[sdiy] really basic question .. tolerance

[diysynth]

Hi all, hi Tim,

> Rules... We don't need no stinkin' rules!
Oooh Yes we do....

100 KOhm with 1 %

to simplify, we have (with 1% tolerance) 99, 100 and 101 KOhm.
With 3 possibilities in a 2-combination :
9 Possible Combinations:

99 + 99 = 198  instead of 200 (i.e. 1% error)
99 + 100 = 199 (0,5%)
99 + 101 =200 (0%)
100 + 99 = 199 (0,5%)
100 + 100 = 200 (0%)
100 + 101 = 201 (0,5%)
101 + 99 = 200 (0%)
101 + 100 = 201 (0,5%)
101 + 101 = 202 (1%)

so, we have a arithmetic mean of tolerances of :
(1,0 + 0,5 + 0 + 0,5 + 0 +0,5 + 0 + 0,5 + 1) / 9 = 0,4444 %

That is, of course, better than 1%.
This estimation doesnt take into account, that 1% tolerance means, that
there is a gauss-distribution of the resistor values with a standard
deviation around 100 KOhm of  (less than) 1 KOhm or so. Tis would increase
this e-mail to some hundred lines.

Joerg









> clear now?
sorry, no.