It would have been easier if you had a sensor that went the other way 30 (empty) to 240 full.
I hope someone comes along and helps because I'm extremely swamped with real work. I hang around here to relax, bedtime or whatever. I should be sleeping right now.
I.m not too familiar with the bar graph display, but a constant current source, say 10 mA across 240 ohms would be 2.4 V. A part such as this (AD8226)
https://www.analog.com/en/specialty...ation-amplifiers/ad8226/products/product.html can invert by switching the input leads. By applying a reference of 2.4V, the output would be zero. (assuming a gain of 1). But, the offset needs to be a little lower than that. 0.01*20 or 0.2 V lower.
So, now you have a signal that's 0 to 2.2 V. (which isn't likely the right number)
This is just an example and not design equations, but it uses simple numbers to get the point across. Many IA's (Instumentation amps) nned to be driver with a low impeadance source (not sure about this amp). 2.5 is a standard reference voltage, otherwise that may have to be variable and buffered. The LM431 might be a good choice here:
https://www.google.com/url?sa=t&rct...Nb3WsPEx8KXVyz9vZ0GYexQ&bvm=bv.77161500,d.b2U
You may need an OP amp to buffer the reference.
The LT3086
https://www.google.com/url?sa=t&rct...RVGD3t77CWkkcWsXl-jZtNQ&bvm=bv.77161500,d.b2U might not be a bad choice for a current regulator.
So, tweaking the current source adds gain. I didn't take into account lots of things. I didn;t look at the LM3815, for instance. I just assumed 0-2.2 V.
The "other" components aren't covered for power supply protection and/or regulation or the possible selection of a buffer amplifier.
You can get
www.proto-advantage.com to mount a surface mount package to a DIP header that they make.
So, a lot more work.