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what type of probe is this? e.g. K-Type e.t.c.

I would like to get a temperature probe like this, from an electronics
place.

How would it be described technically? I know they have specific
names, for the form of the bit at the end. K-Type e.t.c.

Here is a picture (it is measuring a HDD temp)
http://www.overclockersclub.com/reviews/nzxt_sentry/images/12.htm

I am also interested in the same question, regarding this probe.
It is measuring CPU temp
http://www.overclockersclub.com/reviews/nzxt_sentry/images/9.htm

Note- I know there are other ways. Software, IR Temp sensor Gun, to
measure temp of components. But I am interested particularly, in these
temp probes like in the picture. some wires and a thing on the end,
and you tape it to the component and read the temperature.

Thanks.
 
B

BobG

Jan 1, 1970
0
You dont need a Type K thermocouple until you get in the 100s of
degrees... like for exhaust temperature but a max6675 thermocouple
preamp lets you read 0-1023 deg c on an SPI interface. An IC like an
LM35 puts out 10mv per degree C, has 3 wires, read with an a/d input.
A maxim DS18B20 reads 16th degrees C on a 2 wire digital bus. There
are Positive Temperature Coefficient and Negative TC thermistors that
are accurate but nonlinear and need the correct bias resistor to
prevent self heating. Read with a/d input. Phew. Lots of choices.
 
You dont need a Type K thermocouple until you get in the 100s of
degrees... like for exhaust temperature but a max6675 thermocouple
preamp lets you read 0-1023 deg c on an SPI interface. An IC like an
LM35 puts out 10mv per degree C, has 3 wires, read with an a/d input.
A maxim DS18B20 reads 16th degrees C on a 2 wire digital bus. There
are Positive Temperature Coefficient and Negative TC thermistors that
are accurate but nonlinear and need the correct bias resistor to
prevent self heating. Read with a/d input. Phew. Lots of choices.

Forget I said K-Type Thermoprobe

What is the type of probe that is in that picture, measuring the
temperature of that hard drive?

(As in physically. And as far as temp sensing range is concerned, I
am interested in 0-100C)
 
P

Phil Allison

Jan 1, 1970
0
<[email protected]
Forget I said K-Type Thermoprobe

What is the type of probe that is in that picture, measuring the
temperature of that hard drive?


** Impossible to tell - that pic is far from clear enough and there is
nothing distinctive about what you can see.

My bet is that it is a simple thermistor or maybe just a diode & not a
"thermocouple" at all.



...... Phil
 
<[email protected]





** Impossible to tell  -  that pic is far from clear enough and there is
nothing distinctive about what you can see.

My bet is that it is a simple thermistor or maybe just a diode & not a
"thermocouple"  at all.

.....  Phil

ok..
note- that word thermocouple only slipped accidentally. BobG
mentioned it, and it stuck in my head when writing my post!

I guess the name for the type of ending that probe has, is unknown..
And maybe it isn't even that significant. Maybe a bead type ending
would be fine.

I spoke to a brilliant electronics guy.. he couldn't give me a name
for the shape of the thing at the end of it. I guess a flat U
shape! looks better contact than a bead.

He mentioned to me that a
Thermistor - measures resistance
Thermocouple - measures voltage

and they have tables that show resistance or voltage. compared to
temperature.

It can do 0-100C

I have a bead thermister somewhere.

http://www.maplin.co.uk/module.aspx?ITAG=SPEC&ModuleNo=2218&doy=14m2#spec
maplin number FX21 i think

Apparently, it's non-linear (NTC my electronics friend said) So I
won't bother trying to plot it on a graph myself(like with hot water
and ice). I will use a table/graph it comes with.. The maplin guy sent
me a pdf with that data.

Apparently there are devices with LED screens and wires to a
thermistor.

Digital Multimeters with a bead thermister, or one that plugs in.
Though that is effectively the same.

Though the devices with LED screens and wires to a thermister, would
probably have a chip to convert it to Degrees C.


