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I'd like to get the output on the right when applying the signal on the left to a signal conditioning circuit using op amps. enter image description here

I've got different slopes so I guess I need two amplifier circuits with different gains (16 and 24 plus a 2V offset). Even so how do I select one of the two? Using a third op amp used as a comparator? Is there a more obvious solution?

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  • \$\begingroup\$ Why not do the obvious and start with the signal on the right which is linear. Define tolerance errors for gain and offset \$\endgroup\$ May 17, 2020 at 23:10

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This does what you are asking with one dual op-amp. R1 and R3 give the gain of 16, and R2 increases the gain when the input voltage rises above 250mV. OA2 saturates to the positive supply for lower inputs. Since temperature is the variable, presumably speed is not of concern.

schematic

simulate this circuit – Schematic created using CircuitLab

enter image description here

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  • \$\begingroup\$ That's a clever solution. Thanks for helping! \$\endgroup\$
    – dodod
    Feb 22 at 17:40
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Since the gain must vary, and you have not defined any error band at the gain-switch point, you can use diodes in the opamp feedback path to change the gain as needed.

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