On Mon, 8 Sep 1997, Lawrence Lile wrote:

> Famous Quotations from Patz R.  :
>
> > I am currently designing a temperature sensor using a 16C54 and the
> > AN512. This involves charging a capacitor via two resistors

 <snip>

> I've used it on several projects.  I had a lot of problems with drift
> and noise.  I had one project that wouild hold a temperature setpoint
> then slowly drift off by 25 C per hour.   One project ended up
> hinging on a good enough averaging and noise immunity algorithm - any
> ONE measurement was completely unreliable.

I'm also trying to use this method on a project and am having the
same types of problems.  Lots of drift, and maybe some noise. Not
sure what's causing it or how to cancel it's effect.   The
thought crossed my mind to take like, 10 measurements for every
display update, and average them out.  Haven't gotten around to
doing this yet though, because I don't think it will help the
drift problem. Only the noise. If anyone has an algorithim that's
already working I'd love to see it :)

I'm also investigating the posibility of using a PIC with an a/d
on it and doing it that way. I wonder if the a/d will have the
same problems though?

-Shane.