High voltage measuring with ADC

[fuzzzy]

measuring high voltage adc

Hi,

I didn't find useful answer to my problem in this forum, so I ask you.

I have a ADC from National Instruments measuring voltage from 0V to 10V single ended.
I need to measure voltages from 0 up to 120V . could you please suggest me a good circuit to convert and measure with precision this voltage?

Thanks a lot for your help

 

[budhy]

Use this simple resistor voltage divider:

 

[roykyn]

use an opamp like tlo82 after the divider network.....it isolates the circuits i/o and o/p

 

[fuzzzy]

i used this solution you suggested. but i don't think it's very exact.it need calibration. don't you think?? i'd like to avoid it.


thanks

 

[echo47]

budhy's design is accurate if your ADC's input impedance is much much higher than R2. If it isn't, then you can change the resistor values to account for the ADC's input impedance, or you could add a high-impedance opamp buffer as roykyn suggested.

If you are measuring high frequency, you may also need a small compensation capacitor across R1. The value depends on your wiring capacitance and the input capacitance of your ADC (or opamp buffer).