hi

I don't have any electronics background

I am looking for a multimeter with a K-Type plug socket,

And a Thermistor with wires going to a K-Type connector so it can plug
into it.

I will get a table of resistance to temperature, with the thermistor.

so I can measure the temperature of things.



I tried calling maplin technical(0906... thus expensive), but they
said they no longer sell K-Type multimeters. They prob know alot.

He said he thinks any multimeter with K-Type plug would support
thermistors and thermocouples.

He suggested I try RS components.

I tried RS components technical (0845..). She mentioned a multimeter.
It was extortionate - Fluke 179. £211, or £266 calibrated. The
calibrated one comes with bead type thermocouple. She said she
doesn't know if it supports thermistors too. The description only
mentioned thermocouple. I asked her - aren't they usually about £20.
She then mentioned another range that was £40, but I said forget it.


Does anybody know of a multimeter that does what I want?
Am I looking at the right price range? £20. Or should I be looking
at £40?
More than £40 is really too much.

There are cheap multimeters I have seen at maplin at one time, going
for 6 quid, just not with K-Type sockets.

thanks

wrote in message
...
hi

I don't have any electronics background

I am looking for a multimeter with a K-Type plug socket,

And a Thermistor with wires going to a K-Type connector so it can plug
into it.

I will get a table of resistance to temperature, with the thermistor.

so I can measure the temperature of things.



I tried calling maplin technical(0906... thus expensive), but they
said they no longer sell K-Type multimeters. They prob know alot.

He said he thinks any multimeter with K-Type plug would support
thermistors and thermocouples.

He suggested I try RS components.

I tried RS components technical (0845..). She mentioned a multimeter.
It was extortionate - Fluke 179. £211, or £266 calibrated. The
calibrated one comes with bead type thermocouple. She said she
doesn't know if it supports thermistors too. The description only
mentioned thermocouple. I asked her - aren't they usually about £20.
She then mentioned another range that was £40, but I said forget it.


Does anybody know of a multimeter that does what I want?
Am I looking at the right price range? £20. Or should I be looking
at £40?
More than £40 is really too much.

There are cheap multimeters I have seen at maplin at one time, going
for 6 quid, just not with K-Type sockets.

thanks



As far as I am aware , a type K refers to a thermocouple not a thermistor,
they are different in the way they measure temperature. A thermocouple
generates a voltage which changes with temperature. A thermistor does not
generate a voltage it exhibits a resistance which changes with temperature.

What is it you trying to measure the temperature of and how critical is the
size of the sensor.
If you were trying to measure the surface temperature of a small grass
leaf for example, you could not use a large sensor because it would
interfere with the actual temperature of the leaf. You also would have to
shield the sensor from external radiation (sunlight or a strong beam of
light)
So please tell us what you want to do with it.
Regards
Don

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "
saying something like:

Does anybody know of a multimeter that does what I want?
Am I looking at the right price range? £20. Or should I be looking
at £40?
More than £40 is really too much.

There are cheap multimeters I have seen at maplin at one time, going
for 6 quid, just not with K-Type sockets.

There are plenty of temp measuring DVMs around at twenty quid. I've got
a couple that use K - plugs, dead cheap and they are accurate enough for
my purposes.
Irrc, CPC supplied them a couple of years ago.
--
Dave
GS850x2 XS650 SE6a

"It's a moron working with power tools.
How much more suspenseful can you get?"
- House

On 22 May, 17:01, "Donwill" popple @diddle .dot wrote:
wrote in message

...
hi

I don't have any electronics background

I am looking for a multimeter with a K-Type plug socket,

And a Thermistor with wires going to a K-Type connector so it can plug
into it.

I will get a table of resistance to temperature, with the thermistor.

so I can measure the temperature of things.

I tried calling maplin technical(0906... thus expensive), but they
said they no longer sell K-Type multimeters. *They prob know alot.

He said he thinks any multimeter with K-Type plug would support
thermistors and thermocouples.

He suggested I try RS components.

I tried RS components technical (0845..). She mentioned a multimeter.
It was extortionate - Fluke 179. * £211, or £266 calibrated. * The
calibrated one comes with bead type thermocouple. *She said she
doesn't know if it supports thermistors too. The description only
mentioned thermocouple. *I asked her - aren't they usually about £20.
She then mentioned another range that was £40, but I said forget it.

Does anybody know of a multimeter that does what I want?
Am I looking at the right price range? £20. *Or should *I be looking
at £40?
More than £40 is really too much.

