Resistor values for a non-inverting op-amp with gain of 2

Question

I'm trying to build a circuit that uses a non-inverting op-amp to double the voltage in the circuit. The op amp I'm planning on using is: http://www.farnell.com/datasheets/2258629.pdf , and I think it needs to be set up in this configuration: https://upload.wikimedia.org/wikipedia/commons/4/44/Op-Amp_Non-Inverting_Amplifier.svg. My question is what should the value of resistance of these resistors be? I know they have to be equal in value but am unsure about the absolute size of the resistance.

For reference the voltage going into the op-amp will be between 0-5V coming from an Arduino Uno power rail and varied through a potentiometer.

Thanks

Edit: The current circuit is as below, my thinking in response to the points raised about the voltage across the op-amp, is to put it in parallel to the proportional servo valve, hence running it off the 24V supply. My concern is that the current in that is 0.5A, which I understand wont all go into the op-amp, but the data sheet says the op-amp has a 2mA max limit. Does it have a feature built in that stops it accepting more than this, or will it try to accept more than this if given the opportunity and I'll end up breaking it?

Answer 1

^{simulate this circuit – Schematic created using CircuitLab}

Figure 1. Circuit modified after comments.

• The device has a 0 - 10 V option.
• You have a 24 V supply.
• Adding R2 on the supply to R1 forms a potential divider. The maximum voltage out of R1 will be \$ \frac 1 {1 + 1.4} \times 24 = 10 \ \text V \$.
• The pot can be adjusted from 0 to 10 V.
• The R3-R4 potential divider gives 0 to 5 V feedback to the microcontroller.

That's it!

Answer 2

A good start for approximate range of resistor values in low-frequency op-amp circuits is 10K. That's because bias currents and leakage have little effect and they don't draw too much current from the op-amp output or from the inputs (where relevant, which isn't here).

You might go up by 10:1 or more if the circuit has to be very low power, you might go down by 10:1 or more if the circuit needs to be very low noise or high frequency.

That's just a rough rule of thumb. The details depend on the exact requirements, but often there's a fairly wide range of possible values.

Of course, as Transistor mentions, to get 10V out you'll need a power supply of more than 10V, something like 12V is often enough. If you don't have a 12V supply, it can be created with a DC-DC boost converter.