Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!magnus.acs.ohio-state.edu!csn!ccncsu!purdue!mentor.cc.purdue.edu!noose.ecn.purdue.edu!samsung!cs.utexas.edu!asuvax!mcdphx!qisoff!citek.mcdphx.mot.com!hbg6
From: hbg6@citek.mcdphx.mot.com
Newsgroups: sci.electronics
Subject: Re:Fan for my amp revisited
Message-ID: <12462@qisoff.phx.mcd.mot.com>
Date: 22 Apr 91 15:10:45 GMT
Sender: listen@qisoff.phx.mcd.mot.com
Reply-To: hbg6@citek.mcdphx.mot.com
Organization: Motorola Microcomputer Division, Tempe, Az.
Lines: 22

>ritz@msb.com (Chris Mauritz) writes:
>
>> Someone was kind enough to send me a message saying that controlling
>> the speed of an AC fan was not as simple as adding a pot.  OK,
>> how about I use a DC fan and siphon off power from the power supply
>> for the amp?  The power supply seems to be hefty.  Would there
>> be any danger that a small DC muffin fan would draw enough current
>> to affect the amplifier in any negative way?
>> 

All of the DC muffin fans I have used contain a bunch of digital control
and analog drive circuitry ( tiny SMT parts under the cap at the non-moving
end of the motor ).  This stuff drives a brushless DC motor and probably
would not take kindely to much less than their rated voltage. I'll see if
there is one in our scrap pile to 'smoke' test.

John

.....................................................................
John Schuch - Motorola Inc., Computer Systems Division (602)438-3008
All opinions expressed are mine and not Motorolas,        their loss.
.....................................................................