There are cheap multimeters I have seen at maplin at one time, going
for 6 quid, just not with K-Type sockets.

thanks

As far as I am aware , a type K refers to a thermocouple not a thermistor,

ok

that makes sense.. I heard it refers to type of metal.. and that
thermocouple has 2 different types of metal, to create a voltage
difference.

they are different in the way they measure temperature. A thermocouple
generates a voltage which changes with temperature. A thermistor does not
generate a voltage it exhibits a resistance which changes with temperature..


I know.. I don't mind measuring resistance and using a table.
or measuring voltage and using a table

or reading the temperature off an LCD display that displays
temperature.

What is it you trying to measure the temperature of and how critical is the
size of the sensor.snip

this one measuring a hard drive temperature
(so in that pic, the small sensor goes on the black circle at the
bottom of the hard drive. just off center. Quite a small sensor)
http://www.overclockersclub.com/revi.../images/12.htm

and maybe also this one measuring cpu temperature
http://www.overclockersclub.com/revi...y/images/9.htm
The [end of that] probe there looks long and tweezer like.

I wonder if there are names for the different ends.

wrote on 22/05/2008 :
hi

I don't have any electronics background

I am looking for a multimeter with a K-Type plug socket,

K-type is a thermocouple, K-type is the most common thermocouple and
the type most commonly used for multi-meters. One should cost you just
a couple of pounds or so, but you may need to source a suitable plug.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

On 22 May, 16:13, "
wrote:

I am looking for a multimeter with a K-Type plug socket,

Sounds expensive. Try RS or the on-line lab equipmented suppliers
instead and get a dedicated lab temperature meter that uses a K type
thermocouple. These are really pretty cheap these days.

Get some spare thermocouples too. Simple ones are cheap, bare wire
ones are easily broken. One of the easiest ways to break a
thermocouple is to try removing or installing it from equipment where
you'd have been a lot better off just buying and installing more of
them in the first place and leaving them alone once installed.

In message , Harry
Bloomfield writes
wrote on 22/05/2008 :
hi

I don't have any electronics background

I am looking for a multimeter with a K-Type plug socket,

K-type is a thermocouple, K-type is the most common thermocouple and
the type most commonly used for multi-meters. One should cost you just
a couple of pounds or so, but you may need to source a suitable plug.

Yeah but don't forget, the cable used to connect the thermocouple will
also affect the readings. The OP needs to specify the approximate
temperature range he expects to see (0-100c etc.) and then maybe we can
work out what he actually needs.
--
Clint Sharp

In message , Donwill
writes

wrote in message
...
hi

I don't have any electronics background

I am looking for a multimeter with a K-Type plug socket,

And a Thermistor with wires going to a K-Type connector so it can plug
into it.

I will get a table of resistance to temperature, with the thermistor.

so I can measure the temperature of things.

Does the OP want something like this ?

http://cpc.farnell.com/jsp/level5/mo...cpc/403321.xml


--
geoff

On Thu, 22 May 2008 18:15:19 +0100, Grimly Curmudgeon wrote:

Irrc, CPC supplied them a couple of years ago.

Toolstation do the Laser brand ones. Not very accurate though.

--
John Stumbles

I forgot to take my amnesia medecine again

On Thu, 22 May 2008 08:13:31 -0700 (PDT), "
wrote:


I will get a table of resistance to temperature, with the thermistor.

so I can measure the temperature of things.


Nooooooooooooooooooo !

Type K refers to a type of thermocouple, this is a device formed from
a junction of 2 dissimilar metals. It gives a voltage which varies
according to the difference in temp. over the whole circuit so you
need to know the ambient temp to start with.

However the multimeter typically does all that for you.


I tried calling maplin technical(0906... thus expensive), but they
said they no longer sell K-Type multimeters. They prob know alot.


Yes, about toy plastic helicopters and ghetto blasters ((

Take a look here :

http://www.maplin.co.uk/module.aspx?...48318&doy=22m5

£16.99

This has what they describe as a temperature test function. This might
do what you want.

He said he thinks any multimeter with K-Type plug would support
thermistors

Unlikely.

and thermocouples.

Type K only, there are others.

He suggested I try RS components.

I tried RS components technical (0845..). She mentioned a multimeter.
It was extortionate - Fluke 179. £211, or £266 calibrated. The
calibrated one comes with bead type thermocouple. She said she
doesn't know if it supports thermistors too. The description only
mentioned thermocouple. I asked her - aren't they usually about £20.
She then mentioned another range that was £40, but I said forget it.


Does anybody know of a multimeter that does what I want?
Am I looking at the right price range? £20. Or should I be looking
at £40?
More than £40 is really too much.

There are cheap multimeters I have seen at maplin at one time, going
for 6 quid,

2 for a fiver even.

just not with K-Type sockets.


There's more than just the socket involved.

