, to rule this out, plug in an extension cable to home power and run it towards your car and plug in your computer's power supply. If you still experience the same issue then it is definitely the inverter and power source.

This thread discussion should belong within the power supply or laptop section.

moelsaied88 · 08-15-2009, 06:36 PM

yes it is the charger, but that's why i ask if there's possibly any solution. i put it in the audio because the interference i'm getting is over the sound. does anyone have any ideas of what i can do to fix this? like i said i dont really have any other options beyond the fm transmitter, and i have been thinking of getting a carnetix power supply, its still a bit in the future due to financial reasons. and would a carnetix psu solve this? thanks

trader007 · 08-15-2009, 07:05 PM

have you tried using an in-line fm transmitter? i actually have one i dont use anymore, it plugs right inline to your antenna wire- it cuts way down on the normal static you get with the over-the-air tm transmitters.

moelsaied88 · 08-15-2009, 07:08 PM

i actually did order one, but the seller sent me the wrong item, a plain fm transmitter instead, and claims he didnt, so im in the middle of a dispute now getting it solved. but if the issue is coming from the fact that they are a common power source, would that fix this? like i said its not a problem with the transmitter itself, but the power. i was asking before if a ground loop isolator would fix this, but im not sure if it will.

trader007 · 08-15-2009, 08:10 PM

well i dont think youll ever get rid of all the noise, i never had with FM anything. your radio doesnt even have a cd-changer input or anything that you can mod into a line-in?

moelsaied88 · 08-15-2009, 08:45 PM

nope, nothing i can do with my radio. but how is there nothing i can do? when im charging the computer theres interference over the power line. theres no way i can filter the power or something?

trader007 · 08-15-2009, 09:02 PM

they make power filters... like these it should help at least a little... but any decent power supply made for carpc's should filter power too...

thewizard · 08-16-2009, 03:31 PM

What laptop are you using and what DC voltage does it require? I always had noise issues whenever I tried to run a laptop using an AC-DC adapter and an inverter, but as soon as I found a DC-DC adapter for whatever laptop I was using it was always was clean as a whistle, and this includes the Aspire One that I currently use. The on-board high definition audio in these little laptops produces absolutely incredible sound quality from the line out, although I do run it through a DSP prior to amplification.

moelsaied88 · 08-16-2009, 07:55 PM

im using a dell e1505 which i bileave uses 19.7 volts. im using a direct adapter from the cig light to charge it, not an ac-dc inverter. wats a dsp? prior to this i was using an asus 1000he without any problems, probably because that used a 12 volt charger, so there was no power brick, just a straight wire.

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