[mythtv-users] Quiet fans

[Darrin]

On Fri, Oct 17, 2008 at 1:36 AM, Peter Loron <peterl at standingwave.org>wrote:

>
> On Oct 15, 2008, at 5:04 PM, Yan Seiner wrote:
>
> >
> > On Wed, October 15, 2008 4:52 pm, Darrin wrote:
> >
> >> Nice.  If it were me, I'd complicate it a bit more and use an atmel
> >> avr
> >> tiny
> >> to do the same thing.  Then, you have the ability to reprogram it
> >> to your
> >> whims and no potentiometers are needed.  You could even change the
> >> ramp
> >> rate
> >> on the pwm to be completely non-linear for your specific needs. The
> >> ATtiny24
> >> could do the job, has an onboard temp sensor, built in PWM, and
> >> only costs
> >> $1.91 from digi-key.
> >
> > Any chance of doing a project page on this?  That could be cool.
> >
> > Even cooler (no pun intended) would be something with a termistor on a
> > lead that could be stuffed into a hard drive caddy space.  :-)
> >
> > --Yan
> >
>
> Should be quite easy to put together...I've got some Arduino boards
> kicking around. I'd need to get a leaded temp sensor. Hmmm. I wonder
> how expensive it would be to get something together to read K-type
> thermocouples.
>
> -Pete
>

I just ordered parts and picked up a Dallas DS18B20 digital temperature
sensor for less than $5 at Sparkfun electronics.  You could probably call
Dallas and get them to send you a sample if you really want to do it on the
cheap.  I got it mostly to figure out if it would react any faster or better
than the one already on the ATtiny.

Thermocouples would require some added interface circuitry (like the LM741
op-amp) to get a usable signal.  The benefit is that they will detect
temperature changes more quickly than a packaged silicon device would.   I'm
sure there's plenty of example circuits already out there on the web that
would help if you decide to go this route.

--Darrin
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mythtv.org/pipermail/mythtv-users/attachments/20081017/44e0102a/attachment.htm