DG

On Thu, 22 May 2008 22:51:30 +0100, Derek Geldard wrote:

On Thu, 22 May 2008 08:13:31 -0700 (PDT), "
wrote:


I will get a table of resistance to temperature, with the thermistor.

so I can measure the temperature of things.


Nooooooooooooooooooo !

snip



Agreed... Found one at Rapid!

http://www.rapidonline.com/Tools-Fas...quipment/Test-
Equipment/Multimeters/5-in-1-Digital-multimeter/79188

Seems to measure everything, but I don't know what accuracy is required.

--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info http://mixpix.batcave.net
Filtering everything posted from googlegroups to kill spam.

In article
,
wrote:
hi

I don't have any electronics background

I am looking for a multimeter with a K-Type plug socket,

And a Thermistor with wires going to a K-Type connector so it can plug
into it.

I will get a table of resistance to temperature, with the thermistor.

so I can measure the temperature of things.

Why a K-type connector? I have two multimeters that measure temperature -
a Maplin and a Fluke and they both use standard banana plugs for the probe
lead.


I tried calling maplin technical(0906... thus expensive), but they
said they no longer sell K-Type multimeters. They prob know alot.

He said he thinks any multimeter with K-Type plug would support
thermistors and thermocouples.

He suggested I try RS components.

I tried RS components technical (0845..). She mentioned a multimeter.
It was extortionate - Fluke 179. £211, or £266 calibrated. The
calibrated one comes with bead type thermocouple. She said she
doesn't know if it supports thermistors too. The description only
mentioned thermocouple. I asked her - aren't they usually about £20.
She then mentioned another range that was £40, but I said forget it.


Does anybody know of a multimeter that does what I want?
Am I looking at the right price range? £20. Or should I be looking
at £40?
More than £40 is really too much.

I'd check on Ebay. Loads of different multimeters on sale there and some
will do temperature. Not sure about the socket, though.

There are cheap multimeters I have seen at maplin at one time, going
for 6 quid, just not with K-Type sockets.

thanks

--
*When it rains, why don't sheep shrink? *

Dave Plowman London SW
To e-mail, change noise into sound.

On May 22, 8:29*pm, Clint Sharp wrote:
In message , Harry
Bloomfield wrote on 22/05/2008 :
hi

I don't have any electronics background

I am looking for a multimeter with a K-Type plug socket,

K-type is a thermocouple, K-type is the most common thermocouple and
the type most commonly used for multi-meters. One should cost you just
a couple of pounds or so, but you may need to source a suitable plug.

Yeah but don't forget, the cable used to connect the thermocouple will
also affect the readings. The OP needs to specify the approximate
temperature range he expects to see (0-100c etc.) and then maybe we can
work out what he actually needs.
--
Clint Sharp

0-100C

Not sure what wires to buy with the thermocouple..

I have heard that a thermocouple needs to be plugged into a special
socket for it.. e.g. K-Type thermocouple into a socket for K-Type
thermocouples.

So the multimeter geoff linked to wouldn't do it.. I didn't see that
socket on it.. though the picture was not big.

How about using a thermistor instead.. 'cos if that doesn't require
any special socket, wouldn't it be better?

I will call that company geoff and donwill and perhaps others too,
have mentioned. That CRC company. Their lines will be open tomorrow..

thanks

On May 22, 10:51*pm, Derek Geldard wrote:
On Thu, 22 May 2008 08:13:31 -0700 (PDT), "

wrote:
I will get a table of resistance to temperature, with the thermistor.

so I can measure the temperature of things.

Nooooooooooooooooooo !

Type K refers to a type of thermocouple, this is a device formed from
a junction of 2 dissimilar metals. It gives a voltage which varies
according to the difference in temp. over the whole circuit so you
need to know the ambient temp to start with.

However the multimeter typically does all that for you.



thanks.. I understand now.. about the Type-K(which I see only applies
as a type of thermocouple), and I see the difference between
thermistor and thermocouple.


But shouldn't I be able to use a thermistor with a multimeter?

With a table of resistance to temperature.




I tried calling maplin technical(0906... thus expensive), but they
said they no longer sell K-Type multimeters. *They prob know alot.

Yes, about toy plastic helicopters and ghetto blasters *((

Take a look here :

*http://www.maplin.co.uk/module.aspx?...48318&doy=22m5

£16.99


very interesting find, thanks
snip

On May 22, 11:25*pm, "Dave Plowman (News)"
wrote:
In article
,
* wrote:

hi
I don't have any electronics background
I am looking for a multimeter with a K-Type plug socket,
And a Thermistor with wires going to a K-Type connector so it can plug
into it.
I will get a table of resistance to temperature, with the thermistor.
so I can measure the temperature of things.

