Transmitting voice over wires is a concept inherited from Bell's invention, the telephone. Today, there are a huge number of electronic devices that use the microphone to capture and transmit sound over wired networks, right up to a loudspeaker that has the ability to encode the signals and convert them back into sound. In this article, we will look at how to make a simple microphone.
– Plastic cylinder like the one used for photographic rolls.
– Three graphite sticks.
- A loudspeaker.
- A 12 V power supply.
Creating our homemade microphone
To begin our assembly, we take the plastic cylinder and pierce it with two graphite rods (we will have previously made a couple of holes), we fix them well, so that they protrude well above the plastic cylinder.
The next step is to wire up our microphone. To do this, we connect one of the graphite rods to one of the poles of the power supply, while the other graphite rod will be connected to one of the inputs of the loudspeaker.
Now, we must place a wire between the free pole of the power supply and the speaker. In this way, we will close the circuit and we will almost have our homemade microphone ready.
Next, we place the third graphite rod between the first two rods perpendicularly, allowing the three rods to be in contact with each other and keeping the circuit closed.
The only thing left to do is to experience it. To do this, we will speak close to the microphone and we will be able to hear how the voice is amplified in the loudspeaker.
How it works
The operation is quite simple, when speaking close to the microphone, the sound waves reach the perpendicular bar and a pressure variation is created and transmitted through the graphite rods, creating an electrical resistance based on Ohm's law (V=I*R). These changes reach the loudspeaker in the form of electrical impulses which are again encoded as sound waves.