Greetings All

I'm looking for a recommendation for a low cost thermocouple DAQ that works with ubuntu linux.
Can someone recommend one. I'm trying to record temperture measurements over time.
tia sal22

On Nov 29, 10:36*am, ratullloch_delthis
wrote:
Greetings All

I'm looking for a recommendation for a low cost thermocouple DAQ that works with ubuntu linux.
Can someone recommend one. *I'm trying to record temperture measurements over time.
tia sal22

How about this...http://www.mccdaq.com/usb-data-acquisition/usb-2001-
tc.aspx

On Nov 29, 10:36*am, ratullloch_delthis
wrote:
Greetings All

I'm looking for a recommendation for a low cost thermocouple DAQ that works with ubuntu linux.
Can someone recommend one. *I'm trying to record temperture measurements over time.
tia sal22

How about this...http://www.mccdaq.com/usb-data-acquisition/usb-2001-
tc.aspx

On Nov 29, 10:36*am, ratullloch_delthis
wrote:
Greetings All

I'm looking for a recommendation for a low cost thermocouple DAQ that works with ubuntu linux.
Can someone recommend one. *I'm trying to record temperture measurements over time.
tia sal22

http://www.mccdaq.com/usb-data-acqui...b-2001-tc.aspx

On Nov 29, 10:36*am, ratullloch_delthis
wrote:
Greetings All

I'm looking for a recommendation for a low cost thermocouple DAQ that works with ubuntu linux.
Can someone recommend one. *I'm trying to record temperture measurements over time.
tia sal22

How about this...
http://www.mccdaq.com/usb-data-acqui...b-2001-tc.aspx

On Mon, 29 Nov 2010 16:36:56 +0000, ratullloch_delthis wrote:

Greetings All

I'm looking for a recommendation for a low cost thermocouple DAQ that
works with ubuntu linux. Can someone recommend one. I'm trying to
record temperture measurements over time. tia sal22

http://www.mccdaq.com/daq-software/Linux-Support.aspx

Single channel thermocouple to USB with linux support $99, multiple
channels more $.

On 10-11-29 03:32 PM, Glen Walpert wrote:
On Mon, 29 Nov 2010 16:36:56 +0000, ratullloch_delthis wrote:

Greetings All

I'm looking for a recommendation for a low cost thermocouple DAQ that
works with ubuntu linux. Can someone recommend one. I'm trying to
record temperture measurements over time. tia sal22

http://www.mccdaq.com/daq-software/Linux-Support.aspx

Single channel thermocouple to USB with linux support $99, multiple
channels more $.


Arduino, USB, minimum 6 analog inputs, Linux support, 37 dollars to
start, then 6 bucks max for additional microcontrollers.



mike

Glen Walpert wrote:
On Mon, 29 Nov 2010 16:36:56 +0000, ratullloch_delthis wrote:

Greetings All

I'm looking for a recommendation for a low cost thermocouple DAQ that
works with ubuntu linux. Can someone recommend one. I'm trying to
record temperture measurements over time. tia sal22

http://www.mccdaq.com/daq-software/Linux-Support.aspx

Single channel thermocouple to USB with linux support $99, multiple
channels more $.

Thermocouples are really really horrible temperature sensors--almost as
bad as ICs. Their advantages are small size, relatively low cost, and
(potentially) high speed, but their disadvantage is that it's really
hard to get good measurements.

One reason for this is thermal conduction down the leads (which is a big
problem for most temperature sensors). There's a worse one, though:
due to their very low sensitivity, thermocouples are extremely
vulnerable to errors caused by offset drift in the circuitry. See
Figure 20.3 on P. 803 at http://electrooptical.net/www/book/draftthermal.pdf

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058

email: hobbs (atsign) electrooptical (period) net
http://electrooptical.net

On Tue, 30 Nov 2010 13:11:18 -0500, Phil Hobbs
wrote:

Glen Walpert wrote:
On Mon, 29 Nov 2010 16:36:56 +0000, ratullloch_delthis wrote:

Greetings All

I'm looking for a recommendation for a low cost thermocouple DAQ that
works with ubuntu linux. Can someone recommend one. I'm trying to
record temperture measurements over time. tia sal22

http://www.mccdaq.com/daq-software/Linux-Support.aspx

Single channel thermocouple to USB with linux support $99, multiple
channels more $.

