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The Learning Circuit 46: Introducing Microphones and Speakers

Introducing Microphones and Speakers

The Learning Circuit | element14 presents |  Project Videos

 

 

Time to learn about electronics that produce and interpret sound. But before getting into the electronics, it’s good to first understand how sound works. When a sound is generated, a vibration is produced that pushes and vibrates the surrounding air which continues and is carried through the air until it reaches our ears or other devices that can interpret sound.

 

 

 

Speakers are electronics that generate sound. The two main types are dynamic, which use permanent and electromagnets to vibrate a diaphragm, and piezoelectric, which use electrically charged plates that bend and flex when a charge is introduced or removed. It’s all about those good vibrations.

 

Did you know that a microphone is basically a speaker working in reverse? You can even take a set of headphones and use them as a microphone. Try it some time with a set of earbuds. Since microphones are essentially speakers, they use the same types of technology to interpret sound, magnets or piezoelectric. Note from Karen: “Doing research for how things works are always extra fun when it involves taking things apart. One of my favorites was taking apart the tiny DC motors to find the little lamination and magnets inside, but speakers were a close second. It was interesting to see the slight difference between different models. And with small speakers, I couldn’t always guess whether it would use a piezo or magnets. If you’ve got a solid rotary tool handy, I highly recommend taking your components apart to see what’s inside. You might be surprised by what you find.”

Anonymous

  • Hi Karen,

     

    A well done presentation. I thought that the graphics were excellent. Years ago there were also piezo microphones that worked by having a diaphragm vibrate a small piezo crystal. They were also called crystal microphones and were often used with inexpensive tape recorders. The frequency response favored the higher frequencies do they often sounded tinny. Most of the time they had a fairly rigid aluminum diaphragm. The microphone element in the desk microphone that you had open in the presentation reminded me of a piezo element.

     

    John

  • Occasionally you will come across a dynamic microphone which does require power as some have pre-amps built into the microphone.

     

    The Blue 'Ball' mic was one of the first which I encountered:

    https://www.soundonsound.com/reviews/blue-ball

     

    For those interested in using microphones in a real world environment, then there is quite a good webinar presented by Chuck Espinoza / AVIXA titled 'Balancing Audio Systems' here:

    https://players.brightcove.net/1125650858001/Hk4Wwu8pb_default/index.html?videoId=5764805457001

  • Very good episode.

     

    You did a good job of showing how a microphone and speaker work and how you can under some circumstances interchange them.

     

    I once worked on a project where we replaced the speaker coil with stepper motors so that we could simulate the air pressure wave of a sonic boom.

     

    DAB