Speakers From Scratch

Homemade Speakers

A Project By:
Rohan Tiwari 2014157
Anant Mittal 2014015
Get Surprisingly Good Quality Music From Disposable picnicware

I tried to build homemade speakers using various materials for the cone. This design is the best. Paper plates are too soft, and disposable plastic cups vibrate too much, but stiff, lightweight Styrofoam produces sound quality that competes with commercial speakers. I really mean it — you will be surprised!. The quality of the speakers depends on the extent of smooth movement of the magnet and Styrofoam forms a very good diaphragm and is also easily available.

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The Idea:

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To understand how a speaker works, I took one apart.

In it's simplest form, a speaker is just a coil of wire glued to a piece of paper, and placed near a permanent magnet. When alternating current flows through the coiled wire, it is either attracted, or repelled by the permanent magnet.

The audio signal from your stereo is a form of alternating current. When attached to a coil of wire and set near a stable magnetic field, the variations in polarity and amplitude will make it vibrate thousands upon thousands of times per second.

If this coiled wire is attached to a diaphragm, the vibrations will push a larger volume of air and generate sound waves that we can hear.


Material Required:

  • Neodymium magnets( Small and cylindrical) (1) You can use just 1 if it's tall enough, but I used 3 thin ones stacked together.
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  • Wood, flat piece (1) or cardboard; should be larger than the plate. I used cardboard, but wood damps vibrations better.
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  • Audio plug (1)
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  • Glue (1) Hot glue works great.
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  • Tape (1)
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  • Bond paper (1 sheet)
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  • Business cards (2)
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  • Copper wire, 35-gauge, enameled (1)
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  • Styrofoam plate (1)
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  • Soldering Iron
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Our Experience:

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The Video shows our experience of how we made the speakers using household materials.
The Link isOur Experience


Steps to Success:

Step 1 : Make Cylinder

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Stack about 5-6 button magnets to form a 1-2" cylinder.

Cut a strip of paper and roll it around the stack of magnets, then tape it to itself.

Then, cut a second strip of paper and roll it over the first, then tape it to itself.

Note: The two pieces of paper should not be connected to each other. Instead, they should be able to slide apart freely. The inner paper is going to serve as a spacer, because when it's removed, it will create a slight gap between the top tube and the magnets.

Step 2: Form the Voice Coil

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Wrap about 50 turns of wire around the tube. It doesn't have to be super tight, but should be firm.

Then secure the wire coil in place with some hot glue. Pull the stack of magnets and inner coil of paper out of the tube, and you should now have a hollow tube with a winding of wire around it. This is your "voice coil".

Cut the voice coil to a length that will slide over the magnet stack.

Glue the voice coil to the bottom side of a paper plate.

Step 3: Cut Your Speaker Out

While you're waiting for the glue to dry, start cutting out the shape of your speaker in the bowl.

Step 4: Attach the Voice Coil

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Then glue the magnets in place. When the top portion is dried, hover the wire coil near the top of the magnets.

Fit the paper plate with the voice coil over top the magnets, and glue the plate in place.

Step 5: Paint

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I chose to paint the speaker black in an attempt to make it look a little better.

Step 6: Remove Wire Coating

Remove the coating from the tips of the wires. You can use sandpaper or an open flame to burn off the enamel.

Step 7: Hook Up and Play!

Hook your speaker up to a stereo with a built in amplifier and press play.

You should hear your music playing out of your paper plate!

Step 8: Troubleshooting

If you don't hear anything, double check your connections. The two wires from the voice coil should connect to the positive and negative terminals of one channel of your system. It doesn't really matter which wire goes where as both will work.

Your stereo will also need to have a built-in audio amplifier to push a higher wattage to the plate. If you're trying to run this from your iPhone or MP3 player, you might hear a faint noise, but your results will be much better if you first amplify the power output.

If you still don't hear anything, either your wire is damaged (shorting out or broken), you don't have a good connection with your wires to your audio source, or your magnets aren't strong enough.


Science Behind It's Working:

Various types of transduser are used to convert electrical signals to sound in speakers.However ,the speakers we have opened up ,seemed to work on the moving coil.

The moving coil driver is the most common type used in speakers. The principle consists of a stationary magnet element affixed to the frame of the headphone which sets up a magnetic field.The diaphragm, typically fabricated from lightweight, high stiffness to mass ratio cellulose, polymer, carbon material, or the like, is attached to a coil of wire (voice coil) which is immersed in the magnetic field of the stationary magnet. The diaphragm is actuated by the attached voice coil when the varying current of an audio signal is passed through the coil. The alternating magnetic field produced by the current through the coil reacts against the static magnetic field in turn, causing the coil and attached diaphragm to move the air, thus producing sound.The current in the coil is produced as a result of basic principle of physics called electromagnetic induction(EMI) which was given by Faraday.

Inside a Speaker:

1. Diaphragm
2. Electromagnet (coil)
3. Permanent magnet

The frequency of the vibrations governs the pitch of the sound produced, and their amplitude affects the volume – turn your volume up high enough and you might even be able to see the diaphragm covering the cone move.
To reproduce all the different frequencies of sound in a piece of music faithfully, top quality pieces typically use different sized cones dedicated to high, medium and low frequencies.
A microphone uses the same mechanism as a speaker in reverse to convert sound into an electrical signal. In fact, you can even use a pair of speakers as a microphone!

Sinusoidal Am stimulus is special because its envelope consists of a single sinusoidal component. range of modulations are present which can be summarized by the modulation spectrum. the subjectively experienced quality of a modulated signal depends on the modulation frequency so that the modulation spectrum also defines different perceptual ranges.


Conclusion:

The experiment shows that a speaker is based on the simple movement of the diaphragm and is based on the scientific principle of ELECTROMAGNETIC INDUCTION.
The quality of the sound and movement of the diaphragm can made by using a strong magnet and good quality material for the diaphragm.

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