Thermocouples are really really horrible temperature sensors--almost as
bad as ICs. Their advantages are small size, relatively low cost, and
(potentially) high speed, but their disadvantage is that it's really
hard to get good measurements.

One reason for this is thermal conduction down the leads (which is a big
problem for most temperature sensors). There's a worse one, though:
due to their very low sensitivity, thermocouples are extremely
vulnerable to errors caused by offset drift in the circuitry. See
Figure 20.3 on P. 803 at http://electrooptical.net/www/book/draftthermal.pdf

"Thermocouples generate a voltage related to the temperature difference
between two junctions of dissimilar metal wires, and are a pain in the
neck. ... For less specialized applications, avoid thermocouples
like fleas."

Okay, now I'm going to *have* to buy that book!

--
Rich Webb Norfolk, VA

Op 30-11-2010 20:15, Rich Webb schreef:
On Tue, 30 Nov 2010 13:11:18 -0500, Phil Hobbs
wrote:

Glen Walpert wrote:
On Mon, 29 Nov 2010 16:36:56 +0000, ratullloch_delthis wrote:

Greetings All

I'm looking for a recommendation for a low cost thermocouple DAQ that
works with ubuntu linux. Can someone recommend one. I'm trying to
record temperture measurements over time. tia sal22

http://www.mccdaq.com/daq-software/Linux-Support.aspx

Single channel thermocouple to USB with linux support $99, multiple
channels more $.

Thermocouples are really really horrible temperature sensors--almost as
bad as ICs. Their advantages are small size, relatively low cost, and
(potentially) high speed, but their disadvantage is that it's really
hard to get good measurements.

One reason for this is thermal conduction down the leads (which is a big
problem for most temperature sensors). There's a worse one, though:
due to their very low sensitivity, thermocouples are extremely
vulnerable to errors caused by offset drift in the circuitry. See
Figure 20.3 on P. 803 at http://electrooptical.net/www/book/draftthermal.pdf

"Thermocouples generate a voltage related to the temperature difference
between two junctions of dissimilar metal wires, and are a pain in the
neck. ... For less specialized applications, avoid thermocouples
like fleas."

Okay, now I'm going to *have* to buy that book!


Thermocouples are very linear and can messure upto 2320 degrees celsius.

Nice table in the dutch wiki page.
https://secure.wikimedia.org/wikipedia/nl/wiki/Thermokoppel

--
pim.

tuinkabouter wrote:
Op 30-11-2010 20:15, Rich Webb schreef:
On Tue, 30 Nov 2010 13:11:18 -0500, Phil Hobbs
wrote:

Glen Walpert wrote:
On Mon, 29 Nov 2010 16:36:56 +0000, ratullloch_delthis wrote:

Greetings All

I'm looking for a recommendation for a low cost thermocouple DAQ that
works with ubuntu linux. Can someone recommend one. I'm trying to
record temperture measurements over time. tia sal22

http://www.mccdaq.com/daq-software/Linux-Support.aspx

Single channel thermocouple to USB with linux support $99, multiple
channels more $.

Thermocouples are really really horrible temperature sensors--almost as
bad as ICs. Their advantages are small size, relatively low cost, and
(potentially) high speed, but their disadvantage is that it's really
hard to get good measurements.

One reason for this is thermal conduction down the leads (which is a big
problem for most temperature sensors). There's a worse one, though:
due to their very low sensitivity, thermocouples are extremely
vulnerable to errors caused by offset drift in the circuitry. See
Figure 20.3 on P. 803 at
http://electrooptical.net/www/book/draftthermal.pdf

"Thermocouples generate a voltage related to the temperature difference
between two junctions of dissimilar metal wires, and are a pain in the
neck. ... For less specialized applications, avoid thermocouples
like fleas."