Why a K-type connector? I have two multimeters that measure temperature -
a Maplin and a Fluke and they both use standard banana plugs for the probe
lead.


my mistakes...
my understanading now is that
K-Type is a type of thermocouple. Multimeters need a special socket ,
the the female connector of it is i think some standard connector
thermocouples with leads use.
The socket's innards have to be for that specific type of thermocouple
being used e.g. Type-K.


Is it possible that your probe is a thermistor not a thermalcouple..
I am wondering if maybe thermocouples don't need a special plug.. or
even special wires.
So it may be easier with a thermistor.

So.. I would agree with your question really.. of why a K-Type
connector. Or rather, why a thermocouple - why not a thermistor?


snip
I'd check on Ebay. Loads of different multimeters on sale there and some
will do temperature. Not sure about the socket, though.

snip

good point.. though the advantage of these electronics places is they
have techical support telephone lines.

I'd check on Ebay. Loads of different multimeters on sale there and some
will do temperature. Not sure about the socket, though.

There are cheap multimeters I have seen at maplin at one time, going
for 6 quid, just not with K-Type sockets.

thanks


Agreed. EBay is your friend, here. A first search of "k-type" (a
Freudian slip of entering x-type initially provided very very different
results) shows on first page digital thermometers with 2 k-type
thermocouples thrown in for £21 (inclusive of P&P) from our friends in
China. Further down the pages plenty of spare thermocouples for around
£5 each inclusive of P&P.

If you can wait the couple of weeks for shipping then it's a simple
no-brainer rather than trying to deal with the high-street or CPC (maybe
they're good with tech support over the phone?, all I know is living
close by, I've stormed out from their trade counter after 50 minutes of
being given the wrong items)

On 23 May, 00:18, "
wrote:

Not sure what wires to buy with the thermocouple..

Thermocouple wires. Special magic ones, from the same shop as the
thermocouple.

I have heard that a thermocouple needs to be plugged into a special
socket for it.. e.g. K-Type thermocouple into a socket for K-Type
thermocouples.

Yes. Anything with a K type socket can reasonably be assumed to work
interchangeably with K type thermocouples, whether this is a
temeprature meter, a multimeter that also does temperature, a fridge,
oven, kiln or hamster-cosy.

Anything using banana plugs, jacks or phonos is most likely using
thermistors or semiconductor sensors, not thermocouples.

There are also two sorts of K type connector. Old ones were yellow,
new ones are green. They're not interchangeable, but you can convert
equipment by swapping the plugs and socket. Remember that polarity is
crucial!

You won't convert a standard meter (voltage or current) to read a
thermocouple without sufficint extra work to make it impractical, or
sufficient knowledge to appreciate why it's not a practical idea.

My K-type reader cost a tenner or so. They're really not expensive
these days.

wrote in message
...
hi

I don't have any electronics background

I am looking for a multimeter with a K-Type plug socket,



http://www.rapidonline.com/Tools-Fas...r/31051/kw/328

I have a couple of these in my electronics lab.

It does come with a probe, which plugs in to the small
rectangular green bit near the bottom right hand side of the meter.

On Thu, 22 May 2008 23:25:41 +0100, Dave Plowman (News) wrote:

snip

Why a K-type connector? I have two multimeters that measure temperature
- a Maplin and a Fluke and they both use standard banana plugs for the
probe lead.

snip

Because the output from the thermocouple is polarised it uses a special
polarised connector on installed systems. There are also standards for
the type (& colours!) of thermocouple connecting wire as this affects
accuracy of the reading. You need to use Type K wire with a type K
thermocouple for example. Using standard banana plugs may be acceptable
if your thermocouple is local to the instrument.

Ref:
http://www.picotech.com/applications/thermocouple.html

--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info http://mixpix.batcave.net
Filtering everything posted from googlegroups to kill spam.

submitted this idea :
0-100C

Not sure what wires to buy with the thermocouple..

I have heard that a thermocouple needs to be plugged into a special
socket for it.. e.g. K-Type thermocouple into a socket for K-Type
thermocouples.

So the multimeter geoff linked to wouldn't do it.. I didn't see that
socket on it.. though the picture was not big.

There is nothing special about the socket, other than the electronics
at the rear of the socket (the meter's electronics) are calibrated for
a K-type.

It does of course also need to be connected the correct way. The cable
also need needs to be the correct type for best accuracy, but those
probes designed for such use will already be fitted with a short lead
anyway.

