In a message dated 98-02-24 12:16:14 EST, you write:

 <<
  > 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.
   >>

 Hello to everyone!
 Ive been in the hospital for a few weeks but I'm back now.

 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 is
sort of like setting out to write your own accounting software.  Check out
omega engineering.  they have simple setpoint controllers starting at about
$79.
 We use lots of them in our machines.  The ones we use are around $300 because
we control them via RS485.  Starting at about $500 you can get a decent
Ramp/Soak programable controller with 25 or so program steps. For this type of
controller we use the Watlow but there are many many others.  Most fit in a
1/4 or 1/8 DIN standard panel space.

 Just a thought

 Dave Duley

P.S. Sorry Lawrence for send this directly to you.  I forgot to check the TO
address.