digital voltmeter and temp display

[Elven Commander]

Hi all,

I've been doing some thinking lately, and have a few more questions.  I looked into the ICL7107 that was suggested and is used in the voltmeters on this site. 

  What does "an internal voltage reference" mean?

  I found myself the 7107 datasheet, and still unsure about some stuff.  I know how to connect up my display units etc.  I will be using a thermister to find the temperature. 

  I was looking at the Led display digital voltmeter in the projects section.  According to this the input goes in threw the 1 and the 2.  It passes threw 2 resisters and a capacitor.  R4 on the diagram, I could just put my thermister here in place of R4.  All I would have to do is hook up power to it and it would measure the voltage.  This is my understanding, am I close to the mark?

If I am correct, the one thing that was eluding me, how does it compare a voltage that it recieves and knows, that hey, that there is = to 30

 

[MP1]

Internal voltage references are used for comparison to the input data. This is how you would scale.

The meter is actually displaying 30 volts or 30 millivolts, etc., depending upon your scaling. It is not actually reading a temperature. You adjust the high and low for the meter as a calibration. In other words, you add an adjustment to pin 36 to adjust the voltage for a high calibration and you add a voltage adjustment to the input or pin 31 for a zero scale or low end adjustment. BTW- The input is not on pins 1 and 2, it is at pins 31 and 30. Where did you see this?

MP