Anyone can explain the "digital voltmeter" circuit to me?

[ee1874]

On positive of input, what use for the chooice of different path of resistor?
Why the first resistor is 10ohm, then suddenly to 1k ohm and suddenly to 100kohm? Why not use 10k ohm for second and 1k ohm for first?
How to know the 10ohm is for range 200mV and same for 1k,100K,1M,10M, how to know their voltage range? Got formula to calculate it?

On negative of input, what use for the adjustable resistor ? Can eplain more detail about the function of the ajustable resistor?

Can explain whole circuit to me?

 

[audioguru2]

Hi EE,
Welcome to our forum. ;D
The ICL7107 IC has a very high input resistance. The range switching for a voltmeter that uses it should use very high resistor values.

Our projects don't.

Our "Digital Voltmeter" project uses a 10 ohm resistor in series with the input on one scale, then a 2k pot to ground. Rediculous!

Our "LED Display Digital Voltmeter" project uses a 0 ohm dead short across the input to the IC on one range. Rediculous!