the first part of this week in pcomp was the transistor lab.  i hooked up everything and than supplied an external power source using my DC adaptor to supply to my DC motor.  however.  i think i must have wired something wrong because although it did work at one point, the next time i plugged in my arduino, it stopped responding and the software said that the programmer has stopped responding and the L LED light no longer lights up!  ah!