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You can see the finished pumpkin in Figure 9-1.

Here’s the big picture of this pumpkin project:

1. Put together two electronic circuits and fit them into plastic pumpkins
   with switches, a microphone, and a speaker.


2. Use a microphone to record a sound or message.
   We like, “Welcome to Sleepy Hollow. We hope you have a good time,” fol-
   lowed by a spooky laugh.


3. One pumpkin transmits an infrared beam to the other. When someone
   walks between the pumpkins, the recorded message is triggered, along
   with a flickering red light.


4. To reduce the chance of this IR noise interfering with your gadget, use
   an IR detector tuned to detect infrared that turns on and off at 38 kHz
   and ignores infrared not switched at that frequency. The transmitter cir-
   cuit then sends out infrared that is switched on and off at 38 kHz, and
   the noise problem is solved.

One complication you’ll deal with along the way is lots of infrared noise

floating around. IR is given off by heaters, people, pets, and pretty much

any living creature or equipment that gives off heat.

Figure 9-1:
The final
product: a
talking
pumpkin.

Part III: Let There Be Light .......................................