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

Discussion in 'Electronic Basics' started by [email protected], May 22, 2008.

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  1. Guest

    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.
     
  2. BobG

    BobG Guest

    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.
     
  3. Guest

    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)
     
  4. Phil Allison

    Phil Allison Guest

    <

    ** 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
     
  5. Guest

    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.
     
  6. Eeyore

    Eeyore Guest

    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
     
  7. Guest

    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
     
  8. Phil Allison

    Phil Allison Guest

    <>

    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
     
  9. Phil Allison

    Phil Allison Guest

    "Blip" <>

    ** Blimp ????

    ** What part of "live one " is novel to you -

    you asinine fuckwit.



    ...... Phil
     
  10. Guest

    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.
     
  11. Guest

    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.
     
  12. BobG

    BobG Guest

    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.
     
  13. Eeyore

    Eeyore Guest

    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.

    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/br...h_001&Ntt=thermocouple&Ntx=&_requestid=349800

    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
     
  14. Eeyore

    Eeyore Guest

    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
     
  15. Rich Grise

    Rich Grise Guest

    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
     
  16. Guest

    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!
     
  17. Guest

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

    Phil Allison Guest

    <>

    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
     
  19. Guest

    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
     
  20. Guest


    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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