So I have recently started my first group project, which is to design an autonomous hovercraft. We decided to drive the propulsion fans (which are rated at ~7 V and our battery runs at 12 V) using a TIP120 transistor.
We found the design online and it seemed to match our situation, so we used it. The problem is that when we connect the battery, the fans do not turn on. I made a quick picture of our circuit:
The original circuit that based ours on is found here.
Is there a problem with the wiring, or did we pick out the wrong transistor?