If you use a thermistor ( can't see why you would want to), then your
meter will not provide a direct temperature reading - you will have
some maths to do to convert from the reading to a temperature.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

Andy Dingley explained on 23/05/2008 :
My K-type reader cost a tenner or so. They're really not expensive
these days.

As did mine from Mr Maplin and that included the K-type probe with
built in LCD display meter.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

In article ,
mick wrote:
Why a K-type connector? I have two multimeters that measure temperature
- a Maplin and a Fluke and they both use standard banana plugs for the
probe lead.

snip

Because the output from the thermocouple is polarised it uses a special
polarised connector on installed systems. There are also standards for
the type (& colours!) of thermocouple connecting wire as this affects
accuracy of the reading. You need to use Type K wire with a type K
thermocouple for example. Using standard banana plugs may be acceptable
if your thermocouple is local to the instrument.

Well, test leads on a multimeter are polarised too (by colour) for certain
operations but are interchangeable. I don't think you'll damage a K-type
sensor with reverse polarity.

--
*How do they get the deer to cross at that yellow road sign?

Dave Plowman London SW
To e-mail, change noise into sound.

On 23 May, 16:47, Harry Bloomfield
wrote:
submitted this idea :

0-100C

Not sure what wires to buy with the thermocouple..

I have heard that a thermocouple needs to be plugged into a special
socket for it.. e.g. K-Type thermocouple into a socket for K-Type
thermocouples.

So the multimeter geoff linked to wouldn't do it.. I didn't see that
socket on it.. though the picture was not big.

There is nothing special about the socket, other than the electronics
at the rear of the socket (the meter's electronics) are calibrated for
a K-type.

It does of course also need to be connected the correct way. The cable
also need needs to be the correct type for best accuracy, but those
probes designed for such use will already be fitted with a short lead
anyway.


I guess numbers on the LCD should indicate it in some obvious way.


Thanks... I am really sorted now, in terms of information. I know
what to look for. I know the terminology. I can see ones from maplin,
I can also try CRC and ebay.

I can get multimeters with temperature dispaying LCDs from maplin...
that use - I think - diodes (which seem similar to thermistors and
thermoprobes). And with ones that display temp, I don't need to do any
conversions.

I can look at CRC and ebay for multimeters or DVMs with K-Type
socket.. that just display voltage


You've all been extremely helpful.

many thanks


If you use a thermistor ( can't see why you would want to), then your
meter will not provide a direct temperature reading - you will have
some maths to do to convert from the reading to a temperature.

--

now-just out of curiousity..

similarly with a thermocouple surely.. Just your meter from maplin has
a temperature reading.. so I guess a chip in there converts voltage to
temperature. An equivalent meter with thermistor, would have a chip
that converts resistance to temperature.

so howcome all focus is in thermocouples? do the multimeters with
temperature readings not tend to use thermistors?


I don't see mention of K-Type Thermocouple for
N73CG , UT50C
They do mention Diode though.
so in defence of maplin tech. Maybe they really aren't selling
multimeters with K-Type thermocouples anymore.

formulated the question :
so howcome all focus is in thermocouples? do the multimeters with
temperature readings not tend to use thermistors?


I don't see mention of K-Type Thermocouple for
N73CG , UT50C
They do mention Diode though.
so in defence of maplin tech. Maybe they really aren't selling
multimeters with K-Type thermocouples anymore.

A thermistor is not suitable for the higher temperatures which would
cause it irreparable damage. A diode can be used to measure
temperature, but its again its junction could suffer permanent damage
above say 70 - 100 deg C.

K-types are good (from memory) to in excess of 700 to 1000 deg C.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

On Fri, 23 May 2008 17:00:59 +0100, Dave Plowman (News) wrote:

In article ,
mick wrote:
Why a K-type connector? I have two multimeters that measure
temperature - a Maplin and a Fluke and they both use standard banana
plugs for the probe lead.

snip

Because the output from the thermocouple is polarised it uses a special
polarised connector on installed systems. There are also standards for
the type (& colours!) of thermocouple connecting wire as this affects
accuracy of the reading. You need to use Type K wire with a type K
thermocouple for example. Using standard banana plugs may be acceptable
if your thermocouple is local to the instrument.

Well, test leads on a multimeter are polarised too (by colour) for
certain operations but are interchangeable. I don't think you'll damage
a K-type sensor with reverse polarity.

You won't damage it, but the temperature will read as a negative value!
Remember that a thermocouple is a voltage source. You are (basically)
using the meter as a voltmeter. A thermistor, on the other hand, isn't
polarity sensitive because it is simply a resistor whose value changes
with temperature. A thermocouple is far more difficult to read (linearly)
but handles a wider temperature range.

--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info http://mixpix.batcave.net
Filtering everything posted from googlegroups to kill spam.

