MacGyver Season 2 Episode 12 Science Notes: Jack + Mac

Photo: Rhett Allain. Diagram showing the workings of a photophone.

Before I get to this science for this episode (there’s some awesome MacGyver hacks here), let me say something else about the show. The storyline for this episode was great. It had a nice plot, and I really enjoyed the MacGyver and Jack flashbacks. Now for some science.

Photophone

The best Mac-hacks are real. This is real-very real. It is indeed true that this was an early idea for a phone. Here’s how it works.

• You need a directed light. One way to do this is to get a mirror that reflects sunlight. A parabolic mirror works a little better, but still the mirror is a great idea.
• Use your voice to shake this mirror. This changes the intensity of the reflected light to match the wave pattern of your voice.
• Use some type of electrical photo device (solar panel, photo diode, photo resistor) to modulate an electric current to this same sound pattern from the light. Send this to a speaker.
• That’s it.

For MacGyver’s build, he uses a microphone and connects it to a porch light. The idea is that the microphone will modulate the brightness of the bulb. For this to work, I think it has to be an LED bulb. An incandescent won’t work (I don’t think) since the hot bulb filament won’t change brightness quickly enough…