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I am making a custom hydraulic brake for my sim racing setup. The original brake uses a potentiometer which outputs 3.3V at no brake pressure and 0V at full brake pressure. My pressure transducer, when supplied with the same supply as the pot, outputs around 0.35V at no brake pressure and around 3V at full brake pressure. For reference, when supplied 5V, it outputs .5-4.5V.

I have setup this diff amp circuit and was able to reverse the output of the pedal.

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But I am now struggling to figure out how to shift it to hit 0V and start at 3.3V. How do I "exactly" calculate the resistors to achieve that function?

I have already considered an Arduino, but I would really like this to stay as simple as possible as far as hardware goes for resale considerations. An Arduino makes this much more difficult from that perspective.

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  • \$\begingroup\$ What is your pressure sensor? Datasheet? \$\endgroup\$ Jun 8 at 15:35
  • \$\begingroup\$ Please add a drawing of the original and what you have made so far. \$\endgroup\$
    – Aaron
    Jun 8 at 17:02
  • \$\begingroup\$ Can you calculate Vo as a function of the two inputs? \$\endgroup\$
    – Antonio51
    Jun 8 at 21:46
  • \$\begingroup\$ I don't find it easy to understand what you are trying to actually achieve. Are you trying to design a circuit which will give a certain output swing for a certain input swing. I think I understand that you are trying to achieve a 0V to +3.3V output swing for a +5V to 0V input swing, with 0V input giving +3.3V output and +5V input giving 0V output. Is this correct? What supply voltages do you have available? \$\endgroup\$
    – James
    Jun 8 at 22:23

1 Answer 1

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Here is a Maple sheet to calculate your components for that goal.

First, write equations.
Then, write your final conditions of working.
NB: one must use a rail to rail opamp.

enter image description here

enter image description here

NB line k:=1000; ..... should be deleted.

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