Hey guys! I have project where I have to measure voltage from a 40VDC (max) source using an acquisition device that has an input limit of 5V. So far, the only viable solution I've come up with is the attached image, a voltage divider and a buffer for isolation. But I want to know if there's any other solution that I can build (so, no DC-to-DC converters).

Thank you in advance

PS: I know this is a good and easy solution, but I'd like to know the alternatives, if there's any. It's just me being stubborn for the sake of learning

 

That's the simplest solution
You could use a switched capacitor circuit to do the same thing but that's much more complicated.