> In a message dated 98-02-24 12:16:14 EST, DREITEK writes:
>
> <<
>  > I am planning to build a controller for a ceramic kiln.
>  > I try to convert thermocouple mV with a TL501 dual slope
>  converter > that has an accuracy of 0,05% FS.
>   >>
>

> I don't want to kill your fun but I specialize in Kiln control of
> industrial ceramic kilns.  I highly recomend that you don't
> re-invent the wheel.  It is rarely cost effective to build your own
> kiln controller these days.

It's also not cost effective to have eighth graders work Algebra
problems - they've all been done before too.

Most of us PICsters had to walk before we flew.  Going thrrough the
exercise of making a temperature controller, controlling a seven
segment display driving scheme, or some other task that was first
done half a generation ago is necessary for anyone who wants to get
good at this.

I just finished an cooking oven controller that used a thermistor
(Which was probably first done by Edison's assistant) and learned a
lot about oven performance.  I started out with a simple enough
control scheme - a sort of  on-off thermostatic control, that
resulted in broiling the tops of all the pies and muffins.  Back to
the Keyboard!  I ended up using a proportional control scheme that
kept the duty cycle on the heating elements low enough to prevent
them from getting cherry red.  This prevents burning the top of the
food, and also resulted in an extremely smooth temperature profile.

I'm sure I reinvented the wheel many times.  But I got paid for it!

Best Regards,

Lawrence Lile