Introduction: Simplified Electronics: Microphone (DIY& How It Works)
So I have decided to create a new series of videos and instructables where I choose one electronic component we use everyday in our lives in electronic circuits, and I will give an overview of their history, how they work and how to make them yourself. Some of my explanations might have mistakes, and I apologize if I misdirect anyone into learning something incorrect. But on the other hand, I have to research on those electronics myself to write these instructables, and thus it will be helpful in educating myself. I hope you will also learn something from my instructable. Also most of the explanations in this instructable will be done with simple words and analogies, because that's what I am capable of. If you find any mistakes, please do correct me.
The instructable is divided into many short steps to make sure it is super simple to follow.
If you don't want to see some steps, just skip them. The steps are divided in the following order:
1) Step 1: Watch Video!
2) Step 2: What is a Microphone?
3) Step 3: History of Microphone.
4) Step 4-7: How do Microphones work?
5)Step 8: Pros and Cons of different types of Microphones.
6) Step 9-21: Building the Microphone.
. - Step 9:Material
. - Step 10-15: Making the Diaphragm and Coil.
. - Step 16-20: Building the base, and putting the Microphone together.
. - Step 21: Testing the Microphone.
7) Step 22& 23: Troubleshooting tips and finishing words.
Now time for some warnings, cause why not. I am not going to show you how to make a studio quality microphone. You could barely hear my voice in the microphone, so needless to say it isn't really useful in real life uses. But that is not point of this build, in fact the main point of the build is to familiarize with the basics of Microphone. Also the explanations and history about Microphone that you are going to read in this instructable will not match the quality of something by a professor. Just leaving this as a warning, because a lot of people raise their expectations too high to be disappointed too much with anything I make or show. Also I am a high school student, not a Graduate in electronics major, so I am bound to make mistakes, and I would definitely be happy if you help me correct them.
Also a lot of the images are collected from online ( The animations are made by me, using a software called Anime Studio).
Anyway now that the warnings are laid forth, let's keep moving.
Step 1: Watch the Video!
Most of the things in the video is covered in this instructable, but if you prefer watching videos over reading then watch my video! I hope it will be helpful to you in some way. Also watching the video on youtube will increase my youtube views and maybe my funds for my future projects, so give it a go!
Step 2: What Is a Microphone?
So first of all what is a microphone?
It is a transducer device that converts Sound Waves into Electrical Signal (Audio Signal).
What is a transducer?
It is a device that converts one form of energy into another form of energy. Pressure sensors, light bulbs, speakers are all examples of transducers, since they all convert energy from one form to another.
So how does microphone classify as a transducer?
Microphones also convert energy from one form to another, since it converts the energy in sound waves to electrical signal. So it is a transducer. Most microphones output an electrical signal where the changes in the electrical signal correlates to the changes in sound wave that the microphone receives. The microphone can achieve this task through various different means, for example, through electromagnetic induction, changing resistance, changing capacitance and such. But all of these different types of microphone have one thing in common, the sound waves travel through a medium to hit the diaphragm which causes the diaphragm to move and in turn this movement causes a chain of events that leads to an electrical signal to be present at the output.
Also the schematic symbol of the microphone looks like a line attached to a circle from which two pins are coming out.
Also the the first two images are actually GIFs.
Step 3: History of Microphone
Alright, the history of Microphone seemed pretty complicated to me so I had to simplify most of it. Multiple sources reported multiple different information, and some completely contradicted the other. So here's the information I picked as the most plausible. And also if you are confused about some of the explanations and names of microphones here, worry not. I will explain more about some of those microphones and functions later on. I will mark the microphones that I am going to describe in details with four stars ****.
Microphone was created to satisfy the need of communicating over a distance. In ancient times, acoustic megaphones were used to amplify the voice of the speaker to speak to audiences that were far away. Later on a simple instrument named the 'Lover's Telephone' or 'Tin Can Telephone' was invented by Robert Hooke. Tin cans were simply two tin cans with a metal wire connecting to their bottoms. Sound waves would vibrate the bottom of the can or the diaphragm, and eventually the vibration would travel through the wire to the other can and reproduce the sound. Even though for the first time it allowed to transmit voice over a distance through a medium other than air, it was still extremely short ranged. The vibrations got weaker and weaker as the length of the wire became longer, and it became almost impossible to hear beyond a short distance.
