AVR-Chat

On Mar 18, 2006, at 8:41 PM, Kathy Quinlan wrote:

> Hi all,
>
> Well I have to make 100 units (and pot them in Epoxy Resin) of an  
> octopus lure
> I designed for a proto run.
>
> I am now thinking SERIOUSLY about building my SMD oven (as it is  
> mainly SMD
> only 4 through hole solder connections and 2 through hole non solder
> connections (fishing line to hold the lure in the pot))
>
> I also have a lot of "other" projects including a run of 200 units  
> for my
> speed alarm unit for the Au Targa Rallys.
>
> So I need a circuit for Type K to AVR. I know there was a design  
> note in the
> Atmel applications Journal, unfortunately the WRONG schematic was  
> placed in
> there :(

SparkFun Electronics went through this process themselves, as did I.

I found that the toaster ovens were a bit slow, but if you doubled up  
the elements (i.e. buy 2 ovens, parallel elements) it helped.

You can use an AD595 thermocouple amplifier if you want.

Here's Sparkfun's schematic of their toaster oven controller:

http://www.sparkfun.com/datasheets/Tools/Reflow-Toaster-v2-Schematic.pdf

Sparkfun decided that an electric skillet was even better:
http://www.sparkfun.com/tutorial/ReflowToaster/reflow-hotplate.htm

You could do a simple bridge amplifier and do the cold-junction  
compensation yourself using a separate temperature sensor (for  
instance, you could use a Tiny45 which has an on-chip differential  
amplifier, and an on-chip temperature sensor).