Lowering DC voltage without using a voltage divider

[IN0RAN]

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 

[KJDS]

http://www.eetimes.com/document.asp?doc_id=1272269

[Supercharged]

If you need a high impedance input try this (see picture). Its a basic design but it'll do the job. (sorry for the crude drawing)

[max_torque]

If you need a high impedance input try this (see picture). Its a basic design but it'll do the job. (sorry for the crude drawing)

Won't the op amp power rails have to include(exceed) the 40v measurement potential??

[Supercharged]

If you need a high impedance input try this (see picture). Its a basic design but it'll do the job. (sorry for the crude drawing)

Won't the op amp power rails have to include(exceed) the 40v measurement potential??

Yes but you can use two seperate power rails for the ADC and for the Opamps.

[Kleinstein]

The circuit should also have some extra compensation for the upper OP. Just standard OPs might very well start to oscillate, as the upper OP sees extra amplification inside the feedback loop. So use something like a resistor at the output of the lower OP and a capacitor in feedback at the upper OP.

[Supercharged]

The circuit should also have some extra compensation for the upper OP. Just standard OPs might very well start to oscillate, as the upper OP sees extra amplification inside the feedback loop. So use something like a resistor at the output of the lower OP and a capacitor in feedback at the upper OP.

I agree, my design is just a basic concept and should be tested and improved.

[IN0RAN]

http://www.eetimes.com/document.asp?doc_id=1272269

Thank you for this , I wasn't aware of the errors associated with measurements that used a voltage divider.