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Birthday Cake
Building: Advanced
Program: Advanced

Building Instructions










Snap the groups of beams together in the order shown above (each group bottom to top).


Use the shortest wire to connect the sound sensor to port 2 on the NXT, and the medium wire to connect the motor to port A on the NXT.  Route the wires as shown below to keep them out of the way.


Before inserting the candle flame, rotate the handle on the motor to the vertical position, which should put the lifting arm on the inside in the high position.

Birthday Cake Programming

Use the Birthday_Cake program for the Birthday Cake.  This program takes a lot of memory in the NXT, so you may need to delete other programs and sounds before downloading it to the NXT.

How to Use the Birthday Cake
  1. Before running the program, follow the instructions at the end of the last building step above to position the motor arm in the correct position to support the candle flame.

  2. Run the Birthday_Cake program.  Make sure that the room is quiet so that you can hear the music and so that the sound sensor does not trigger accidentally.

  3. When the music finishes, you can blow the candle out.

  4. Before running the program again, turn the model upside down and remove the candle flame stick entirely, so that you can position the motor in the starting position again and re-insert the flame stick.


  • Try adding other decorations to the cake.  Maybe even some motorized decorations using the other two motors?

  • As written, the Birthday_Cake program makes you wait until the song is over until you can blow out the flame.  For a programming challenge, try modifying the program to allow the flame to be blown out at any time.

  • You know those trick candles that keep re-lighting after you blow them out?  With a little mechanical modification so that the motor arm does not drop the flame stick entirely, maybe you can modify the candle and the program to keep re-lighting it after you blow it out, and loop to let you blow it out multiple times.

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