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Subject: Re: Getting rid of that damn noise.
From: Rob Ward (
Date: 2001-12-28

If you can hear the whistle with the vol right down, then it is probably a
switching regulator. Ofter the chokes (inductors) on these whistle at maybe
5-10kHz, but as you say, the whistling disappears as the load increases -
this is because the duty cycle (or sometimes frequency) changes as the load
varies. What voltage do you need to drive the HDD? Is it 12V?


----- Original Message -----
From: "Tjerk Schuringa" <>
To: <>
Sent: Friday, December 28, 2001 2:52 AM
Subject: Re: Getting rid of that damn noise.

> I observed two things about the whistle: it is also present with the
volume all
> the way down and it does cease when the HD spins up in my newish (used to
> heehee) unit. I haven't looked at the schematics yet but it could be that
> of the voltage inverters (there must be several!) that feeds the HD goes
into a
> sort of "burst" mode which is about 1 kHz (that irritating whistle) and
goes to
> an ultrasonic frequency when the HD draws current. It's likely to be a
> mod in any case!
> T.J.
> .
> .
> .
> .
> .
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