Step 17: Insert the Photocell
Insert the other pin of the photocell just above the center pin of the second transistor (the one more towards the front of the SpurtBot).
Pinch the two leads of the photocell slightly, being very careful not to let them touch each other. Then take a piece of 3/16 inch shrink tubing about ¾ inch to 7/8 inch long, and place it over the photocell.
This will prevent stray light from interfering with the operation of the photocell.
Note: If you find the SpurtBot is not sensitive enough to light during testing, even after adjusting the potentiometer, you can trim the length of the shrink tubing so that the photocell is closer to the opening. You want to keep the photocell lower than the top edge of the tubing. Don't cut it now, wait until testing.