Amplify offset voltage

Question

I have a signal that varies between 3 volts and 4 volts. Now I want to amplify that 1 volt difference to a range from 0 volt to 5 volts.

I tried to find a solution with an opamp or a transistor, but hopeless. What can do the trick in place of the question mark?

schematic

^{simulate this circuit – Schematic created using CircuitLab}

And what you are doing is amplifying the signal after removing the offset, not amplifying the offset. — Ecnerwal, Dec 11 '13 at 21:10
Very similar to this: http://electronics.stackexchange.com/questions/30719/analog-voltage-level-conversion-level-shift — Andy aka, Dec 11 '13 at 21:10

score 2 · Answer 1 · edited Dec 11 '13 at 20:54

2

look into this amplifier, by putting 3v on one of the input pins you can filter that out, you have the option to invert the signal to (depends on which pin you place the 3V)

enter image description here

http://en.wikipedia.org/wiki/Differential_amplifier#Other_differential_amplifiers

edited Dec 11 '13 at 20:54

alexan_e

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answered Dec 11 '13 at 20:38

Robert Stevens

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score 0 · Answer 2 · answered Dec 12 '13 at 04:25

You need a circuit called a difference amplifier.

http://en.wikipedia.org/wiki/Operational_amplifier_applications#Differential_amplifier_.28difference_amplifier.29

Connect your input to the noninverting input of the difference amplifier. Connect the inverting input to the positive supply. Then calculate the inverting gain so that you get the offset you want, and then figure out what resistor values you need to get that gain. Then figure out what resistor values you need to get the correct gain for the noninverting input. The equation you need is listed right on the linked page.

Amplify offset voltage

2 Answers2