How I built a logic probe

Today I built a logic probe.  I followed the handout from Prof. Mason's Mechatronics class entitiled "Build a Logic Probe".  These are the components:

This is the probe touching +5 volts (logical 1, TRUE).  The LED is bright.

 

This is the logic probe touching nothing.  The LED glows dimly..

 

 Here the probe touches 0 volts (logical 0, FALSE, common, ground).  The LED is dark.

 Bottom view of the assembled probe.  A drop of hot glue was added later to hold the power clips to the board.  The probe is made from a paper clip.

 Top view of the assembled probe.