Since I am measuring temp of a hdd in an enclosure,
I asked my electronics friend (I talked to in a chat - on IRC ) I
asked him if a long wire would cause any problem..
The electronics guy said it was fine and was sure that even a 30cm
thin wire would cause a negligible resistance difference compared to
the error within the thermistor itself. I said wire would be as thin
as the wire that connects PC Speaker to connector to jumper within
computer. He said that's 24AWG he reckoned.

I seem to remember crocodile clips getting bad contact.. And I recall
different contact between wire and legs of thermistor, causing
different resistance.
He said that croc clips would be fine though

Though I will be using < 30cm thin wires.. He confirmed my suggestion
that it's fine to wind them round the legs. and tape them with
insulation tape

So. I guess i'll look back into this..

But may get that device anyway.. then I can test my thermistor usage
skills!
Will test it with a thermometer in water compared to "my thermistor"
in water too.
 
E

Eeyore

Jan 1, 1970
0
Phil said:
"BobG" <


** Not true.

K-type thermocouples are ideal for many applications over a very wide temp
range - mainly due to the tiny thermal mass and size of the bead that has
to be heated (or cooled).

Perfect for small semiconductors, heatsinks and inaccessible spots.

In any case, most K probes are sold with Teflon coated lead wires and so are
only safe up to 250 C max.

I agree 100%.

Furthermore, there are many quite inexpensive DMMs with K-type inputs. A K-type
thermocouple is the simplest to use for the non-expert who doesn't want to get
involved in all the fuss with different themocouple materials.

One small point. K-type connectors used to be colour coded yellow. It seems to
have changed to green now for some daft reason. They are compatible though.

Graham
 
I agree 100%.

Furthermore, there are many quite inexpensive DMMs with K-type inputs. A K-type
thermocouple is the simplest to use for the non-expert who doesn't want toget
involved in all the fuss with different themocouple materials.

One small point. K-type connectors used to be colour coded yellow. It seems to
have changed to green now for some daft reason. They are compatible though..

Graham-

I see, K-Type refers to the power end, not the sensing end , which was
what I was wondering about.

I will get a DMM with a K-Type socket .. And a K-Type thermistor to
match.

Regarding material for the thermocouple. My friend did mention that a
thermocouple uses 2 different metals, to get a difference in voltage.
But a)I will be using a thermistor anyway b)I just ask the electronics
store for one that goes 0-100C , and a table. That's the
functionality, so the implemenetation - if there are differences ,
makes no difference to me.

If for example I don't get a K-Type plug DMM and K-Type Thermistor.
Are there then any issues with wrapping wire around the legs of a bead
thermistor, tying them to it with insulation tape, and connecting them
to a DMM with crocodile clips?


Thanks
 
P

Phil Allison

Jan 1, 1970
0
<[email protected]>

I see, K-Type refers to the power end, not the sensing end , which was
what I was wondering about.

I will get a DMM with a K-Type socket .. And a K-Type thermistor to
match.

Regarding material for the thermocouple. My friend did mention that a
thermocouple uses 2 different metals, to get a difference in voltage.
But a)I will be using a thermistor anyway b)I just ask the electronics
store for one that goes 0-100C , and a table. That's the
functionality, so the implemenetation - if there are differences ,
makes no difference to me.

If for example I don't get a K-Type plug DMM and K-Type Thermistor.
Are there then any issues with wrapping wire around the legs of a bead
thermistor, tying them to it with insulation tape, and connecting them
to a DMM with crocodile clips?


** Folks - we have ourselves a genuine " live one " here.

Could be a second cousin to Vicky Pollard as well.

Lotsa inbreeding involved - for sure.




...... Phil
 
I agree 100%.

Furthermore, there are many quite inexpensive DMMs with K-type inputs. A K-type
thermocouple is the simplest to use for the non-expert who doesn't want toget
involved in all the fuss with different themocouple materials.

