Homebrew PCBs

Regular price $40, I was just there and found it was down to
$26.99. A thermocouple is a tiny junction of two metals that makes
part of a highly accurate thermometer that can stand -very- high
temperatures.

This one goes up to 2000F or 1300C.

Harbor Freight Tools, Cen-Tech 92242. Reads in C, F, or K.

Since it is a contact thermometer, it does not matter what color
the surface is, unlike non-contact pyrometers where the surface
must either be a dark black/grey, or you have to stick a piece of
black high temp tape on it to test it.

It has some funky cheapo connections on the meter, I figure I can
replace those easily enough with something standard. Even a 1/8"
jack, as long as it's close enough to the cold junction
compensation.

Naturally I'll take it apart, I'll take a few pix of it.

FYI, they also have a 6" digital composite (ie, fibersomething
filled plastic) on sale for $8, inch or mm.

Steve Greenfield

On Sun, 27 Aug 2006 01:03:51 +0200, Steve Greenfield  
<alienrelics@...> wrote:

> Regular price $40, I was just there and found it was down to
> $26.99. A thermocouple is a tiny junction of two metals that makes
> part of a highly accurate thermometer that can stand -very- high
> temperatures.

You can also sometimes find type-k temperature ranges on multimeters. VERY  
useful, especially if it has PC link and/or min/max functions. You could  
use any meter sensitive enough, but it is nice to read degrees straight  
off the display. If the meter has cold junction compensation that's even  
better. One of mine doesn't and i found that out the hard way when it  
showed below freezing room temperature after i had just charged the  
battery and the meter was warm.

What probe does your meter use? I use an exposed junction most often, but  
plan to make one with a little contact plate since i now have the battery  
welder.

> It has some funky cheapo connections on the meter, I figure I can
> replace those easily enough with something standard. Even a 1/8"
> jack, as long as it's close enough to the cold junction
> compensation.

The plugs they usually use here are flimsy looking yellow things with flat  
contacts, those are the same material as the wires. But as you say near  
the cold junction it does not matter, i use standard 4mm plugs. (our old  
power plugs are 19mm prong distance and 4mm prongs so will fit most  
multimeters, i use those sometimes rather than two individual plugs)

Thermocouples are good things, i never felt the need to get an optical  
thermometer...

ST

>A thermocouple is a tiny junction of two metals that makes
>part of a highly accurate thermometer that can stand -very- high
>temperatures.

Commonly used in gas appliances like water heaters and furnaces in 
direct contact with the pilot flame. The voltage they output is used 
to control gas flow as long as there's a flame (sufficient heat). No 
flame...No gas...No danger. It's the second thing to check when these 
things stop working. Home Depot sells the type I'm referring to for 
less than $20.00 IIRC. I've replaced a few in my lifetime.

--- In Homebrew_PCBs@yahoogroups.com, Steve Greenfield 
<alienrelics@...> wrote:
>

Other Thermocouple Probes J, K, T types
[http://www.sciplus.com/singleItem.cfm?terms=5117&cartLogFrom=Search]