Digital Volt Meter: Setting Reference Voltage & Input Voltage

[cscott]

This circuit was used to make a digital volt meter. What I'm confused about is the exact use of the potentiometer on the RHS of the diagram. I know is was used to set the "reference voltage" to 4V and all all output voltages from the meter would be from 0-3.999 volts when displayed. The potentiometer on the LHS is varied to change the input voltage.

[img=http://img395.imageshack.us/img395/3872/71369663pz9.th.jpg]
[img=http://img291.imageshack.us/img291/4333/68711262rj5.th.jpg]
Thanks

 

[cscott]

Get it now, nm

 

[berkeman]

This circuit was used to make a digital volt meter. What I'm confused about is the exact use of the potentiometer on the RHS of the diagram. I know is was used to set the "reference voltage" to 4V and all all output voltages from the meter would be from 0-3.999 volts when displayed. The potentiometer on the LHS is varied to change the input voltage.

[img=http://img395.imageshack.us/img395/3872/71369663pz9.th.jpg]
[img=http://img291.imageshack.us/img291/4333/68711262rj5.th.jpg]
Thanks

Well since you get it now...

Quiz Question -- what specs would you check on that IC to be sure that its connections to the potentiometers were done correctly? What could potentially happen if a certain spec on those two pins weren't what you wanted?