Most microphones work the same way. They have diaphragms that vibrate when sound strikes them. The energy from these vibrations converts to electricity that travels as an audio signal. When the signal reaches a loudspeaker, the loudspeaker converts it back to sound. Today, we are going to make a battery microphone with a pencil and a matchbox.
Materials For Microphone with Pencil Lead Diaphragm
- The drawer part of a matchbox that holds the matches
- Two black pencils: Look for #2 HB with medium hardness
- A fresh, nine-volt battery still well within its sell-by-date
- Three insulated wires with crocodile clips at each end
- A pair of old cellphone earphones you no longer need
How To Make a Battery Microphone With Matchbox
Empty a matchbox and discard the matches and the sliding part. Make two holes you could just push a match through in each drawer end about a half inch apart. Then carefully split the pencil in the length following the instructions in the video, while preserving as much of the graphite core as possible.
Before proceeding further scrape a flat surface along the graphite using the blade of a pair of scissors. Gently prize out the core. Now break off two pieces of the pencil lead approximately one inch longer than the matchbox tray. Slide these ‘microphone terminals’ through the holes at either end of the matchbox drawer so the same amount protrudes at both ends. Make sure the flat surfaces are facing up. This almost completes the steps to make a battery microphone diaphragm.
Snap off a third piece of the pencil lead almost as wide as the matchbox drawer. Position the flat side across the other two pieces of the diaphragm a quarter inch away from one end. To make the connections with the three insulated wires:
- Connect a nine-volt battery terminal to one microphone terminal
- Join the other battery terminal to one headphone contact
- Connect the headphone contact base to the other battery terminal
Tap the microphone diaphragm gently with the other pencil. You should hear the sound through one of the headphone speakers. You know how to make a battery microphone. Now watch the video to learn how to transmit the sound to another room.
Preview Image: Matchbox
Video Share Link: https://youtu.be/yj-wkw98j7Q