A/D Converter Simulator
 
        Here is the circuit.

Here is how the A/D Simulator works.

• First, set a DC voltage from the adjustable source.
• Second, click the "Convert" button.
• The counter begins counting, and the count is displayed on the LEDs and the numerical value of the count is displayed.
• The digital count signals (four bits of signals in this case) form the input to a D/A converter which produces an output voltage proportional to the count.
• The output voltage from the D/A is compared to the input voltage.
• When the output voltage from the D/A becomes larger than the input voltage the comparator develops a "Stop" signal that is used to stop the counter.
• The count that remains in the counter is a digital representation of the input voltage.

Try the simulator, using different voltages within the allowable range, i.e. 0-5v.  Then check what happens when the voltage is out of range.