varispeed mod for the fan in my console PSU, any schematics?

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maxime

Well-known member
Joined
May 27, 2005
Messages
156
Location
Brussels, Belgium
hello
I am considering putting a temperature sensor to control the speed of the fan in the PSU of my MXP2000 console. The fan is really overated and noisy ...
This fan is AC powered at 110Volts taken from the psu transformer primary.
Does anyone have some links to schematics?
best wishes to all
and thank you
maxime
 
it's not easy. you'll need a triac or something like that, which also can inject junk into your console. think light dimmers. dunno 'bout PTCs at 110VAC. is it a standard 120mm fan? if so, it would be smarter to replace it with a newer noiseless DC fan with temp control. those temp controls can be bought seperately, but i don't remember seeing any for 110VAC

or maybe just lower the voltage to the fan with a resistor or step down trannie
 
that doesn't cut the fan noise. i think replacing it with a low voltage DC temp controlled fan is the way to go

or go passive. i just passified my computer. what a farkin' bliss
 
It is for 220v but will help i think
http://www.qsl.net/sv3eao/motorcontroler.pdf

Cheers
fotis
 
I would agree, just replace the fan with a "quiet" fan, with built in speed control. Check www.newegg.com Very cheap, and will drop right in.

Micah
 
hi you all
thanks for your advice. The lower wattage dc fan is probably the easiest..
fotis, what a great diy project compiler sheet ! I browse this site quite a bit right now..
bye
maxime
 
I finally found an acceptably noisy 115v fan:
papst 8830N, at RS components.
its noise figure is rating at 21dB(A)
it should be ok...
best
maxime
 
I did a design for a JB_L power amp fan some years ago, in which I derived a sync signal from the fan current and used it in as a tachometer in a feedback control system. The other variable setting the speed was the temperature which was sensed with a N*tional Semi LM35. The fan stopped when the signal fell below a certain level so the fan noise would not be heard.

One of the bits of finesse was that the control loop had a sample-hold, which retained the old control value during music interruption so the thing didn't rev too fast on music resumption. Despite the apparent complexity the cost was low because it used garden-variety op amps and CMOS gates etc., and it sailed into trouble-free production.

I wrote a paper about it but it was only for internal distribution---it was my ticket to a lavish offsite, the cost of which played a major part in getting the then corp. VP of Engineering fired. :sad: In that paper I speculated that if a fan company could just bring out the winding wires the fan could use active electrical braking so that very abrupt interruptions of music could be handled (rather than hear the spindown for a bit).

Not too surprisingly no fan company was interested, since the volumes were not going to be large.
 
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