Backyard Aquaponics
A place to discuss aquaponics

you could also use a pwm with a filter to create a dc voltage. Then you have a high resolution fully variable gain op-amp
Actually thats what I am working on now for a project. I am using a pwm output to generate an analogue value. Basically I am making a waveform generator which is effectively a music player.

so are you using this circuit in your scope ?
Working well ?

Yes and Yes.
The 5% tolerance (of the resistors) is a pita, but as I never intend to make more that 1, it's only a pita until it's calibrated.