On 23 May, 17:00, "Dave Plowman (News)" wrote:

I don't think you'll damage a K-type
sensor with reverse polarity.

The pins are different widths (and different metals). Physically
plugging it in backwards will break it (if you force it) and it
certainly won't work.

On 23 May, 16:47, Harry Bloomfield
wrote:

There is nothing special about the socket, other than the electronics
at the rear of the socket (the meter's electronics) are calibrated for
a K-type.

There's a lot special about that socket, mostly what the pins are made
of. Then it's unusual and polarized to stop you mis-plugging it with
anything else, or backwards.

In article
,
Andy Dingley wrote:
I don't think you'll damage a K-type
sensor with reverse polarity.

The pins are different widths (and different metals). Physically
plugging it in backwards will break it (if you force it) and it
certainly won't work.

Read the whole of the post you replied to.

--
*Before they invented drawing boards, what did they go back to?

Dave Plowman London SW
To e-mail, change noise into sound.

On 23 May, 17:33, "
wrote:

similarly with a thermocouple surely.. Just your meter from maplin has
a temperature reading.. so I guess a chip in there converts voltage to
temperature. An equivalent meter with thermistor, would have a chip
that converts resistance to temperature.

There's a more fundamental difference too. Thermocouples only measure
a temperature _difference_, thermistors measure an absolute
temperature. A thermocouple meter used to measure around "room
temperature" must also do something called "cold junction
compensation", where it applies a suitable offset to compensate for
the temperature that the meter end is at. This is tricky to do well.
One way is to _know_ the cold junction temperature, by sticking it
into melting ice or some fairly standard temperature. Another
electronic way is to buy a chipset from Burr-Brown or similar that
does the hard work for you.

Of course if the thermocouple is measuring a high temperature such as
a kiln, then the few degrees either way for the room temperature end
is neither here nor there. Room temperature is usually constant within
a few tens of degrees, or else the wetware complains. This is one
reason why thermocouples are still popular for high temperature work,
but the low temperature stuff was largely taken over by thermistors
(from 20 years ago), and these days by semiconductor sensors (less
sensitive to connection-induced errors).

On 23 May, 23:49, "Dave Plowman (News)" wrote:

I don't think you'll damage a K-type
sensor with reverse polarity.
The pins are different widths (and different metals). Physically
plugging it in backwards will break it (if you force it) and it
certainly won't work.

Read the whole of the post you replied to.

If you physically plug a K type in backwards, you'll snap something.
This might not be "reverse polarity" causing the damage, but you've
buggered it up all the same.

In article
,
Andy Dingley wrote:
I don't think you'll damage a K-type
sensor with reverse polarity.
The pins are different widths (and different metals). Physically
plugging it in backwards will break it (if you force it) and it
certainly won't work.

Read the whole of the post you replied to.

If you physically plug a K type in backwards, you'll snap something.
This might not be "reverse polarity" causing the damage, but you've
buggered it up all the same.

If you read my post you'd see I was referring to my two meters which use K
type sensors which plug into the normal banana plug sockets. Like every
other DVM I've seen which does temperature measurement. There's simply no
reason to provide a special socket for the temperature function on these
since the sensor can't be damaged by wrong connection. Of course it won't
work properly - but the plugs on the sensor are colour coded so that's
hardly a problem.

--
*Why is the third hand on the watch called a second hand?

Dave Plowman London SW
To e-mail, change noise into sound.

On 27 May, 12:04, "Dave Plowman (News)" wrote:

If you read my post you'd see I was referring to my two meters which use K
type sensors which plug into the normal banana plug sockets.

You wrote "standard banana plugs for the probe lead.", not "piece of
inaccurate crap that's so badly designed as to run thermocouple
signals through banana plugs". I didn't realise you even meant
thermocouples here - there are plenty of packaged thermometer probes
around that will give a nice simple voltage output so they work with
any meter (or measure rpm, or windspeed, or pH etc.). These quite
rightly use bananas.

Fluke do (or did anyway) make an adapter for fitting K types to
bananas, but it's a bad idea. It's a particularly bad idea for low
temperatures not much different from the temperature of the meter
housing. The problem that it isn't a thermocouple any more, it's a
daisy chain of several thermocouples. You're as likely to be measuring
temperature differences from how warm the meter is, rather than the
junction you want. If Fluke build a decent thermocouple cold junction
front end and package it into a meter behind standard jacks (Why? K
sockets aren't expensive) then it probably works OK for a kiln, but I
wouldn't trust it below boiling water temperatures.