Okay, now I'm going to *have* to buy that book!


Thermocouples are very linear and can messure upto 2320 degrees celsius.

Nice table in the dutch wiki page.
https://secure.wikimedia.org/wikipedia/nl/wiki/Thermokoppel


"Nice and linear" is in the eye of the beholder. They're a lot better
than thermistors, that's for sure.

And up in the orange-hot region you probably don't care if you're off by
a couple of degrees, but down near room temperature you usually do.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058

email: hobbs (atsign) electrooptical (period) net
http://electrooptical.net

On Tue, 30 Nov 2010 14:15:28 -0500, Rich Webb wrote:

On Tue, 30 Nov 2010 13:11:18 -0500, Phil Hobbs
wrote:

Glen Walpert wrote:
On Mon, 29 Nov 2010 16:36:56 +0000, ratullloch_delthis wrote:

Greetings All

I'm looking for a recommendation for a low cost thermocouple DAQ that
works with ubuntu linux. Can someone recommend one. I'm trying to
record temperture measurements over time. tia sal22

http://www.mccdaq.com/daq-software/Linux-Support.aspx

Single channel thermocouple to USB with linux support $99, multiple
channels more $.

Thermocouples are really really horrible temperature sensors--almost as
bad as ICs. Their advantages are small size, relatively low cost, and
(potentially) high speed, but their disadvantage is that it's really
hard to get good measurements.

One reason for this is thermal conduction down the leads (which is a big
problem for most temperature sensors). There's a worse one, though: due
to their very low sensitivity, thermocouples are extremely vulnerable to
errors caused by offset drift in the circuitry. See Figure 20.3 on P.
803 at http://electrooptical.net/www/book/draftthermal.pdf

"Thermocouples generate a voltage related to the temperature difference
between two junctions of dissimilar metal wires, and are a pain in the
neck. ... For less specialized applications, avoid thermocouples like
fleas."

Okay, now I'm going to *have* to buy that book!

Yes, that is a good one, and I can't argue with Phil's assessment of TC
accuracy, but "You can learn all you ever wanted to know about them from
the Omega Engineering catalogue." is true only if you have no interest in
how they actually work (as opposed to how to use them) or how to make a
really good low drift TC measurement system with accurate CJC and high
immunity to EMI, for instance.

There are many trade-offs in sensor selection, and thermocouples excel in
temperature range and durability as well as (sometimes) speed. A TC can
be smashed flat with a hammer and suffer no loss in accuracy until the
wires break, or welded to metal parts for excellent thermal contact with
the part being measured, for instance. Try that with a thermistor :-).

Glen Walpert wrote:
On Tue, 30 Nov 2010 14:15:28 -0500, Rich Webb wrote:

On Tue, 30 Nov 2010 13:11:18 -0500, Phil Hobbs
wrote:

Glen Walpert wrote:
On Mon, 29 Nov 2010 16:36:56 +0000, ratullloch_delthis wrote:

Greetings All

I'm looking for a recommendation for a low cost thermocouple DAQ that
works with ubuntu linux. Can someone recommend one. I'm trying to
record temperture measurements over time. tia sal22

http://www.mccdaq.com/daq-software/Linux-Support.aspx

Single channel thermocouple to USB with linux support $99, multiple
channels more $.

Thermocouples are really really horrible temperature sensors--almost as
bad as ICs. Their advantages are small size, relatively low cost, and
(potentially) high speed, but their disadvantage is that it's really
hard to get good measurements.

One reason for this is thermal conduction down the leads (which is a big
problem for most temperature sensors). There's a worse one, though: due
to their very low sensitivity, thermocouples are extremely vulnerable to
errors caused by offset drift in the circuitry. See Figure 20.3 on P.
803 at http://electrooptical.net/www/book/draftthermal.pdf

"Thermocouples generate a voltage related to the temperature difference
between two junctions of dissimilar metal wires, and are a pain in the
neck. ... For less specialized applications, avoid thermocouples like
fleas."