Around 1870s, when telegraphs were transferring electrical signals and messages throughout the cities, different inventors started investigating ways to convert sound into electrical signal to be transmitted through the wires. Alexander Graham Bell known commonly for inventing the Telephone were one of the inventors who found success in converting sound into electrical signal. He created a voice transmitter that had a diaphragm connecting to a pin that was submerged in water. Sound waves would cause the diaphragm and pin and water to vibrate, and the vibrations in water would cause a varying electricity to flow through the wire and send the voice across. However Emile Berliner in 1876 created the Button Microphone which was far better than the liquid transmitter used in Bell's telephone. If you look at the third picture, which says Bell-Berliner system, you could see Berliner's transmitter or microphone on the left. Bell and Berliner had gotten involved in a lengthy legal dispute over the patent. But since Berliner's Microphone produced better results, the patent was issued under his name, and Bell's company bought the patent from him for $ 50,000. That's why the Berliner's microphone was incorporated into the telephone.
In 1878 David Edward Hughes invented the Carbon Microphone****. It however was not patented to his name, since the Carbon Button Transmitter patent was won by Thomas Edison in a lengthy dispute between Edison and Emile Berliner.
In 1917 Christopher Edward Wente invented the Condenser Microphone****. Condenser is a word that is used to refer to capacitors, and the Condenser Microphone utilized the principles of capacitance to function.
In 1923 Captain H. J. Round created the Moving Coil Microphone**** or the Magnetophone. It used electromagnetic induction in contrast to the method of utilizing changes in capacitance or changes in resistance to convert sound waves into electrical signal like the previous microphones. Today we know this microphone as Dynamic microphone, the ones we commonly see on stages. The same year Harry F Olson invented the Ribbon Microphone****, which also utilized principles of electromagnetic induction. However unlike previous microphones, it proved to be miles ahead in terms of sound quality and clarity. Soon after its introduction, the Ribbon Mic became the microphone of choice for studio recording.
But even then, no one could have imagined to have microphones such widely available as it is today. Microphones back then were bulky, expensive and generally not suitable to be incorporated into everyday electronics. Everything changed when the fire nation attacked. :) :) :)
In 1964, inside the Bell Laboratories, Gehard Sessler and James West invented the electret microphone, which was a type of condenser microphone. It didn't need a high voltage source anymore (Condenser microphone typically needed high polarizing voltage), instead it could work with a pre-amplifier. Also it was possible to make Electret Microphones tiny, tinier than anyone ever could have imagined before. It completely revolutionized the Microphone Industry, since it's inexpensive price tag and easy manufacturing made it widely available, and it's tiny size made it easier to incorporate into electronics.
Nowadays microphones can be found anywhere, and is cheap enough to include in almost any cheap circuits.
Step 4: So How Does It Work? Carbon Microphone
The primitive carbon microphones had four main parts, the power source, the output, the diaphragm, and the carbon. The designs have changed quite a bit since then, however those four parts remained in every design.
The digitally drawn diagram is a representation of a simplified carbon microphone. A diaphragm made of thin flexible film sit at the front or top of the mic. Connected to that diaphragm is a metal plate. A wire runs from the power source to the metal plate. And a bunch of carbon granules stay in contact with the metal plate. Another metal plate stays in contact with the carbon granules on the other side, and a wire from the metal plate runs to the output. So usually, there will be a stable electric flow through the power source to the metal plate to the carbon granules then to the other metal plate and finally to the output.
However when sound waves hit the diaphragm, the diaphragm begins to move back and forth extremely fast. When the diaphragm moves the metal plate moves back and forth, compressing and decompressing the carbon granules in the process.
Time for a bit of simple physics. Every material has some resistance, and the resistance of an object can be found by using the equation Resistance= Resistivity (Length/Cross section Area). The resistance across two ends of an object is directly proportional to the length of the object. If the length of the object increases the resistance increases. Alright now back to the microphone.
