i want to make a dvm using 7107ic i have seen all the datasheet of this ic and make a schematic on proteus i have done the circuit calibration for full scale of 200v but i can not able to do the calibration of the circuit for 2000v for this I put a resistor across pin IN+ and IN- 120kohm but it show 199.9full scale, what i have to do.

and what is the process of selecting the range selector resistors and pot for calibration.

please help me

with regards
girish

 

Yes you need to make a Voltage Ladder at the input..

Here is a circuit for Ac, Dc voltage look at the voltage range switch, ignore the capacitors for DC.