Motor Speaker

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Introduction: Motor Speaker

Here's a great demonstration of how a motor can be used as a speaker for less than 5 dollars. It took 5 minutes to put this whole thing together, without soldering a thing!

Step 1: Materials

Materials and tools used to make this:

(1) LM386 Chip from Amazon
(1) Breadboard from Amazon
(1) Slow motor, got mine from an old printer
(a couple) alligator clips and jumper wire
(1) Cheap earbuds
(1) Multimeter or continuity tester
(1) hobby knife
(1) wire cutter
(1) piece of fine sandpaper
(1) Something to play music

Step 2: The Schematic

Here's a schematic so that it's easier to follow along. If you don't know what a schematic is it's basically like a little map of electronics that tells how things are connected. The big rectangle thing is the chip, and the rest is pretty self explanitory.




numbering of pins on the 2nd picture

Step 3: Prepare the Earbuds

Cut of the ear bud part leaving you with the audio jack part

Step 4: Strip the Wires

Using a Hobby knife (careful, they are very sharp!) cut through the rubber insulation on either the left or right side (doesn't matter, we only need one)

Once you cut through the insulation, use some fine grit sandpaper to uninsulate the 2 fine wires.

Step 5: Lable the Wires

Using a continuity tester (testing if 2 things are connected) place one end on the jack (see picture) and the other on one of the wires. If they are connected then then we'll call it audio negative, if not connected we'll call it audio positive, and the other wire is audio negative

Step 6: Insert the Chip

Insert the LM386 into the center of the bread board, so that no pins are connected. You might have to push the pins in a little to make them square.

Step 7: Connecting the Audio

Since the audio wires are really thin, we need to use a jumper cable (any thick wire that fits in the bread board will do) and alligator clips. Insert a jumper wire into pin 2. Insert another one into pin 3. Attach an aligtor clip to each wire. atach the Pin 2 to audio + and Pin 3 to Audio -.

Step 8: Add the Motor

Attach a jumper wire to pin 5, along with an alligator clip to the motor. you can then attach the other end of the motor to the - of you battery. You can now also attach pin 4 to the - of the battery using the wire and alligator clip.

Step 9: Prepare for POWER

attach a wire and clip to pin 5. You are going to be connecting this to the+ of the battery.

Step 10: Hook Up Some Music and Listen to the Motor!

Plug in an MP3 player and attach the clip onto the + of the latern battery. If you got a slow motor you should be able to here the music if you put it on a solid surface such as a table.

Step 11: Care for a Listen?

You can also hear lyrics very well, but I wanted to put this up on metacafe, so I had to use free music or stuff like that.

http://www.metacafe.com/watch/797154/motor_speaker_take_2/


Step 12: How Does It Work?

Speakers work by pushing a cone up and down at different speeds (frequency) vibrating the air.
Here's a video to explain it: http://electronics.howstuffworks.com/speaker.htm
This motor speaker works by vibrating material around it by changing the speed (every so slightly) that the motor turns.

Have fun with your motor speaker!

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    43 Comments

    I can't tell the orientation of the Chip on the schematic. Could you help me with that?

    ll you neesis stero no mplfier

    can i use instead the motor a relay? to make lights go with music

    so is the chip a good amplifier? b/c i want to build a bunch of cheap speakers to sell at school

    2 replies

    yea but u wanna put a large cap(1000uf or greater) on the output.. i made one and hooked it up to a 4x1" oval speaker w/o the cap and it was all fuzz.. then i put in the cap and it sounded great pretty good.. ive experimented with different speaker sizes, up to around 5 or 6" round, and all have worked good.

    i know your post is old but a mega thanks for posting this. my friend has been hassling me ever since hesaw my speakers i had and now he wants some and i dont want to make the extra trip to buy some more. now that you have told me this i can make my own so he can leave me alone.

    um lets say pin 5 ran away dont as is there any alternatives plz help thx

    I did this a while back (using a pair of transistors instead of an LM386), using a small fan motor. The idea was, the fan motor would play music with its internal coils while spinning, keeping me cool. Turned out the motor would turn/respond to only the lowest of frequencies, even then, it hardly worked. Sigh...

    HI! Me again. :) Earlier I asked you about the headphones. So I just make this schematic and instead of the motor I put an LED? Cool! Shouldn't be too hard. Do I really need the 6V battery??? When I make this I just hook it up to the headphone speaker an it should work, right?

    2 replies

    you need some sort of voltage supply, such as 5 volts, or 6 volts. I just chose 6 volts cause I had that lantern battery lying around. It won't work without the extra power good luck :)

    I would use the power supplied from a USB cable(I'm all out of batteries, and don't feel like killing myself with 120V), since it generates about 5.25 to 5.75 V of voltage and about 100 to 500-600mA of current. And like you said, I just had the severed USB cable lying around.

    all you have to do is put headphone wires onto a motor and plug it into an ipod

    4 replies

    If you connect it directly to the motor the music player, the large inductance of the motor will damage it. Like connecting a transistor directly to a relay, the voltage spike will damage the transistor. Normally you would add a diode, but sound is AC so it wont work.

    i tried similar stuff with way bigger inductoprs (about 1.5 HY) and did not damage the player you may add 2 very fast diodes in parallel to the motor in both directions. i think itll be relatively good protection. unless the voltage is above 0.7 V i dont think theyll affect the sound much. for higher allowed voltage connect some diodes in series

    It's just like connecting a relay to a transistor. You have to add a protection diode to block reverse-EMF signals from damaging the transistors. Unless the player has it own protection, it will damage it.

    i guess you are right here. i just say that i did something more severe and did not blow up my player since diodes open only at 0.7 V maybe you can use them in both directions for protection. and maybe connect in series to get freedom up to 1.4 or 2.1 V etc

    user

    The guy below me Kenny94 is absolutely right, all you have to do is chuck the headphone wires to the motor ones. The chip doesn't really do anything. Ive done this before and the only reason why the motor sounds so loud is because it is on top of the metal which echoes it through that and through the table. If he took it off you would hardly be able to hear it.

    1 reply

    If you connect it directly to the motor the music player, the large inductance of the motor will damage it. Like connecting a transistor directly to a relay, the voltage spike will damage the transistor. Normally you would add a diode, but sound is AC so it wont work.

    from my experiences adding extra power to the audio in of any device is a bad idea. fried my last mp3 this way

    Can you hoock up a speaker to it?