One small point. K-type connectors used to be colour coded yellow. It seems to
have changed to green now for some daft reason. They are compatible though..

Graham-

Can you name some places selling them? I will check if any ship to
britain..

I will look into John Larkin's suggestion too, of cheap DVMs with K-
Type inputs.

According to this site
http://www.picotech.com/applications/thermocouple.html

K-Type refers to the metal the thermocouple (or perhaps, the
thermistor) , is made from. Not the plug.

Is there a chance that a K-Type Thermocouple from one place will not
plug into a Multimeter from another place?

I know for example that probes from one multimeter tend not to fit
into another one.
 
I would like to get a temperature probe like this, from an electronics
place.

How would it be described technically?  I know they have specific
names, for the form of the bit at the end.  K-Type e.t.c.

Here is a picture (it is measuring a HDD temp)http://www.overclockersclub.com/reviews/nzxt_sentry/images/12.htm

I am also interested in the same question, regarding this probe.
It is measuring CPU temphttp://www.overclockersclub.com/reviews/nzxt_sentry/images/9.htm

Note- I know there are other ways. Software, IR Temp sensor Gun, to
measure temp of components. But I am interested particularly, in these
temp probes like in the picture.  some wires and a thing on the end,
and you tape it to the component and read the temperature.

Thanks.

somebody somewhere, dunno if this thread..
mentioned a place called Omega. They have a uk branch..

I just spoke to their Tech.. REALLY GOOD

Just sharing the information here.. I am probably relaying him
wrongly.. But anyhow.. was very helpful.

I said I am just looking to measure temp off a hard drive.

(i.e. just putting / (taping actually) a probe on the bottom on the
back circle just off center (that is how they measure it in the
picture I linked to in my first post)

They said I can't just attach a thermocouple to a DMM, because I won't
get an accurate reading.. They won't have "Fault Junction
Compensation". He said Thermocouple (or K-Type?) sockets are more
common than Thermistor..

I guess maybe the ones with K-Type sockets -do- have that "fault
junction compensation". So give accurate readings.

They mentioned product HH11A £43.55 - so expensive. An LCD
displaying temperature, with a probe..
(this looks good, a bit like a product called compunurse that is hard
to find in the uk) For 10 quid more. A muiltimeter HHM15/HHM/16
with a temperature reading.

I asked about reading resistance and using a table.. He said nah,
because of the "Fault Junction Compensation" problem.. Don't go down
that route.
He said I would an RTD sensor for that. Not a thermocouple or
thermistor. And RTD sensors, he said are alot more expensive.
 
B

BobG

Jan 1, 1970
0
Well James, if you want to read temperature, and you have a computer,
then a MAX DS18B20 digital thermometer is just what you need. Its
digital. Wire length no prob. My second choice would be an LM35
temperature sensor... puts out analog 10mv/deg C... read it with an a/
d input.
 
E

Eeyore

Jan 1, 1970
0
Can you name some places selling them? I will check if any ship to
britain..

Farnell has them.
http://uk.farnell.com/jsp/search/br...&Ntk=gensearch_001&Ntt=thermocouple&Ntx=lists
some 100+

The simple bare junction type at the top of the list should do you find.

I will look into John Larkin's suggestion too, of cheap DVMs with K-
Type inputs.

They're all over the place. Funnily enough often on some of the cheaper Asian meters.
I've found these to be quite satisfactory.

According to this site
http://www.picotech.com/applications/thermocouple.html

K-Type refers to the metal the thermocouple (or perhaps, the
thermistor) ,

It does. The TWO metals in fact.

is made from. Not the plug.

The plug is colour coded to match the thermocouple, so as to avoid accidentally
mixing up incorrect thermocouples.
http://uk.farnell.com/jsp/search/br...h_001&Ntt=thermocouple&Ntx=&_requestid=349800

I see Farnell still stock the yellow type.

