Welcome to Amateur Hour. Currently trying to convert a 3.3v signal from my Axoloti into 5v signal for CV. The 5v is arbitrary and I plan to change it once I know what I’m doing here.
This is my first venture into doing a circuit by myself and I figured that the non-inverting amplifier would do the trick.
For R1 I’m using a 1k resistor, and for R2 it’s a 620 ohm. The op amp is connected to my ±12v power supply.
For context for the next images, Axoloti is a development board that uses a Max/PD-like patching interface. It has an onboard 8-bit DAC which is 0 - 3.3v. Using a ‘dial’ I can control the DAC as seen in the picture.
Currently, when the dial is at max, the DAC output is 5.24v, but when I turn the dial down all the way, the voltage goes up to +10v. I want it to go the other direction to 0v!
So I’m halfway there, but how do I make the voltage go down instead of up when I reduce the DAC voltage? Thanks!
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I don’t think you are halfway there, since the +10V makes not much sense. You get 5.24V with an input signal to the non-inverting input of the opamp of 3.3V if it is built like you have shown above (more precisely 3.3V*(1+620Ω/1000Ω) = 5.25V), so I assume that 3.3V is on the non-inverting input when dial_2 is at max. If you get 10V at the output with dial_2 at min, this means that the input voltage must be 6.17V (via 10V/(1+620Ω/1000Ω) = 6.17V).
This however makes no sense since you said that the Axoloti development board has an 8-bit DAC which outputs from 0V to 3.3V.
My guess is that the circuit is wrong or the software does not what it promises 
Do you have some pictures of your setup?
Most importantly: have you measured the voltage at the output of the DAC respectively at the non-inverting input of the opamp? Do you see 0V and 3.3V when you set dial_2 to min and max?
Generally it’s always good to start from the input side and follow the signal path. Check all the components (correct values), measure them if in doubt etc.
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Thank you for your very detailed answer. You are correct, the op amp was connected to ground instead of negative voltage. 
One of those situations where I’m so dazed from trial and error that the simple things fall out of focus. This is awesome, full speed ahead!
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That’s how we learn, by making (tons of) mistakes. Enjoy your adventure and feel free to ask for feedback whenever you’re stuck again 
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