Physical Computing Week Eight Lab: Transistors and H-Bridge

Again, a bit late with this one, but better late than never.  In week eight of Physical Computing, we investigated the use of two slightly more complex devices:  the transistor and the h-bridge.

The transistor lab consisted of attaching a transistor to a small motor, and controlling the voltage output to the motor via the transistor.  This differs from a typical input/output in that the transistor can accept a far higher voltage than the arduino microcontroller's 5 volt power supply.  As such, the arduino can still be used to control a device that requires a much higher voltage.  The circuit with the motor can be seen above, while a video of the on/off control can be seen below.

The h-bridge lab consisted of using an integrated circuit known as an h-bridge to control the direction of current.  Put differently:  the motor from the first lab will run in different directions, depending on which way it is wired in the circuit.  The h-bridge allows us to select which direction of current we prefer, thus allowing for a single wiring scheme for the motor, but allowing us to decide (via a switch) which way we'd like the motor to rotate.  You can see a photo of the circuit above (the h-bridge is in the center), with a video of the bi-directional motor control below.