Assuming that such an adapter plugged into a simple voltmeter would be
any more than a random number generator would certainly be a mistake.
If the contact resistance goes high and the meter impedance is that of
a DVM front end, you'll just be measuring contact noise, not the
couple's output at all.

In article
,
Andy Dingley wrote:
If you read my post you'd see I was referring to my two meters which
use K type sensors which plug into the normal banana plug sockets.

You wrote "standard banana plugs for the probe lead.", not "piece of
inaccurate crap that's so badly designed as to run thermocouple
signals through banana plugs"

One of them is a Fluke. And it certainly isn't 'inaccurate crap'
A DVM with a temperature measuring function wouldn't necessarily be of the
same design as a device meant solely for that purpose. Otherwise it would
have sockets scattered all over the place.

BTW - what's so special about a K type plug - apart from being polarised?

I've seen expensive temperature measuring devices designed for building
into machinery where the connections to the probe are simply screw
terminals...

--
*Hard work has a future payoff. Laziness pays off NOW.

Dave Plowman London SW
To e-mail, change noise into sound.

On 27 May, 13:46, "Dave Plowman (News)" wrote:

One of them is a Fluke. And it certainly isn't 'inaccurate crap'

Measuring temperatures comparable to the meter housing, it will be. It
might not be inaccurate in use, but only because the valid range of
use is limited to only measuring much higher temperatures. Like I
said, I wouldn't trust this below boiling water.

To be honest, this is the bane of thermocouples anyway. The single
most useful lesson I learned from a whole degree in applied physics is
that you don't trust any measurement based on comparing the
differences between two very similar direct measurements. Your
inaccuracies become proportionately far more important, relative to
the measurement value you're after. This is why cold-junction
compensation is so important and hard to design with competently, and
why so many thermocouple-based measurements of lower temperatures are
woefully inaccurate.

I've worked on one site where switching a $50 input board for a $10
input board (flakey cold junction design) and a "saving" was then
costing about $50k over a year in wasted energy - just from bad
measurements off a thermocouple. They even had spreadsheets (based off
that same thermocouple) to show how much they were now "saving" in
energy. Funny thing is the fuel bills didn't reflect this.

BTW - what's so special about a K type plug - apart from being polarised?

Pins are made of matching metals to the wires. This avoids creating
extra Seebeck junctions other than where you're measuring, and the
single cold junction you're keeping a careful eye on.

I've seen expensive temperature measuring devices designed for building
into machinery where the connections to the probe are simply screw
terminals...

Yes, provided that the screws and receptacles are made of the right
alloys (or at least plated with them). One of the attractions of a K
type is that the metals used are affordable and mechanically suitable
for doing this with.

In article
,
Andy Dingley wrote:
One of them is a Fluke. And it certainly isn't 'inaccurate crap'

Measuring temperatures comparable to the meter housing, it will be. It
might not be inaccurate in use, but only because the valid range of
use is limited to only measuring much higher temperatures. Like I
said, I wouldn't trust this below boiling water.

It's as accurate as needed at room temperature - measured against a
mercury thermometer. I wouldn't expect it to be accurate to within a few
decimal places though.

I'd suggest you try one before spouting off. ;-)

--
*I'm pretty sure that sex is better than logic, but I can't prove it.

Dave Plowman London SW
To e-mail, change noise into sound.

On 27 May, 16:46, "Dave Plowman (News)" wrote:

I'd suggest you try one before spouting off. ;-)

I suggest you learn how a thermocouple works before believing that a
brandname badge on the front will make physics work differently for
that maker's products.

In article
,
Andy Dingley wrote:
I'd suggest you try one before spouting off. ;-)

I suggest you learn how a thermocouple works before believing that a
brandname badge on the front will make physics work differently for
that maker's products.

You suggested that my Fluke is useless at anything less than about 100C.

You're wrong. Just live with it.

--
*Vegetarians taste great*

Dave Plowman London SW
To e-mail, change noise into sound.

wrote in message
...
On May 22, 8:29 pm, Clint Sharp wrote:
In message , Harry
Bloomfield
wrote on 22/05/2008 :
hi

I don't have any electronics background

I am looking for a multimeter with a K-Type plug socket,

K-type is a thermocouple, K-type is the most common thermocouple and
the type most commonly used for multi-meters. One should cost you just
a couple of pounds or so, but you may need to source a suitable plug.

Yeah but don't forget, the cable used to connect the thermocouple will
also affect the readings. The OP needs to specify the approximate
temperature range he expects to see (0-100c etc.) and then maybe we can
work out what he actually needs.
--
Clint Sharp

0-100C

What accuracy and/or precision

http://en.wikipedia.org/wiki/Thermocouple

in their picture they have the same meter I have by the looks of it.
http://www.rapidonline.com/Tools-Fas...D%20multimeter

at under £20 including the probe, but don't expect accuracy of 0.01C
trust it to be within a a couple of Cs.
I've tried the two I have here swapping the thermocouples around gives
a range of readouts between 18C & 21C. The meters themselves seem
to be about 1-2C difference with no probe connected.

