Hrmm...  not sure I'm with you on that one.  With the wiper centered, your
input would still see 20K Ohms to either source.  Maybe I'm just slow or
theory-challenged, but I don't see how two resistors to two different
sources would qualify as "parallel".  I could be wrong though, here I am
posting from work again, which results in my being wrong about 3 out of 4
times it seems.

Dale
--
"Curiosity is the very basis of education and if you tell me that
curiosity killed the cat, I say only the cat died nobly."
          - Arnold Edinborough


On Tue, 11 Jun 2002, David Minkler wrote:

> Wrong.  40k max.  Assume the pot is wired from a pair of stiff sources
> (Vcc/Vdd and GND for example).  Worst case (highest impedance) will be
> with the wiper at mid-range.  Thats two 20k resistors in parallel for an
> equivalent wiper (input) impedance of 10k (as recommended in the data
> sheets).  Of course, I haven't seen a lot of 40k pots advertised lately
> (25k is a standard) so in that sense, maybe you are (approximately)
> right.

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads