Page 151 - 15 Dangerously Mad Projects for the Evil Genius

Chapter 10 ■ Laser Voice Transmitter 129

Figure 10-10 Laying out the parts of the receiver

holes for the sound from the speaker and the light touching a flashlight to one side of it. Looking
sensor, and one small hole for the toggle switch. from the other side, you will see that the material
Drill the holes in the lid and gently file off any is all lit up, with the brightest area in the center.
burrs or rough edges in the plastic. The end result This effectively increases the target area that the
is shown in Figure 10-11. laser has to hit from the tiny size of the
phototransistor to the size of the hole in the lid.
Bare holes in the lid would look a little ugly,
and also require a direct hit on the phototransistor The material covering the hole for the speaker
by the laser, so let’s fix some material on the inside was simply made from some of the black
of the lid behind each hole (Figure 10-12). conductive foam that the IC was packaged in. You
could use any thin material that will let the sound
The diffuser is made from the same white
out unimpeded.
expanded plastic packing material we used in
Chapter 5. You can test its diffusing effect by

Figure 10-11 Figure 11: Drilling the box lid Figure 10-12 Covering up the holes