What are yougoing to use it for, my use was to test the temerature
of an electric cookers oven as teh numbers on teh dial had all
been wiped away. I checked it with another oven and setting the oven temp
to 200C got meter results between 196C and 203C or there abouts which
I thought was accurate enough for my use.


Not sure what wires to buy with the thermocouple..

I have heard that a thermocouple needs to be plugged into a special
socket for it.. e.g. K-Type thermocouple into a socket for K-Type
thermocouples.

The rapid meter 328 comes with the theremocouple no lead(s)
required. (includes socket too)



How about using a thermistor instead.. 'cos if that doesn't require
any special socket, wouldn't it be better?

Not really, as you'd have to construct a circuit for it.
The meter has a switch position 'calibrated' for the thermocouple
so just read the Cs of the scale direct.

On May 28, 5:09*pm, "whisky-dave" wrote:
wrote in message

...
On May 22, 8:29 pm, Clint Sharp wrote:





In message , Harry
Bloomfield
wrote on 22/05/2008 :
hi

I don't have any electronics background

I am looking for a multimeter with a K-Type plug socket,

K-type is a thermocouple, K-type is the most common thermocouple and
the type most commonly used for multi-meters. One should cost you just
a couple of pounds or so, but you may need to source a suitable plug.

Yeah but don't forget, the cable used to connect the thermocouple will
also affect the readings. The OP needs to specify the approximate
temperature range he expects to see (0-100c etc.) and then maybe we can
work out what he actually needs.
--
Clint Sharp
0-100C

What accuracy and/or precision

http://en.wikipedia.org/wiki/Thermocouple

in their picture they have the same meter I have by the looks of it.http://www.rapidonline.com/Tools-Fas...quipment/Test-...

at under £20 including the probe, but don't expect accuracy of 0.01C
trust it to be within a a couple of Cs.
I've tried the two I have here swapping the thermocouples around gives
a range of *readouts between 18C & 21C. The meters themselves seem
to be about 1-2C *difference with no probe connected.

What are yougoing to use it for, my use was to test the temerature
of an electric cookers oven as teh numbers on teh dial had all
been wiped away. *I checked it with another oven and setting the oven temp
to 200C got meter results between 196C and 203C or there abouts which
*I thought was accurate enough for my use.

hard drive temp..
ideally would want a flat shaped piece of metal that I can tape to the
hard drive.

The place to measure, apparently is on the bottom, there is this black
circular area. A small bit of flat metal will do. Like this

http://www.overclockersclub.com/revi.../images/12.htm


Not sure what wires to buy with the thermocouple..
I have heard that a thermocouple needs to be plugged into a special
socket for it.. e.g. K-Type thermocouple into a socket for K-Type
thermocouples.

The rapid meter 328 comes with the theremocouple no lead(s)
required. (includes socket too)


I see, from
rapidonline.com
http://www.rapidonline.com/Tools-Fas...eter/31051/kw/

I am glad I am getting more options...

They all seem to involve the multimeter with the LCD screen, looks
like the way things are done..

I don't see many options in types of probe though..
Fair enough, K-Type thermocouple probe

But the contact at the end..

Ideally, I would like it to be like in that picture.

BTW, how did you measure in the oven, did you stick the probe to the
outside?

How did you not burn the jacket of the wire?

How about using a thermistor instead.. * 'cos if that doesn't require
any special socket, *wouldn't it be better?

Not really, as you'd have to construct a circuit for it.
The meter has a switch position 'calibrated' for the thermocouple
so just read the Cs of the scale direct.-

with a table with C and resistance, it should be fine though, right?
no need for a circui/chip to do the conversion. I assume this is the
circuit you refer to.

On 28 May, 22:12, "
wrote:

BTW, how did you measure in the oven, did you stick the probe to the
outside?

How did you not burn the jacket of the wire?

Either bare wires, well separated, or else you use a rigid metal tube
probe, packed full with mineral (electrical) insulation and the wires
separated inside.

If you make your own rigid probes, the trick is to first glue the
wires into a "stick" of wire + filler + wire on a piece of thin
paper, all held together with waterglass. Once dry, burn the paper off
with a small blowtorch. You can pack this rigid but fragile gluestick
(carefully) into the tube without shorting anything out, then pack
more filler round it.

Don't place a thermocouple near an induction-heated crucible, or bad
stuff happens...