----- Original Message -----
Sent: Sunday, January 08, 2006 8:15
PM
Subject: RE: [Repeater-Builder] Muffin
Fan speed
John,
Digi-Key and Mouser list both AC and DC fans in many
different speeds, capacities, and sizes. I found a replacement fan for a
Hewlett-Packard signal generator that was form, fit, and function identical to
the original fan- except that the new fan was barely audible. The
original fan was a screamer. The careful design of modern muffin-style
fans allows them to move the same amount of air with much less noise.
Check the dB ratings before you buy.
73, Eric Lemmon WB6FLY
Here's an old idea, that may be worth
repeating:
If you want to run a muffin fan at a slower
speed, to reduce noise and
of course lower the air throughput, put a paper
capacitor in series with
one side of the AC supply.
Recently, my Son-in-Law wanted to cool his stereo
amp
and I used a 2 Mfd 200 volt paper capacitor to
slow the fan down. This value
resulted in about 62 volts feeding the fan and it
run's just fine at that voltage.
Other capacitor values will result in different
voltages which will create
different speed's of the fan
John J. Riddell, VE3AMZ
451 Cedarcliffe
Dr.,
Waterloo, Ontario, Canada
N2K 2J1
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