computer-driven fans II - Page 2

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View
Re: computer-driven fans II
On Mon, 28 Jul 2008 08:53:25 -0400, Rich Webb posted:

Quoted text here. Click to load it
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name56%8-2051-1-ND
Quoted text here. Click to load it
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name49%7-2080-1-ND
Quoted text here. Click to load it
<http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=TMP36GRTZ-REEL7CT-ND>
Quoted text here. Click to load it
<http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=MLX90247-ESF-DSA-ND>
Quoted text here. Click to load it


I think I want 2 sensors near the woodburner.  I can put one in the chimney
I constructed where temps would presumably be near 2000 degrees.  This
would inform the "woodburner is burning" event.  Another would measure the
air temperature near it.  This won't eclipse 85 degrees if the fan is doing
its job.

Would any of the above sensors be better if it were mounted in the metal
trim that goes around the stovepipe as it penetrates my living room
ceiling?  It would be hot to the touch but not so hot as to violate
building codes as far temps near combustibles.  (Everything I've installed
or bought--the stove itself-- is E.P.A. and local building codes approved.)

I have an unnuanced idea of say, how a thermistor would operate.  How would
you know which part of the wire is changing in its resistance?

Quoted text here. Click to load it

Thanks, Rich.  There are so many options that it makes it more difficult to
close in on the very vanilla solution that I'm looking for.

I'll go with digikey.  I tried their chat service and am apprised that I
can call 1 800 DIGIKEY to talk with someone who will help me design this
(during business hrs).

When I get a parts list, I'll broach the topic again, with a more realistic
appraisal of the complexity.
--
When a new source of taxation is found it never means, in practice, that
the old source is abandoned. It merely means that the politicians have two
We've slightly trimmed the long signature. Click to see the full one.
Re: computer-driven fans II

Quoted text here. Click to load it

Bearing in mind that there is rarely exactly one solution to a real
world problem:

The high-temp monitor sounds like a job for a type K thermocouple
married to something like an Analog Devices AD597. That handles much of
the dirty work and can also be configured to provide an "on/off" signal
which could be pretty easily interfaced to a microcontroller.

Quoted text here. Click to load it

That could be a bog-standard thermistor hooked up in a voltage divider
network to a microcontroller's A/D port.

Quoted text here. Click to load it

Probably not, since there would presumably be a considerable time lag.

Quoted text here. Click to load it

For a thermistor, it's not the wire (although the wires will exhibit a
small but negligible resistance change) but the magic stuff inside the
epoxy or glass bead. For a thermocouple, the signal is the voltage
generated by the thermal gradient along the wires; using different
metals for the two wires results in a difference in the voltage gradient
and a measurable voltage difference.

Quoted text here. Click to load it

Sounds like an excellent learning experience!  ;-)

--
Rich Webb     Norfolk, VA

Re: computer-driven fans II
Quoted text here. Click to load it
... snip ...
Quoted text here. Click to load it

Of course not.  All you have to do is tell the cockroach where to
sense the temperature.  This requires a clear knowledge of
cockroach language, together with clear enunciation.  Then you can
take proper advantage of the cockroaches extra-sensory perception.

--
 [mail]: Chuck F (cbfalconer at maineline dot net)
 [page]: <http://cbfalconer.home.att.net
We've slightly trimmed the long signature. Click to see the full one.
Re: computer-driven fans II
On Mon, 28 Jul 2008 14:56:26 -0400, CBFalconer posted:

Quoted text here. Click to load it

This sounds like you're having a little fun with my inexperience.  Fair
enough, I'm attempting to do something ambitious and am a certifiable
neophyte.

The cockroaches here on the Rio Grand are commandos with *amazing*
superhero abilities.  There are so many out on the streets at night that
one can sensibly talk about a cockroach pressure around here.  They have a
meeting with their buddies and then move out in pods.  I think they're
smarter than your average Texans.
--
Unquestionably, there is progress. The average American now pays out twice
as much in taxes as he formerly got in wages. 1
We've slightly trimmed the long signature. Click to see the full one.
Re: computer-driven fans II
Quoted text here. Click to load it

You're right, and maybe I should have softened it.  However your
'cockroach' characterization couldn't be missed.  Many thing can
sense temperature, including mercury thermometers, bimettallic
junctions, diode drops, your fingers, crickets, etc. etc.  In fact,
almost anything.  Even Texans.

--
 [mail]: Chuck F (cbfalconer at maineline dot net)
 [page]: <http://cbfalconer.home.att.net
We've slightly trimmed the long signature. Click to see the full one.
Re: computer-driven fans II
On Wed, 30 Jul 2008 22:11:41 -0400, CBFalconer posted:

Quoted text here. Click to load it

The acronym I learned last night was DIP: dual in-line package.  That's for
these devices with cockroach symmetry.
--
We must be willing to pay a price for freedom. 4
H. L. Mencken

Re: computer-driven fans II

Quoted text here. Click to load it

These devices are called SMD:

http://en.wikipedia.org/wiki/Surface-mount_technology

For prototyping or hobby it is possible to mount them as dead bugs:

http://www.geofex.com/Article_Folders/deadbug/deadbug.htm

Then you can solder the wires more easily.

But sounds like you don't know very much about electronics. Maybe you
should buy a small microcontroller evaluation kit and start with some
basics, like blinking LEDs. You can reuse the kit later for your fan
controller. And if you are not a programmer, maybe you should use something
more simple than an AVR, like this one:

http://www.rev-ed.co.uk/picaxe /

Otherwise you'll need some years until you know all the basics to implement
some C program on a microcontroller, develop a RS485 bus protocol and the
rest of the hardware.

--
Frank Buss, fb@frank-buss.de
http://www.frank-buss.de , http://www.it4-systems.de

Re: computer-driven fans II
On Thu, 31 Jul 2008 04:00:15 +0200, Frank Buss posted:


Quoted text here. Click to load it

I bookmarked this page  (Es ist ja einfacher, englisch zu reden.)  It seems
like it has a lot of stuff for starters.  I've got quite a few items in my
"to buy" list for this project.  Yeah for my rebate check.  It improves
computer science for the hobbyist so much to have a proper budget for it.

--
When a new source of taxation is found it never means, in practice, that
the old source is abandoned. It merely means that the politicians have two
We've slightly trimmed the long signature. Click to see the full one.

Site Timeline