AMPLIFIER and superposition theorem

[tiwari.sachin]

Hello All

I have a few sensors whose outputs are +- 5V, +-10V and +-20V.

I need to have a circuit which will have these signals changed to 0-5V range so that it can be connected to the ADC.

for example: if i consider +-10V sensor, i should get output as follows.
+10 V --> 5V,
0V --> 2.5V
-10V --> 0V,


I got a circuit that should reasonably do the same but i am unable to understand how the final function has been derived.

I have attached the circuit and final formula. If anyone can help me understand how the final formula has been reached, it would be of great help. I understand that super position theorem has been used to reach upto the final point. I am somehow not able to get how it is done.

Regards
Sachin

 

[LvW]

There are three input voltages and each voltage causes a part of the output voltage (Vo1, Vo2, Vo3).
Using the classical formulas for inverting/non-inverting gain (-R2/R1 and (1+R2/R1), respectively) and the corresponding input voltage division ratios you get the mentioned three output signals which can be combined using superposition.

 

[franciscorc]

Hi all

Look, this is a very simple circuit . I place this just as a start point to your project.
It is likely you need much more precision.

Best Francisco

 

[engr.fawad]

Super Position Theorem Explained here

super position theorem