ICL7107 Voltmeter calibration

1

123mmm

Member

• Jan 2, 2021

• #1

Hi, I need some advice regarding the attached schematic. I built the schematic, it is working but I don't know how to calibrate it. I need to measure between 0 V and 50 V.
I set the Rx1= 100R and Rx2a= 100k, but if I rotate R4, then the displayed value modifies.
Do I need to calibrate it using a standard voltmeter ?

 

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D

Diver300

Well-Known Member

Most Helpful Member

• Jan 2, 2021

• #2

Yes.

However, you could just measure the output of the 7805 which will be within 2 % of 5 V.

 

K

KeepItSimpleStupid

Well-Known Member

Most Helpful Member

• Jan 2, 2021

• #3

Your options are as follows. Calibrate the 200 mV range and let the resistors to their thing. e.g 1%, 0.1% etc,

or calibrate near the nominal voltage you need to measure accurately. e.g. inject 25V and calibrate to 25V.

A calibration source is usually better than your meter. It might be a 2.500 V source.

 

1

123mmm

Member

• Jan 2, 2021

• #4

The calibration should be as follows.
1. Set the values for Rx1 and Rx2a
2. Set the displayed value by rotating R4 ?

 

D

Diver300

Well-Known Member

Most Helpful Member

• Jan 3, 2021

• #5

123mmm said:

The calibration should be as follows.
1. Set the values for Rx1 and Rx2a
2. Set the displayed value by rotating R4 ?

Click to expand...

That's correct.

You do need some voltage reference that is a known value to calibrate against.

 

gophert

Well-Known Member

Most Helpful Member

• Jan 3, 2021

• #6

https://airborn.com.au/circuits/mas830l.gif

 

S

shokjok

Member

• Jan 4, 2021

• #7

Please translate the warning at the bottom left of the schematic.

 

1

123mmm

Member

• Jan 4, 2021

• #8

Hello shokjok , the text is this:
FIGYELEM!! A 2000V csak egy elméleti határ.
Eszébe se jusson senkinek kipróbálni!
Using google translate:

 

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