Non-inverting op-amp question

[hazzer123]

I need to amplify a signal that varies around the range 2.4-2.6 volts, so that it outputs 0 - 5V.

I understand the basic circuit where the gain is 1+ (R2/R1), but i want an offset, where 2.4V into the V+ pin creates 0V on the output pin (and vice versa with 2.6V in = 5V out).

Any one have any ideas?

My op-amp has no balance pins.

[Soeren]

I need to amplify a signal that varies around the range 2.4-2.6 volts, so that it outputs 0 - 5V.

I understand the basic circuit where the gain is 1+ (R2/R1), but i want an offset, where 2.4V into the V+ pin creates 0V on the output pin (and vice versa with 2.6V in = 5V out).

So, you need a gain of ((5-0)/(2.6-2.4)) = 25, with an offset of -2.4V.

The offset will also see the amplication factor, so you need to add an offset of only -2.4/25 = -96 mV.

Since it's a negative numbe, easiest way is to lift your inverting input by 96 mV (since inverting a minus yeilds positive).

[Admin]

Another method Ive used is to have two seperate grounds.

Set the amplifier circuit ground to 0V, and set your microcontroller ground to 2.4V.

To do that, you would use a 2.4V regulator for microcontroller ground, and a 5V+2.4V regulator for the positive voltage of your microcontroller.

Then just design your amplifier gain to not go above the 5V+2.4V voltage.

Ok maybe not elegant, but it works really well!