Implementation: Harvest USB Cable from broken keyboard, find power/ground on their connector to avoid needless bare wire, secure banana terminal and switch to case, hook up the power to switch/banana, Hook up LED/Resistor to internal banana to indicate power status. Very much like building a ship in a bottle.
Possible upgrades:
Because I kept the usb connector, it still has the data pinouts, these might be utilized for a future project. Possibly upgrade my gaming headphones (also built from scrap parts). Currently uses any USB port or charger, might add some kind of fault protection later.
Needed upgrades:
While I've always been careful about faults, it's been brought to my attention that this circuit needs some form of fault protection such as a fuse or a resettable breaker to be used by anyone else. The breaker idea seems most promising, so if the cost is reasonable I plan to implement that soon-ish. Then, assuming all works well, I'll make a few to keep around the electrical engineering lab. This way future students in the digital series will be able to work on circuits from home as well.