"SMART" DOMINOS ACTIVITY - Build a domino run that's "smart" with electronic sensors and motors.

	Build a domino run that uses a copper switch to turn on a light (or a motor) when the last domino falls.
	Build a "smart" domino run that is controlled by a handheld programmable brick. Use switches and sensors to trigger events when dominos fall.

Things you'll need to do this activity:

* Before You Begin: This activity involves using a handheld programmable computer, the Lego RCX Brick. Powered by six AA batteries, the RCX can control three seperate motors and receive input from three sensors. Your class or organization may have access to a similar device called a cricket.

If you have the Lego RCX Brick, you also probably have some Lego switches and sensors (i.e. reflectant, touch, or temperature) - for this activity we're going to build our own switch using an old Lego connector, alligator clips, and thin copper strips (but you can use anything that will conduct electricity).

For programming, we're going to use Java-based software, developed by the MIT Media Lab, called RCX LogoBlocks. If you don't have the LogoBlocks software, the Mindstorms or Robolab software that comes with the brick is equally functional.

Step 1: Decide what you want to happen in your domino run - If you want to have a copper switch trigger a light to turn on, check out the directions in the marble machine activity. Instead of attaching the copper pieces to a ramp, you'll attach them to a domino. (see step 7 of this activity). If you have an RCX brick and want to make a "smart" domino run, keep going on this page.

First we need to make an alligator clip switch that will give input to an RCX brick. You'll have to sacrifice one of the motor connectors that came with you Mindstorms kit. The good news is that you can make two alligator clip switches out of one motor connector. (1) Cut the connector in half and (2) cut down the center of the wire splitting it into two seperate wires (2-3 inches down). Note: You don't have to make a switch like this, you can use any of the commercial Lego sensors/switches.

Step 2: (1) Strip the ends of the wires (both on the alligator clips and the connector). (2) Twist the wires together and wrap a small piece of electrical tape around the exposed wires - (or use heat shrink if you have it).

Step 3: Now let's build a switch that can be used to trigger something when a domino falls on it. We used a domino and taped two pieces of copper on either side of the domino. There are more switch examples below in steps 4 & 5.

Step 4: (1) Here's our finished sensor. It will lay flat like this and the final domino will fall on the copper pieces, causing them to touch - sending a signal to the RCX brick. Of course, you don't have to use copper as the conductor for your sensor, anything metal will work - (2) we had these little aluminum discs that also worked - try building something for them to hang from and are triggered when a domino knocks them together.

→ What else will conduct electricity? - anything that will carry an electrical current can act as a switch. Here's an example of a switch made using water as the conductor. The orange arrow points to a lever that, when a heavy domino falls on it, will pull the copper piece out of the water - BREAKING the circuit.

← Here's another example that involves breaking, rather than completing, a circuit. The metal ball conducts electricity until the domino falls - knocking the marble off and breaking the circuit. Hint: It can be tricky to get the marble balanced on the cardboard - try making a slight indent in the cardboard for the marble to sit on.

↓ Here's another example that involves using foam instead of cardboard to hold the marble.

Step 5: One problem that we encountered while building our project was that the last domino wasn't heavy enough to trigger the sensor (or knock the ball off). Our solution was to tape wights (such as coins or washers) onto the domino. Hint: Make sure you tape even weight to both sides of the domino or it won't stand up.

Step 6: We wanted to make our run more than just a bunch of dominos that fall and trigger a switch. So we built a (1) ramp out of cardboard and old bottle caps. We also wanted to automate the start of our run - so we built a (2) "kicker" out of Lego blocks, a motor and gears. Get creative - think about all the different ways you could automatically start a domino run. Your run doesn't have to be ALL dominos either! Check out the video in the next step to see how we incorporated a little motorized car into our run.

Step 7: Before we write a LogoBlocks program- let's take a look at our final project - watch a Quicktime movie by clicking on the picture to the right →

YOU NEED THE QUICKTIME PLUGIN TO VIEW THE MOVIE.

OTHER THINGS TO TRY:

→ Make a combination marble run and domino run!

→ Try using sensors instead of switches - how could you use a temperature sensor, or a reflectant sensor?

→ Think about other things that will conduct electricity, can you make an unusual switch out of something ordinary?

→ Get together as a group and make a giant chain reaction domino run!