# Can I use a simple voltage divider with an instrumentation amplifier to measure from 0 to 10V?

There is a design of a circuit proposed in the following way: simulate this circuit – Schematic created using CircuitLab

The amplifier has a gain of 80, on R1 when the input voltage is equal to 10 V, it will be approximately 41 mV and when amplified by the OP would have 3.3V, which is the maximum volatje of the ADC of an MCU.

Could there be some kind of problem with this design?

The idea of using the voltage divider is to prevent the negative terminal of the voltage source (0 to 10V) from being connected to the ground of the main circuit, ie to isolate it in a certain way.

• whether that will be sufficient depends on the rails that OA1 uses, what its input common mode voltage range is, what the potential between the grounds is, and whether it has a low enough common mode input impedance. Unless all those are valid together, you may well be outside its common mode input voltage range, which is not going to work. You either need to define the voltage difference between the two circuits by some suitable connection, or use a different topology for OA1. – Neil_UK Jun 14 '19 at 16:22
• can you elaborate on what is your voltage source? – vangelo Jun 14 '19 at 16:24
• Thanks for writting. The input source is undefined, it can be a temperature or pressure sensor, anything that a user can connect and its voltage is variable between 0 to 10V. Is there a circuit or design that is better to measure this voltage? – user3249244 Jun 14 '19 at 16:28
• What's the goal? Dividing by 250 and then mutiplying by 80 is going to introduce noise to the signal. What are you trying to get in return? – The Photon Jun 14 '19 at 16:31
• Please let us know if what Neil_UK commented is not clear for you. Common mode voltage is very important. "Undefined" voltage sources may (or may not) work on simulations with ideal components but real circuits have many important issues you should be concerned about. – vangelo Jun 14 '19 at 16:33 