When the diaphragm is hit by sound waves, the metal plate moves, and the carbon granules compress and decompress, or in other words their length changes. As I mentioned above, when you change the length of a material, the resistance changes. The same happens over here. When the carbons compress the resistance decrease, and when the carbons decompress the resistance increases. And if you know about, V=I/R, you will know that the current at the output will be changing whenever the resistance of the carbon changes. And the changes in the current will be related to the sound the diaphragm receives. And that is how sound is converted into electrical signal in a carbon microphone.
Step 5: So How Does It Work? Condenser Microphone
I mentioned earlier that the term 'condenser' is also used to refer to capacitors. Capacitors are often extremely simple in design. Capacitors are made of just two conductive plates separated by an insulator or Dielectric material. The equation for the capacitance of a parallel plate capacitor is Capacitance= (Electrostatic Constant* Area of the Plates)/ Distance between the plates. So the distance between the two plates is inversely proportional to the capacitance of a parallel plate capacitor. Keep this point in mind.
So if you look the simplified diagram of a condenser microphone, you will see there is a diaphragm or a flexible metal plate in the front, and right behind it is attached another metal plate. They are insulated by the air between them. If you remember, capacitors are just two metal plates separated by an insulator. This microphone, also has a two metal plates (Flexible metal diaphragm, Back plate) and an insulator separating them (air). So this front is basically a simple capacitor. Now connected to the diaphragm is a wire that runs to the resistor and output. The back plate is connected to a battery, which then connects to the resistor and output. Normally a stable electricity will flow through the output.
But when sound waves hit the diaphragm, it begins to move back and forth, and the distance between the diaphragm and back plate changes. If you don't remember, the distance between the metal plates is inversely proportional to the capacitance. So the distance between the plates decrease the capacitance will increase and vice versa. So when sound waves cause the diaphragm to move, the capacitance of the 'capacitor' also changes. And because of this changing capacitance, the voltage across the resistor also keeps changing, and you get an electrical signal at the output that correlates to the sound hitting the diaphragm.
Step 6: So How Does It Work? Moving Coil Microphone
As the name suggests, a moving coil microphone is made up of a Moving Coil, placed near a Magnet. If you look the simplified diagram, you will see that attached to the flexible diaphragm is the Coil of Wires. Near the coil of wire is a permanent magnet, which stays in place. The wires from the coil runs to the output.
When sound waves hit the diaphragm the diaphragm begins to move back and forth, and so the coil also begins to move back and forth on top of the magnet.
According to Faraday's Law of Electromagnetic Induction, when a coil of wire moves through a magnetic field, a changing electric voltage is induced across the coil of wire. That's how most turbine generators work, they have coils of wire moving around a magnet, and they produce electricity through the process. Similar to that, in a dynamic or moving coil microphone, when the coil moves through the magnetic field of the magnet, an AC voltage or changing electricity flows to the output. This changing electric signal corresponds to the sound the microphone receives.
Step 7: So How Does It Work? Ribbon Microphone
Alright so the final type of microphone that I am going to talk about is Ribbon microphone. It is extremely similar to a dynamic microphone which works through electromagnetic induction. Instead of a coil, in a ribbon microphone there is a thin metal or a 'ribbon' placed between two magnets. When sound waves hit the ribbon it begins to move back and forth between the magnets, and an AC electricity flows out of the output. And thus audio is converted to electrical signal in a ribbon microphone.
Step 8: Pros and Cons of Different Microphone
So here's a bunch of pretty non-scientific pros and cons of the different types of microphones that I talked about so far.
Step 9: Let's Make the Microphone! Materials List.
Now that we are done with the explanations and stuff, we can move onto actually making the microphone. I am going to show how to make a moving coil microphone. Carbon Microphones, Ribbon microphones are also pretty easy to make, and home made ribbon microphones could actually record amazing sound, but to me Moving Coil Microphone was the easiest to make, so that's what I will be showing how to make.
