Strange high pitch noise

#1 (**permalink**) 27-10-2006, 03:01 PM

Just plugged my ipaq 4150 into the car via its headphone out socket to twin phono to the back of my head unit (to use TomTom software and play mp3s through car speakers) and there is a loud whistling noise that echos the revs on the car (gets higher pitch the higher the revs) very odd, any ideas why?

Cheers

**Charlie** · #2 (**permalink**) 27-10-2006, 03:49 PM

Its alternator whine. Caused by RF interference from the electrical noise created by the alternator spinning. You can get supressors from auto shops.

#3 (**permalink**) 27-10-2006, 04:12 PM

Thanks for that, forgive my stupidness but what is a supressor and can i fit it myself. Would just a shielded phono lead do the same job?

**Charlie** · #4 (**permalink**) 27-10-2006, 04:47 PM

A supressor is just a device like a ferrite rod/ring that basically soaks up the interference before it gets to your device. They can be fitted quite easily. Halfords stereo department should be able to offer some advice.
A shielded plug may help but I don't think it would stop it completley but is certainly worth a try.