Actually using the DISPLAY_TIME to delay the colors.

The DISPLAY_TIME in circuit #3 is not used, even though it is mentioned in the comments (I guess it should be either deleted or used).

I also made a variation of the sample to use the potentiometer to manage the DELAY_TIME, and also to use a bitwise-based RGB function to improve the way the spectrum if shown. 

You can see it here: https://github.com/josea/SIK-Guide-Code/commit/7fc201848bdd9a4b8cdf6630a9d127b77b423ce1