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Okay so I am working with an Arduino Uno and the uno only outputs from 0-5 volts. I am using a breadboard and I built the circuit below using a LM471 Op-Amp and I am trying to boost the voltage from 0-10 volts doing simulations it works just fine and when I input 5 volts it does 10 volts outputs and when I do 4 volts it outputs 8 volts and so on. I built the circuit but when I check the voltage it only outputs 5 volts.

My quesiton... is there something I can do see what I am doing wrong? why am I getting only 5 volts for output when I should be getting 10 volts. Any type of help would be great. Thank you.

schematic

simulate this circuit – Schematic created using CircuitLab

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  • \$\begingroup\$ Is the midpoint of that 22V supply connected to GND (0V)? Making +/-11V. It should be... \$\endgroup\$ Jul 6 '15 at 21:13
  • \$\begingroup\$ Make sure the two grounds are connected (the Arduino ground MUST go to the midpoint of the op-amp supply as Brian suggests). Then measure the voltages on pins 2 and 3 of the 741. They should be equal and vary with the PWM. Your resistors are a bit low and will adversely affect the linearity and range (10V may not be achievable in any case). Try 20K for all (and you can reduce C1). In your case (2K load on the op-amp output) the op-amp requires a supply of +15 to be guaranteed to get to +10V on the output. The minus supply could be -5 or -7V. \$\endgroup\$ Jul 6 '15 at 22:17
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I agree with Kevin. Make sure your supply is beyond that of your output signal. So -Vcc=-5V and +Vcc=15V should work nicely for a 0-10V output. Also keep in mind that an RC circuit has filtering effects. In your case it acts as a low pass filter, so for high frequencies you might see a large magnitude decrease. I know people say it a lot, but it is also important to remember that real world problems don't always behave like simulations. Tolerances can effect precision. Good luck! Josh

Edit: I did a quick calculation and found that your cut off frequency is ~0.5Hz. If you are only dealing with DC, it shouldn't be an issue. But just in case.

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You don't show the ground of the 22V power supply connected to the Arduino ground - is it? It will not work correctly without that. What you actually need is a positive supply of 13-15V and a negative supply of -5 to -15V.

The 741 is a very old amplifier and needs the power supply to be at least 3V beyond the required output voltage. A more modern (although still very old) amplifier such as LM324 would not need a negative supply.

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