Okay, now I'm going to *have* to buy that book!

Yes, that is a good one, and I can't argue with Phil's assessment of TC
accuracy, but "You can learn all you ever wanted to know about them from
the Omega Engineering catalogue." is true only if you have no interest in
how they actually work (as opposed to how to use them) or how to make a
really good low drift TC measurement system with accurate CJC and high
immunity to EMI, for instance.

There are many trade-offs in sensor selection, and thermocouples excel in
temperature range and durability as well as (sometimes) speed. A TC can
be smashed flat with a hammer and suffer no loss in accuracy until the
wires break, or welded to metal parts for excellent thermal contact with
the part being measured, for instance. Try that with a thermistor :-).


You can solder RTDs down, which is about the same thing. And the
circuit details aren't really information about the _sensor_--any
sufficiently poor sensor will have those problems.

I've used thermocouples reasonably often, generally running inside an
evaporator or someplace like that, and attached to a Fluke thermocouple
thermometer with built-in cold junction compensation. That was probably
good to a couple of degrees, which was all I really needed, especially
since I didn't have to replace the TCs, so the measurements correlated
pretty well over time.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058

email: hobbs (atsign) electrooptical (period) net
http://electrooptical.net

On Tue, 30 Nov 2010 13:11:18 -0500, Phil Hobbs
wrote:

Glen Walpert wrote:
On Mon, 29 Nov 2010 16:36:56 +0000, ratullloch_delthis wrote:

Greetings All

I'm looking for a recommendation for a low cost thermocouple DAQ that
works with ubuntu linux. Can someone recommend one. I'm trying to
record temperture measurements over time. tia sal22

http://www.mccdaq.com/daq-software/Linux-Support.aspx

Single channel thermocouple to USB with linux support $99, multiple
channels more $.

Thermocouples are really really horrible temperature sensors--almost as
bad as ICs. Their advantages are small size, relatively low cost, and
(potentially) high speed, but their disadvantage is that it's really
hard to get good measurements.

One reason for this is thermal conduction down the leads (which is a big
problem for most temperature sensors). There's a worse one, though:
due to their very low sensitivity, thermocouples are extremely
vulnerable to errors caused by offset drift in the circuitry. See
Figure 20.3 on P. 803 at http://electrooptical.net/www/book/draftthermal.pdf

Not to mention that they involve a reference junction for
which you must know the temperature. Unless you have an ice
bath handy, this involves an independent non-thermocouple
sensor like a thermistor, diode, or IC. So just use that
instead! (Unless you need really high temperatures.)

One good thing about TCs is that they don't need typically
calibration... they are supposed to conform to a standard
for the TC type (J, K, R, S etc). You just measure the
output voltage, correct for the reference junction
temperature, and look up the temperature for that voltage.
Accuracy is typically +/-2 degrees C. But the voltages are
really small: 1 mv or less at room temperature (0.10 mV
for R or S types).

I'd say, save the thermocouples for the really hot stuff.
For "normal" temperatures (say, freezing to boiling water
ranges), you can get much better precision and accuracy, not
to mention convenience, from an IC.

Best regards,





Bob Masta

DAQARTA v5.10
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, FREE Signal Generator
Pitch Track, Pitch-to-MIDI
DaqMusic - FREE MUSIC, Forever!
(Some assembly required)
Science (and fun!) with your sound card!

Bob Masta wrote:
On Tue, 30 Nov 2010 13:11:18 -0500, Phil Hobbs
wrote:

Glen Walpert wrote:
On Mon, 29 Nov 2010 16:36:56 +0000, ratullloch_delthis wrote:

Greetings All

I'm looking for a recommendation for a low cost thermocouple DAQ that
works with ubuntu linux. Can someone recommend one. I'm trying to
record temperture measurements over time. tia sal22

http://www.mccdaq.com/daq-software/Linux-Support.aspx

Single channel thermocouple to USB with linux support $99, multiple
channels more $.