Just a warning in case you missed it earlier, *DO NOT EXPECT GREAT QUALITY RECORDING FROM THIS MICROPHONE.*
Alright, so to build the microphone you will need the following materials:
1)Tissue Paper Roll. (You could just a roll a paper into a cylinder if you don't have tissue paper roll.)
2)Craftsticks. (It's to make the base of the microphone. Anything can be used instead.)
3)Wooden Cubes. (Once again, you could substitute it for other things such as a spring or cardboard. The wood cubes will hold the diaphragm)
4)Paper Cup. (We are just going to use the hard paper from the cup, you could cardboard instead of a cup.)
6)Magnets. (Neodymium magnets work great)
7)Thin enameled copper wire. Gauge 26-32 is a good range. (If the wire is too thick the coil would become to heavy)
8)A 3.5 mm Female Headphone jack. (My microphone would require a two headed 3.5 mm male headphone jacks to connect the microphone to computer. However if you want, you could use a 3.5 mm male headphone jack instead of the female headphone jack I used. It would make it easier to plug and record.)
Some tools you will need:
3)Sandpaper or something to scrape insulation from the wires.
4)Hotglue gun (optional)
So let's get to the build!
Step 10: Making the Moving Coil
Alright, so firstly we are going to make the moving coil part of our microphone.
Take a tissue paper roll, and mark one inch from the end.
Cut the 1 inch cylinder.
Poke a hole on one end of the cylinder.
Step 11: Making the Moving Coil (Part 2)
Take a thin enameled copper wire, and insert it through the hole of the cylinder we cut out earlier. Pass two to three inches of wire through the hole. This extra wire will act as one of the ends of the coil.
Now start coiling the wire around the cylinder. Coil the wire 150-200 times around the cylinder. Make the coil as neat and tight as possible. Use nail polish or tape or glue or anything you want to keep the wire in place, and trust me, you don't want the wire to come loose after coiling halfway.
After you are done coiling, leave about 2 to 3 inches of wire in the end again. Now use hotglue to secure the coiling, so that the wire doesn't come loose.
If you have extra space on the cylinder after coiling, cut it off so that you only have about 1 cm of free space in the end of the tube. We want the cylinder and moving coil to be as light as possible.
Step 12: Making the Moving Coil (Part Three)
Remember we left 1 cm of space on the tube in the last step?
Take a scissor and cut 1 cm slits all around the cylinder.
Then push the slits outwards.
Our Moving Coil is Done!
Step 13: Making the Diaphragm!
So now let's make the diaphragm.
First take the paper cup, and cut out a big piece of the paper from the cup. Mark a circle on the paper that is 2-3 cm bigger than the diameter of the tissue paper roll we cut earlier.
Cut out the circle.
Now mark another circle that's about 1 cm bigger than the diameter of the tissue paper roll, on the circle we just cut out.
Now cut out the circle from the cutout circle.
You will be left with a ring.
Step 14: Making the Diaphragm (Part Two)
Now take the ring we just cut out, and take piece of tape, and attach the tape to the ring. Make sure the tape covers the whole hole inside the ring. Cut out any excess tape hanging out of the edges.
Our Diaphragm is ready!
Step 15: Attach Diaphragm and the Moving Coil!
Alright, just as the step title says, we are going to attach the diaphragm to the moving coil.
Take the Moving Coil, and attach it's slits to the tape of the diaphragm.
Step 16: Making the Base!
Alright now let's make the base.
First take three craftsticks and glue them together.
Now glue down a wooden cube at one end of the crafsticks.
Now glue the other wooden cube on the same end of the craftstick, so the distance between the two cubes is 1/2 cm less than the length of the diaphragm.
Step 17: Making the Base! (Part Two)
Now place a bunch of Magnets right between the two wooden blocks we placed earlier. Glue down the magnets.
Step 18: Making the Base! (Part Three)
This step is optional.
Take another cube and drill a hole so that you can screw the cube onto a tripod. Then attach the cube to the craftsticks using glue.
Step 19: Putting It Together!
Now take the diaphragm, and glue it down on the two wooden blocks. Make sure the coil doesn't touch the magnet, and can move freely up and down around the magnet.
If you look carefully you will see the diaphragm for my microphone doesn't look like a circle anymore, I changed it to a rectangle, although it's not necessary.
