IC voltage mixing.

I have two voltages. 0 - 5 and 5 - 0 from op-amps.

I want to mix them together giving a unity gain ground (0 to 5) volts.

How do I it?

Thanks Ivan

Thanks Ivan

Here is what I am playing with.  I have a trimmer cap converted to voltage.  I have two op-amps reading signal from a charge pump like a cap checker.   One gives me 5 volts when the cap is fully meshed and the other gives me 5 volts when the cap is fully open.  I want to use these voltages to make it read 0 to 5 volts on one complete revolution.

That's an audio mixer and I am not sure that will do what I need.  That will give me 0 volts when ever the polarity reversed. Maybe it's not a mixer I am looking for.  I was thinking more like an instrument amp is what I want.  I want 0 out when the polarity is (+ to -)  and 5 volts out when the polarity is (- to +).

Thanks Harry and Ivan

I am using two op-amps one puts out (0 to 5) the other (5 to 0), in other words one is inverted.  The rail is 9 volts so I am ok there.  There are no minus voltages as it's a single supply.

Starting from the fully meshed point of the trimmer cap:

Comparing the two voltages, when the polarity reverses the trimmer will be only at the half way point. (fully meshed to fully open, 180 degrees) .  At this point the voltage needs to be 2.5 volts.  For the continuation of the rotation (180 to 360 degrees) I need to voltage to climb from 2.5 to  5 volts and drop to 0v when it completes one revolution. 

This circuit monitors a rotating mechanical metal plate and it not really a trimmer but works in exactly the same way.  It has 2 to 60 pf of capacitance.

I hope this clears up what I am trying to do.

Yes you are correct.  You chart is exactly what I am trying to come up with.

Here is what I am going to try next.   Let me know what you think.

First of all the op-amps are biased at about 1 volt because the capacitance doesn't drop all the way to 0 pf.  So the single power supply shouldn't be a problem with the 324 op-amp. 

Idea 1

My idea is this, using your chart I will use one op-amp in the 324 for a comparator looking at the output and set at 2.5 to switch in the output from the inverted op-amp that's biased  at 2.5. I am not sure how clean the switching will be this way but it might be alright with a good regulated supply.  

Idea 2

I can put an IR detector across the rotor of the capacitor to read it's position and let that control the switching. When the led is covered it would turn on the inverted amp.

This doesn't need to be a super accurate measurement.  Just close would be fine.

I guess I was just hoping to find a simple way to do this without the switches. LOL