DS 3502 as Variable Resistor

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jim53
 
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Joined: Tue Sep 07, 2021 8:59 pm

DS 3502 as Variable Resistor

Post by jim53 »

Hello, I am trying to make an amplification circuit where I can vary the gain using a variable potentiometers. I am trying to create a differential op amp circuit that can amplify a range to 0-3.3 to try to get more precision out of a linear potentiometer.

The potentiometer converts position to voltage and has a max range of 10 inches. With a 12 bit ADC, the most precise measurement I can then get is .002 inches. Say I know the motion will stay within 2 inches, then we only have 819 steps instead of the full 4095. So the idea is to amplify the voltages in this 2 inch range to correspond to 0-3.3V, thus giving a full 4095 steps in the 2 inch range and increasing precision by a factor of 5.

So what I am doing is using a differential op-amp circuit where we subtract the lower value of the range, and then set the gain so that the upper limit is 3.3V while the lower limit remains at 0V. To achieve this, I was planning on using DS 3502 programmable potentiometers to set the two R1 values, while choosing R3 to have appropriate gains. I am not sure this will work though as I have been having issues with the DS 3502 and have found that RH seemingly needs to be connected to a power supply. Is my circuit feasible with the DS 3502, or will I need to find a different way to do this?
Screen Shot 2022-12-06 at 7.53.46 PM.png
Screen Shot 2022-12-06 at 7.53.46 PM.png (273.46 KiB) Viewed 33 times

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