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Darrell,

I am expecting that the net effect would cancel itself out -- ie: to conn=
ect=20
metal A to metal B, if we conceptualize the soldered joint as a series of=
=20
smaller connections such that A joins to X, X to Y, Y to Z, then Z to A, =
then=20
the whole series would cancel itself out as long as all of the smaller jo=
ints=20
are at the same temp, and especially so if the joint is where the=20
cold-reference temp sensor is.

But I've had difficulties soldering the thermocouple wires to the board (=
tried=20
both stranded and solid wires, and tin/lead or silver solder).  Have not =
been=20
able to get any other acid solder, etc here.  So I've moved to plan B --=20
which is to crimp the ends to regular stranded copper wire, then solder t=
he=20
copper wires to the board.  The copper wires would be only about 1/4" to=20
1//2" inch long, and the crimped connection will be draped right over the=
=20
temp sesnor.

I was trying to see if I could fit a couple of those phoenix terminals (s=
crew=20
terminals) onto the board, but space is tight, especially since I've mana=
ged=20
to get the whole cold-ref control circuit (cold ref compensator / convert=
er /=20
amp & 20V boost regulator) into a 0.9" x 0.9" pcb.

Cheers,
-Neil.


On Monday 12 June 2006 12:18, Darrell Wyatt wrote:
> Neil,
>
> Don't know if you're aware of this, but the metals in the solder will a=
lter
> the signal when they come into contact with the thermocouple wires.  No=
t
> much help, I know, but I'd hate to see you put a
> lot of effort into something like this and have it fail to function as
> intended.
>
> D.
>
> >From: Picdude <picdude@narwani.net>
> >Reply-To: "Microcontroller discussion list - Public." <piclist@mit.edu=
>
> >To: piclist@mit.edu
> >Subject: [EE] Soldering thermocouple wire?
> >Date: Wed, 07 Jun 2006 22:25:42 -0700
> >
> >I tried to solder thermocouple wire to a PCB board, but the solder
> >(standard 63/37, rosin-cored tin/lead solder) would not adhere to it. =
 Is
> >there an easy way to solder this to a PC board?  I'd like to have the =
cold
> >junction right on the PC board, but space is really tight and I cannot=
 fit
> >a screw terminal in there easily to join the parts
> >
> >Any clues?  The thermocouple wire I have is solid, so not sure if that
> >makes a difference, but can't see why it should.  Or are there differe=
nt
> >types of k-type thermocouple wire such that one might be easily
> > solderable?
> >
> >Thanks,
> >-Neil.
> >
> >--
> >http://www.piclist.com PIC/SX FAQ & list archive
> >View/change your membership options at
> >http://mailman.mit.edu/mailman/listinfo/piclist
>
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