Archived from groups: alt.comp.hardware.homebuilt (
More info?)
On Wed, 21 Apr 2004 06:23:20 -0700, willy@chilly.com wrote:
>
>I picked up an Antec 120mm "SmartCool" fan that has a blue thermistor
>sticking out of the hub that varies the speed of the fan depending on
>how hot it is.
>
>I want to use this fan at full speed all the time.
>
>I was wondering if anyone knows if you short the leads, clip the
>thermistor off, or if you just can't mess with it.
>
>
You can short the leads of the thermistor to accomplish that, it is by far
the easiest way to do it. However you may want to try shorting the leads
by simply touching a piece of metal to them first, to see how fast it'll
be going, as the resulting RPM is probably higher than you'd expect, might
be too loud for your tastes... typically no system needs a 120mm fan at
maximum possible RPM. If the system is large enough to hold THAT many
devices generating heat there should be room *somewhere* for more fans.
On the other hand, an alternative could be to replace the thermistor with
a variable POT, perhaps a 5K or 10K Ohm, but since you want highest RPM
that's not necessary. Another alternative could be to attach a second
thermistor in parallel with the first. The result would be a higher
initial RPM, and it's [RPM to temp rise] response would be higher, even
further RPM increase.
Clipping the thermistor off would result in lowest possible RPM, and
possibly a distracting "pulsing" sound because there's typically two
resistors controlling the fan speed, and too great an imbalance with the
thermistor completely disconnected. You can't easily access the 2nd
resistor, would require completely disassembling the fan and in some
cases, it would be distructive because it may be mounted on the back side
of the PCB which is air/friction assembled and not removable for all
practical purposes.
You might consider that the Antec Smartcool is a premium-priced fan, but
not any better quality than any major name-brand. Typically costing $15
or more, it might seem as cost-effective to keep that fan "as-is" and buy
a single-speed fan, which might cost only $5 at some of the various online
electronics surplus 'sites, and would also give you a better choice of the
fixed single-speed without having to buy and attach a POT.
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