Most of the days I wake up to M.S Subbalakshmi’s ‘suprabhatam stotram’, ride my bicycle to ‘Fly me to the moon’ and love to hear the piano while sleeping.
I’m not a music addict but yes, some particular tunes are a part of my routine.
Point being, like everyone else, headphones are now an indispensable accessory to me too.
Last week, while exploring some experiment ideas for our science section, my colleague Sandeep made a great paper speaker. But it somehow didn’t give a very nice sound output. We made some changes in the materials used, and it gave birth to a fantastic balloon speaker
What is sound? Vibrations, right? (Actually pressure waves, but let’s not get into that)
If you are hearing a sound, it means something is vibrating somewhere.
The frequency of the vibration decides the tone of the sound and the amplitude decides the volume of the sound.
The string of the guitar vibrates faster than the diaphragm of a drum. Hence, the tone is different.
So this is what we did, we wanted to make a speaker. Simply put, we wanted to create vibrations of the frequency of the electrical signal that we get from the iPod speaker jack.
Let me take you through the making:
This is what you need:
1> Big Baloon
2> Something to stretch the balloon on. (I used a section of a PVC Pipe)
3> A magnet: this has to be a small and strong magnet. A cylindrical neodymium magnet is the best choice. There are not many vendors around. So you may try to hack some from magnetic key-chains. Or just use a strong ferrite magnet
4> 35 gauge laminated copper wire.
5> Foamboard/ cardboard
Step 1:
Cut the balloon and stretch it over the PVC pipe
Step 2:
Find a thin tub that can ‘just’ cover the magnet. I Cut a 5ml Syringe for this. The size happened to be perfect to ‘just’ cover the magnet. Now make a solenoid out of the tube by winding the 35 gauge wire around it. I don’t remember how many turns i did. But i stopped when it looked like this:
Step 3: Fit this coil at the center of the balloon diaphragm
Step 4: Cut a foam board piece of about the same size (not really necessary but looks good!) Keep the magnet at the center of the board. Drill 2 holes in the PVC pipe to get the terminals of the solenoid out
Step 5: Now keep the diaphragm on top of this such that the solenoid comes around the magnet. Connect a salvaged Audio Jack to these terminals
The Whole assembly looks like this:
Okay, so this is what is going to happen:
When i connect the Audio Jack to my iPod and play music, electrical signals will be transmitted and they will pass through the solenoid coil. This solenoid, thus, will become an electromagnet when the signal strength is high.
In other words, the solenoid is activated at the same frequency of the audio signal.
When the solenoid is activated, it will be attracted towards the magnet and so, the balloon diaphragm will be stretched downwards. When the solenoid is deactivated, the diaphragm will come back up.
All this happens at the frequency of the sound signal. Which means, that the balloon is vibrating with the frequency of the signal. What does that mean?
Check the Video:
And this one
Deepak, Sandeep and Arnav, we made it!
Extra Info:
http://electronics.howstuffworks.com/speaker5.htm