Thermocouples are really really horrible temperature sensors--almost as
bad as ICs. Their advantages are small size, relatively low cost, and
(potentially) high speed, but their disadvantage is that it's really
hard to get good measurements.

One reason for this is thermal conduction down the leads (which is a big
problem for most temperature sensors). There's a worse one, though:
due to their very low sensitivity, thermocouples are extremely
vulnerable to errors caused by offset drift in the circuitry. See
Figure 20.3 on P. 803 at http://electrooptical.net/www/book/draftthermal.pdf

Not to mention that they involve a reference junction for
which you must know the temperature. Unless you have an ice
bath handy, this involves an independent non-thermocouple
sensor like a thermistor, diode, or IC. So just use that
instead! (Unless you need really high temperatures.)

One good thing about TCs is that they don't need typically
calibration... they are supposed to conform to a standard
for the TC type (J, K, R, S etc). You just measure the
output voltage, correct for the reference junction
temperature, and look up the temperature for that voltage.
Accuracy is typically +/-2 degrees C. But the voltages are
really small: 1 mv or less at room temperature (0.10 mV
for R or S types).

I'd say, save the thermocouples for the really hot stuff.
For "normal" temperatures (say, freezing to boiling water
ranges), you can get much better precision and accuracy, not
to mention convenience, from an IC.

If all you need is a degree or two's accuracy near room temperature,
almost any method will work. IC temperature sensors are generally
fairly putrid--slow, inaccurate, and noisy.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058

email: hobbs (atsign) electrooptical (period) net
http://electrooptical.net

On Wed, 01 Dec 2010 20:24:09 -0500, Phil Hobbs
wrote:

Bob Masta wrote:
On Tue, 30 Nov 2010 13:11:18 -0500, Phil Hobbs
wrote:

Glen Walpert wrote:
On Mon, 29 Nov 2010 16:36:56 +0000, ratullloch_delthis wrote:

Greetings All

I'm looking for a recommendation for a low cost thermocouple DAQ that
works with ubuntu linux. Can someone recommend one. I'm trying to
record temperture measurements over time. tia sal22

http://www.mccdaq.com/daq-software/Linux-Support.aspx

Single channel thermocouple to USB with linux support $99, multiple
channels more $.

Thermocouples are really really horrible temperature sensors--almost as
bad as ICs. Their advantages are small size, relatively low cost, and
(potentially) high speed, but their disadvantage is that it's really
hard to get good measurements.

One reason for this is thermal conduction down the leads (which is a big
problem for most temperature sensors). There's a worse one, though:
due to their very low sensitivity, thermocouples are extremely
vulnerable to errors caused by offset drift in the circuitry. See
Figure 20.3 on P. 803 at http://electrooptical.net/www/book/draftthermal.pdf

Not to mention that they involve a reference junction for
which you must know the temperature. Unless you have an ice
bath handy, this involves an independent non-thermocouple
sensor like a thermistor, diode, or IC. So just use that
instead! (Unless you need really high temperatures.)

One good thing about TCs is that they don't need typically
calibration... they are supposed to conform to a standard
for the TC type (J, K, R, S etc). You just measure the
output voltage, correct for the reference junction
temperature, and look up the temperature for that voltage.
Accuracy is typically +/-2 degrees C. But the voltages are
really small: 1 mv or less at room temperature (0.10 mV
for R or S types).

I'd say, save the thermocouples for the really hot stuff.
For "normal" temperatures (say, freezing to boiling water
ranges), you can get much better precision and accuracy, not
to mention convenience, from an IC.

If all you need is a degree or two's accuracy near room temperature,
almost any method will work. IC temperature sensors are generally
fairly putrid--slow, inaccurate, and noisy.

Cheers

Phil Hobbs


Resistor bolometer 2 mm sq, 2 mm behind probably a Ge window (in a
little to-39 pkg) at whatever needed distance behind a half inch diameter
plastic Fresnel lens with some nice read circuitry and LCD display with
read and hold mode, etc., and a little laser focal point spotter.

Pretty damned good accuracy from every test I could put it through,
from new batteries, all the way down to both cells being dead... the
damned thing reads. (obviously the data cell is not completely dead at
that point)

$20 at Harbor Freight.

http://www.harborfreight.com/infrare...ter-93984.html

On Mon, 29 Nov 2010 16:36:56 GMT, ratullloch_delthis
wrote:

Greetings All

I'm looking for a recommendation for a low cost thermocouple DAQ that works with ubuntu linux.
Can someone recommend one. I'm trying to record temperture measurements over time.
tia sal22


I can't help with the Linux part, but maybe you can use some
circuits I developed for my Windows-based Daqarta system.
There is a simple temperature to frequency converter at
http://www.daqarta.com/dw_kkee.htm. It uses an LM335
temperature sensor plus an LM331 V-F, powered from a 9V
battery.

Besides the schematic and design formulas, there is a link
there to a printable board layout if you want to roll your
own. There is also a link to an ExpressPCB board layout
that you can modify and/or submit to ExpressPCB to have them
make the boards. (I have no connection to ExpressPCB, but
their software seems to have an easy learning curve, and is
free for non-commercial use.)

Note that all this assumes you have Linux software that can
measure frequencies. (Daqarta does that in Windows, plus
provides calibration for direct temperature readout in C or
F, including negative readings.)

Best regards,


Bob Masta

DAQARTA v5.10
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, FREE Signal Generator
Pitch Track, Pitch-to-MIDI
DaqMusic - FREE MUSIC, Forever!
(Some assembly required)
Science (and fun!) with your sound card!

On 11/29/2010 10:36 AM, ratullloch_delthis wrote:
Greetings All

I'm looking for a recommendation for a low cost thermocouple DAQ that works with ubuntu linux.
Can someone recommend one. I'm trying to record temperture measurements over time.
tia sal22


Do you really have to use thermocouples? They are the hardest way to
measure temperature. I prever the Analog Devices AD590 series, I think
there is also a plastic-package version, the AD592. They are a
2-terminal sensor, where current is proportional to absolute
temperature. So, room temperature is 20 C or 293 K, so it conducts a
current of 29.3 uA.

Jon

On Tue, 30 Nov 2010 17:38:20 -0600, Jon Elson wrote:

On 11/29/2010 10:36 AM, ratullloch_delthis wrote:
Greetings All

I'm looking for a recommendation for a low cost thermocouple DAQ that works with ubuntu linux.
Can someone recommend one. I'm trying to record temperture measurements over time.
tia sal22


Do you really have to use thermocouples? They are the hardest way to
measure temperature. I prever the Analog Devices AD590 series, I think
there is also a plastic-package version, the AD592. They are a
2-terminal sensor, where current is proportional to absolute
temperature. So, room temperature is 20 C or 293 K, so it conducts a
current of 29.3 uA.

Jon

They can have long soak times, lengthening response time. If that is a
factor.

IR is much faster and just as accurate and repeatable, and especially
so if the usage is meant to look at the same target constantly.

Why folks shy away from IR thermometry is beyond me.

On Mon, 29 Nov 2010 16:36:56 GMT, ratullloch_delthis
wrote:

Greetings All

I'm looking for a recommendation for a low cost thermocouple DAQ that works with ubuntu linux.
Can someone recommend one. I'm trying to record temperture measurements over time.
tia sal22


Here is one way...

http://www.linuxjournal.com/article/10809?page=0,0

Another is to buy a cheap $30 Harbor Freight multimeter that has a
serial or USB port on it, and then hack at the output streams from within
Ubuntu, if there is no actual Linux app.

Usually, there are only windows applets for that stuff, but you could
run that in a window within Ubuntu as well. If DOS applets are available,
you could then simply use DOSBox, if it can see the serial or USB
ports.