Last updated at 09:13 AM on 02 Nov 2011
Class meeting on 24, 25 October 2011
One way to study for the midterm is to review the Learning Objectives for each lecture that are posted on this web page.
The Wikipedia article on flyback diodes explains how the flyback diode prevents unwanted reverse current surges when a circuit containing an inductive load (like a motor) is interrupted.
The manual for the Sparkfun Inventor's Kit calls for a 10k resistor to connect the Arduino motor pin to the base (middle pin) of the transistor. I found that the voltage drop between the digital output pin and the base was too great, which meant that the transistor did not change state and allow current to flow from the 5V supply to ground. The circuit did work when a 330 ohm resistor was used instead.
The modernmechanix.com site has [a short article from the 1953 Scientific American with the title Transistor -- mighty mite of electronics