Skum

I had tons of problems with the generator noise, and had tried a lot of stuff (but apparently gone in the wrong direction). Then finally turning to the net (where I of course should have started) I found this, which works perfectly! Thanks a million man!

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ROMbler

Arg! I just threw away two modems I had kept for the longest time. I have tons of parts that I finally decided to organize and consolidate. The only stuff I chucked were the modems and an 8MB graphics card. I should have known better. I like your tutorial and would have preferred to build the isolator over junking the parts. Never fails when you decide to chuck something

RedGTiVR6

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

some of you should venture into the Car Audio forum more often...

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raxy

sorry to disagree with the solution.

telephone/modem coupling tranformers are good only for telephony,
that mean they are made for telephony bandwidth : 300-4000Hz

below and above this range, nothing is guaranted and the cheaper the device, the narrower its frequency response.

Did you measure 20Khz and 20Hz output levels compared to a reference @ 1KHz ?

spuzzdawg

I might be making a big assumption but I would have thought that the interference noise had a relationship to the RPM of the engine, in which case the telephony bandwidth is almost perfect - I guess it could go a little higher

Spuzzdawg

Rob Withey

The transformers don't filter out the noise. They isolate the grounds.
If it was a case of filtering, a simple high pass RC filter would do the trick.

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Systems retired due to new car

spuzzdawg

Don't know how I forgot it worked by isolating the grounds by the time I got to the end of the thread - thanks for correcting me. A lil OT Rob Withey but how did you get the neat little pop up table for your car specs?

Spuzzdawg

RedGTiVR6

Spuzzdawg -

http://www.mp3car.com/vbulletin/announcements/93477-carpc-specs-user-profile.html#post987518

In the forum announcements.

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MP3Car.com

 

bosstone74

I just grounded my motherboard to the chasis of the car...and it was gone

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BossTone74

raxy

Transformer limited bandwidth means bass end treble will be substracted from your music, this by no means is expected

Virus3000

Thanks, will try this

jasbirriyat

well, i had the same problem with my car pc. i just added a ferrite ring on the RC cable. gave about 3 -4 round around the ring. and the ferrite ring is for about 0.5 usd i think.

Snortonnorton

very impressive that you can build your own.

but a good working GLI is 15 bucks at circuit city made by Tsunami in the car audio section, and it's more durable so I don't have to worry when I shoved it behind my dash.

BiG K

How about this for a poor mans solution to interence??

I bougth a USB creative soundblaster Live, works great etc. But if my phone is near it, with the sound high, it can get alot of interference. So I started experimenting.
I chucked it into a large anti-static bag and hey presto, approx 50% of mobile phone interference gone!

Plastic is not the best thing to wrap things up in and besides, 50% is still quite annoying!

So I wrapped it up in foil.....normal everyday kitchen aluminium foil. Worked a treat, by my reckoning, approx 95% of inteference gone!!

I am willing to bet if I put two layers and grounded the foil, I could possibly get 99% if not possibly 100%??

If it works for mobile phone inteference, could possibly work for other types of inteference??

Since this is a cheap simple way of cutting inteference, maybe someone could put it to use and let us know??

Also, why stop at the sound card? Why not enclose the PSU and/or computer in this manner??

The only problem I can see, with it being aluminium, it conducts electricty, so you have to be VERY careful not to short anything out!

Also could be a tricky issue with vents etc??

altinono

it's work
thinx Gip

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