I am a beginner at circuit design, and I am having trouble using the Vout of differential amplifier as Vref of comparator. The other input of comparator is a potentiometer connected to Vcc and ground.
The problem I'm seeing is that, with a fixed voltage value of 2.32 V at the output of LTC1050, when I change the voltage output of the potentiometer, the output of LM358 also changes incrementally (not switching from 0 to Vcc based on which input voltage is larger, as expected of a comparator circuit).
The op-amp comparator (LM358) works as expected when I set Vref to be the voltage divider output of Vcc and ground. What is different about the Vout of differential amplifier? What should I do differently to make it work?
Any help would be greatly appreciated.
In case you want more info: I am trying to convert PWM to DC, amplify it with differential amplifier, and compare it to potentiometer value to drive an h-bridge. I am stuck at the part connecting the differential amplifier and comparator.
Per suggestion, here is a picture of my circuit. The only added part from the circuit diagram is 7.5V of power supply (2A max current) fed into 5V voltage regulator (L7805CV3) to produce 5V supply for all power lines.