Hi all, I've just joined the forum and am currently working on my final year project, a solar tracker - which by the looks of things isn't too uncommon on here!

I've been working with a window comparator (although without the outputs tied together) and a potential divider set up using CdS cells - the end goal being to take the two comparator outputs independently and feed them as logic supplies to an L293D motor driver (there's more to it but that's the basic idea).

I've had this setup working on breadboard with a variable voltage source standing in for the p.d. output and using a dual op-amp as my comparator (this may change later).

My question is - how do I reduce the sensitivity of the comparator? In my Lt Spice simulation and in practice, the comparator outputs change for the same of a few millivolts either side of the 6V reference.

I've based my design on there being a clear "no action" state when the p.d. voltage and ref are both at roughly 6V (i.e. half of my 12V supply). can anyone suggest a way to widen this state so that it takes 1V or more for the comparator to kick in?

Here is my schematic (ignore the diodes). This works correctly except for the sensitivity.

Any help would be much appreciated.

Cheers

 

Make the R1/R2 voltage divider three resistors so you can have a dead band of whatever you desire. See attached: