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Have you finished the first handout your teacher gave you?

If not, go back!!!


Below are four examples of using logic switches to design something.  Follow your teacher's instructions for this page.


1.  A way to make an OR switch out of an AND switch and three NOT switches.  (Why would you do it?  Mostly just to see that you can create one kind of switch out of the others...it shows how they relate to each other.)


2.  Logic for anti-lock brakes in a car (which turns off the brakes for fractions of seconds until skidding stops)


(on = brake is on)

Brake Pedal

(on = pedal is pushed)

Skid Detector

(on = skid detected)




3.  Referee of coin flip at beginning of a football game (Visiting team makes the call)

Who Wins Flip

(on = Visitors win)

Visitor's Guess

(on = heads)

Result of Flip

(on = heads)





4.  A burglar alarm for a room with two windows, two doors, and a key switch to enable the alarm

Window #1

(on = window open)

Window #2

(on = window open)

Door #1

(on = door open)

Door #2

(on = door open)

Enable key

(on = alarm enabled)



(on = siren is on)


Description of the burglar alarm:

The alarm light will go on if the enable key is on and at least one of the doors or windows is open.  If the enable key is off, it doesn't matter whether doors or windows are open.  The alarm is off if the enable key is off.  The alarm is also off if the enable key is on, but all of the doors and windows are closed.





 2010 KnowledgeContext


Teaching Young People to Think About Technology