Is there a chance that a K-Type Thermocouple from one place will not
plug into a Multimeter from another place?

Not if it's the 'standard' plug.

I know for example that probes from one multimeter tend not to fit
into another one.

Not if they're 4mm types which all decent meters have.

Graham
 
E

Eeyore

Jan 1, 1970
0
They said I can't just attach a thermocouple to a DMM, because I won't
get an accurate reading.. They won't have "Fault Junction
Compensation". He said Thermocouple (or K-Type?) sockets are more
common than Thermistor..

He said 'cold junction' actually. I don't know how they get round that but trust me they do work.

However those cheap DMMs with K-type inputs actually perform very well. I 'calibrate' them with boiling water before
use and it's rare to see one even as bad as 2C out.

Forget thermistors totally.

Graham
 
R

Rich Grise

Jan 1, 1970
0
I see, K-Type refers to the power end, not the sensing end , which was
what I was wondering about.

I will get a DMM with a K-Type socket .. And a K-Type thermistor to
match.

Regarding material for the thermocouple.

That's what the "K" means.
http://www.rescal.com/Thermocouple alloys.htm

As to the mechanical aspects of the probe itself, you'd probably have
to work with your vendor on that, like look at their catalog pix, or
call them and ask.

Good Luck!
Rich
 
He said 'cold junction' actually. I don't know how they get round that buttrust me
they do work.

However those cheap DMMs with K-type inputs actually perform very well.
I 'calibrate' them with boiling water before
use and it's rare to see one even as bad as 2C out.

Forget thermistors totally.

I see.. and cold junction is only a thermocouple issue..

So I still use a table of resistance-temperature.. I don't need a
multimeter with temperature.

http://www.omega.com/manuals/index.html?s=h (they are a US and UK
company)
Though his DMM with K-Type input, was very expensive.. 60UKP/$120

He mentioned HH11A $65/30UKP. LED with probe, displays temp.
or as an alternative. the MM approach we are discussing.
HHM15/16. $120/60UKP. Multimeter with K-Type connector (happens to
display temperature)

It displayed temperature, so one didn't need a table.. I was willing
to get one that didn't display temperature, and thus I would use a
table. But I don't think he had any.

I now see - thanks to all the explanations!- that Thermistors have
nothing to do with K-Type and nothing to do with cold Junction
issue. Given that..

Should I still forget thermistors? Can't I get one with a standard
plug that fits a multimeter, too ? And if they can just be wired with
any wires, and don't need to be a special socket on the multimeter.
Isn't that ideal? Better than thermocouple? Or are they expensive?

He didn't mention any multimeter with K-Type connector, that did not
display temperature.
Are there any big places in the US that sell them? They might ship to
UK.

Going off the purpose a bit..Looking at why the tech on the phone said
what he said. I guess he just meant that a DMM(or DVM no doubt) with
K-Type input would have the circuitry to deal with the cold junction
issue. So He was prob saying that because of that, they would not be
inaccurate..I guess he was saying that I can't wire the thermocouple
to a multimeter without K-Type input, because of the cold junction
issue. Though as Peter Bennett said.. that won't work anyway because
the wires would have to be the correct metal. (So I would get the
correct metal wires, by getting a K-Type thermocouple with its own
wires and its own standard plug, which implies a DMM/DVM with that
socket!)

thanks!
 
Farnell has them.http://uk.farnell.com/jsp/search/browse.jsp?N=500005+1002025+106132&N...
some 100+

The simple bare junction type at the top of the list should do you find.


They're all over the place. Funnily enough often on some of the cheaper Asian meters.
I've found these to be quite satisfactory.



It does. The TWO metals in fact.


The plug is colour coded to match the thermocouple, so as to avoid accidentally
mixing up incorrect thermocouples.http://uk.farnell.com/jsp/search/browse.jsp;jsessionid=VK5NRESE3QUL4C...

I see Farnell still stock the yellow type.


Not if it's the 'standard' plug.