Now take the 3.5 mm female Headphone jack and glue it down to the base.
Step 20: Finishing the Microphone!
Alright so now comes the most important part. You have to take the two wires coming from the coil, and remove their insulation.
Please do not skip this step. There are multiple ways to do it. You can use a sandpaper to scrape off the enamel insulation. You can use a scissor to carefully scrape off the insulation. You could also use fire to burn the insulation.
Now comes another difficult step. The step for connecting the wires.
If you remove the black rubber insulation from the jack, it will reveal 4 wires usually, sometimes three.
You have to connect the ground wire and Mic wire to the two wires coming from the coil.
It might be difficult to figure out which wires are ground and mic. One of the pictures show the wiring for 3.5 mm male headphone jack. However I couldn't find a picture online for the 3.5 mm female headphone jack wiring. So you will need to do some checking with the multimeter to figure that out.
Solder the wires to make it permanent. If you yet haven't figured out the wiring of the microphone, don't solder, just use alligator clips to connect the wires. You could test out the microphone, and if needed you can switch the wiring.
Step 21: Time to Test It!
We are finally done with the making. The pictures show what the microphone looks like.
Plug in the microphone to the computer or the phone using the jack. Open up an audio recording software, I used Audacity on my computer and my default sound recorder on my phone. Hit record, and speak loudly into the diaphragm of the mic. Tap the diaphragm for a more clear response. If it is working then great! You are done with the build!
If it is not working then look at the next step for trouble-shooting tips.
And the audio recorded by the microphone in a quite room is attached to the file. Keep in mind that I spoke really closely which is why the sound was pretty audible.
Step 22: Troubleshooting Tips
So in the next few paragraphs I will try to solve a few of the problems you might be facing while making it.
Problem 1: MY MIC DOESN'T WORK YOU LIAR! YOUR EXISTENCE IS JUST AS UNWANTED AS THIS INSTRUCTABLE.
Solution: I am sorry that your mic didn't work, but I can assure anyone that I didn't post a fake instructable. ( This happened to me countless times on youtube, people blaming me for their circuit not working.)
Problem 2: The Mic doesn't work, would you help me fix it?
Solution: This is a better way to express your opinions and needs. Alright the mic may not be working due to several reason. Did you properly remove the insulation from the ends of the coil? Because a lot of times people don't do it and magically their mic wouldn't work. Did you connect the wires properly? That's the biggest issue you can have. Change the wiring, maybe you didn't pick the ground and mic wire from the jack properly.
Problem 3: It's too frigging quiet!!
Solution: Use an app to amplify the audio (audacity). Or the problem might lie in the number of the coiling. You could try reducing the turns on the coil. Also you could try using stronger magnets. Lastly, try switching the wood cubes with springs or something flexible, it will allow for better movement of the diaphragm and louder noise.
Problem 4: My microphone doesn't pick up high pitched noise.
Solution: It's a problem with the type of microphone we made. High pitch noise have high frequency, or the waves cause the particles in the medium to oscillate extremely fast. However since moving coil microphones have really bulky diaphragm because of the coil being attached to it, the diaphragm can't move fast enough to capture high pitch noise.
Problem 5: The microphone picks up too much noise from background, and there's a lot of static!
Solution: It's a pretty rudimentary mic, it will always suffer from simple setbacks. It will pick up too much noise most of the time. However you can keep a foam or filter infront to block wind from hitting the diaphragm.
Problem 6: It still doesn't work.
Solution: Life is difficult, and it is okay to accept defeat sometimes.
Step 23: Final Words!
Alright, so I have been typing for a while, and I don't think I can keep it going for longer. So let's bring it to a close.
I hope you guys found this instructable kind of useful. I hope it was simple enough to understand. And I hope that I didn't misinform you anywhere. If I did make mistakes please let me know so I can fix them. Also a few images in this instructable are not taken by me, so credit goes to whoever owned them.
I am limited in my knowledge in electronics, so I apologize once again for any mistakes. Thanks for reading this poorly written instructable.
Participated in the
Explore Science Contest 2017