This will allow you to see value 1=5V, 0=0V, or High Impedance. You should put the LEDs in such a way that both are on when the probe is disconnected. The green LED should be on when the probe is toched to the 0V or Ground wire, and the red LED should be on when the probe is connected to the 5V or +V supply wire.
Sign the lab sheet when your probe is working properly.
This so you could practice designing a circuit in Fritzing. The Or gates and And gates are not using the correct part number. I did this for clarity of the schematic. Fritzing does have a 74*32 and a 74*08 but I used the individual gate kind to make diagrams show the gate not big block.
