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How to calibrate full scale o/p range of ICL7107 (ADC)?

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henry77

New Member
Hello Friends,

I have built a DC voltmeter with intersil ic ICL7107PCL. Maximum full scale output possible with it is 2V. I want to measure voltages upto 50V, so how can i do it? Can anyone suggest me kind of attenuator section which can be used at input or any other way i can measure upto 50V? I have used following circuit provided in datasheet

https://www.electro-tech-online.com/custompdfs/2009/11/fn3082.pdf

Please help me with this issue.

Thank you all.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
It's VERY simple - to drop 50V down to 2V you need to drop 48V across the top resistor of the attenuator, and 2V across the bottom one. So they need a ratio of 48/2 (or 24/1).

A 24K for the top and 1K for the bottom would do.
 

henry77

New Member
Hi Nigel,

by using 24K and 1K resistor we can scaled down voltage in the range of 50-3V to 0-2V, but when i feed this voltage to ADC it displays voltage in 0-2v range.

My question is how can i change scale of the ADC, so that it displays voltages in the range of 0-50 Volts?

Please reply.

Thanking you
 

mneary

New Member
My question is how can i change scale of the ADC, so that it displays voltages in the range of 0-50 Volts?
You scale the input down 100:1 so you get 0-0.5V and move the decimal point.

The 7107 only will display 0-1999.
 

henry77

New Member
Hi mneary,

Thanx for your help, its working fine now. I used a voltage divider n/w to scale down the i/p, and it displays the i/p fine now.

Thanks again
 
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