Fiz WROTE:A little more help here..
What the window comparator actually doing?
I'm quite slow here.
You can think of window comparator as an analog version of address decoder like 74138 or 74145. The 74138 will decode 3 bit binary data "000 to 111" to turn 1 out of 8 outputs low.
The window comparator here
http://ecelab.com/circuit-window-comp.htmwill produce a low output when the Vin is in between Vref (high) and Vref (Low)
In Page 7 of the datasheet of LM3914. You can see that LM3914 is a window comparator too.
http://www.energies.alba-annuaire.fr/data/lm/LM3914.pdfBy connecting 5V to RHI, the comparator will divide the V sigin by 10. Each increament of 0.5V will light up one LED linearly.
Allen