Homebrew PCBs

<http://www.nhsouth.com/crafts/workbench/thermocpl.htm>

If you need an output referenced to zero this would be a better circuit:
<http://circuits.linear.com/images/60789_TA01a.JPG>

You can leave out the LT1025 if you don't need cold junction
compensation and connect to ground instead.

There's a soldering iron temp control circuit on the E_101 list, works
just fine for a laminator:
<http://f1.grp.yahoofs.com/v1/gAg7S0za6gl3TT5Ydgb_GpwD3zXiCQbn_JBa5sm7Ttd6Yau1fx5nvLt6I8Wxcw5TBnPZF0P4miAvCkPh1EJPAVMu67omGp37ZhPsRA/Adrian%27s%20stuff/DIY%20Soldering%20Station/Termostat%20Schematic.pdf>

<http://groups.yahoo.com/group/Electronics_101/files/Adrian%27s%20stuff/DIY%20Soldering%20Station/>

But the thermistor will work too, you could probably connect a voltage
divide made of it directly to an ADC.

If you have the opamps and soldering iron out anyway, why not make an
analog controller? You are 90% done already.

ST

On Wed, Dec 30, 2009 at 3:06 AM, sailingto <sailingtoo@...> wrote:
> Thanks for the info - since I'm not sure about how to build an Opamp circuit, I found some thermosistors on digikey I think I can use.  They are 1,000 ohms at 25C and 2300 ohm range at 175C.  I think I can get decent control....  maybe I should say "sufficient" control?
>
> I should be able to show temperature on a LCD display and control a relay both with that for a temperature controller.  I'll work on that.
>
> "IF" I knew which AVR chip had a 200x internal amplifier I "think" I could make a type J thermocouple work with that.  I've got a couple feet (or 3ft?) of type J lying around.
>
> Ken H>
>