This circuit will not do what you want. This circuit is a hysteretic comparator that will have two transition points. A HI->LO and a LO->HI. When the output of the comparator is LO, the voltage on the non-inverting input will be at the LO->HI transition threshold. Since it is an inverting comparator, all we know about the input voltage (the voltage at the invering input) is that it is somewhere higher than this voltage. Once the input voltage drops below this threshold, then the comparator changes state and goes HI and the voltage at the non-invering input changes to a higher threshold, which is the HI->LO threshold. So, to switch states again, the input voltage must rise not only above the threshold that caused the last switch, but a higher threshold. The same is true in reverse once it does cross that higher threshold -- the threshold changes back to the lower LO->HI threshold.Can anyone help with the operation of this circuit in the PDF file. RX and Ry are photocells. The main idea is that when RX and Ry see the same amount of light, the comparator should give a low signal.
But what's the point?I understand that to calculate these thresholds are also diffacult i beleive due to the change in inputs if i can be given a general set of equations that can be used to calculate the thresholds and input values it can also really help me.
Okay, this definitely helps and it is very, very different than what you stated in your original post:sensor A seeing less light the output is low.
if seeing the the same amount of light the ouput is low
sensor A seeing more light the output is high
That strongly implies that you want the comparator output to be low when they see the same amount of light and to be high otherwise, regardless of which one is seeing more light. This is further strengthened by the fact that you don't distinguish between Rx and Ry.The main idea is that when RX and Ry see the same amount of light, the comparator should give a low signal.