Not if they're 4mm types which all decent meters have.

Graham-

thanks for all the info.. I will contact CRC/Farnell tomorrow when
their lines are open.
 
P

Phil Allison

Jan 1, 1970
0
<[email protected]>

I see.. and cold junction is only a thermocouple issue..

So I still use a table of resistance-temperature.. I don't need a
multimeter with temperature.

http://www.omega.com/manuals/index.html?s=h (they are a US and UK
company)
Though his DMM with K-Type input, was very expensive.. 60UKP/$120

He mentioned HH11A $65/30UKP. LED with probe, displays temp.
or as an alternative. the MM approach we are discussing.
HHM15/16. $120/60UKP. Multimeter with K-Type connector (happens to
display temperature)

It displayed temperature, so one didn't need a table.. I was willing
to get one that didn't display temperature, and thus I would use a
table. But I don't think he had any.

I now see - thanks to all the explanations!- that Thermistors have
nothing to do with K-Type and nothing to do with cold Junction
issue. Given that..

Should I still forget thermistors? Can't I get one with a standard
plug that fits a multimeter, too ? And if they can just be wired with
any wires, and don't need to be a special socket on the multimeter.
Isn't that ideal? Better than thermocouple? Or are they expensive?

He didn't mention any multimeter with K-Type connector, that did not
display temperature.
Are there any big places in the US that sell them? They might ship to
UK.

Going off the purpose a bit..Looking at why the tech on the phone said
what he said. I guess he just meant that a DMM(or DVM no doubt) with
K-Type input would have the circuitry to deal with the cold junction
issue. So He was prob saying that because of that, they would not be
inaccurate..I guess he was saying that I can't wire the thermocouple
to a multimeter without K-Type input, because of the cold junction
issue. Though as Peter Bennett said.. that won't work anyway because
the wires would have to be the correct metal. (So I would get the
correct metal wires, by getting a K-Type thermocouple with its own
wires and its own standard plug, which implies a DMM/DVM with that
socket!)



** Folks - we have ourselves a genuine " live one " here.

Could be a cousin of Vicky Pollard as well.

Lotsa inbreeding involved - for sure.


...... Phil
 
Omega sells thermocouple probes and meters, and has a lot of notes and
tutorial stuff.

http://www.omega.com/

They have some nice, small, stick-on probes, sort of like tiny
band-aids. Lots of cheapish DVMs will read out type K thermocouples.

John-

omega is way too expensive, like $120 for a multimeter with temp
HHM15/16
and $60 for just an LCD with probe.


will contact CRC
 
The simplest for a one-off application such as this is an ordinary
diode junction whose forward "resistance" is measured with an ordinary
DMM on Ohms range.  The Ohms range drives a constant current through
the diode, and the diode's forward voltage drop falls with increasing
temperature.  This is *very* linear, better than almost anything else
you will find (vastly better than thermocouples or thermistors).  Not
to mention being dirt cheap, and available in fairly small packages.

The only drawback is that each unit must be calibrated individually,
which is why you don't see this used more often.  (It *is* commonly
used to sense CPU and other chip temperatures for fan activation,
where precise temperatures are not really needed.)

Calibration consists of inserting the diode into an ice bath,
then a boiling water bath, and noting the readings on the DMM.
Any intermediate temperature is found via simple interpolation.
You can also extrapolate outside this range.  The basic concept is
good from near absolute zero until the junction starts to melt.

Note that you may need to coat the diode leads with something to keep
the water from them during calibration.

Bob Masta


Many thanks to everybody for all their help..I am basically sorted
now, information-wise.. I know the terminology, and some options, and
places to look to buy.


infact - since you mention diodes, I see maplin have multimeters that
read temperature (a chip I guess, doing the conversion)
And their multimeters that do this - now at least - seem to use
diodes.
e.g.
item N73CG
http://www.maplin.co.uk/Search.aspx?criteria=N73CG&DOY=23m5
 
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