Homemade Gramophone (Phonograph)

I'm ending the year listening old music from Vinyl disks, So I build my home-made gramophone using a pin and a plastic cup. With my lego set of "mindstorms" I was able to spin the disk at 33 RPM (approximately). Here are some photos an a video of my gramophone. (12/31/2006)


Many times I can see old vinyl disks on the flea market. Many disks have good music and the sound is not quite "hi-quality", but the sound brings back good memories.


If you are old and cranky like I am, you will know what I'm talking about. If you think that big black vinyl disk is a freesbie, you are totally lost.


Long time ago, Thomas Alba Edison invented the Phonograph to make some money and continue with other inventions, he used cilinders but later, somebody used disks and called the invention "Gramophone". Disk have more advanteges than cilinders. The way it works is simple: A needle picks the sound from the grooves and amplifies the sound. So to make my own gramophone I need a pin, a plastic cup (paper cup should work better) and a mechanism that rotates 33 RPM.


The difficult part of the gramophone, is the mechanism to get 33 1/3 revolutions per minute. The main parts of the "phonograph", is just the pin and the plastic cup.


Just put the pin inside of the cup and you have ready the amplifier and the speaker.


Using my "Lego Mindstorms" I was able to build a mechanism that rotates the disk approximately at 33 RPM.


Here is my Phonograph playing can-can music. (Offenbach - Gaite Parisienne)


Another view of my Phonograph. This is a low-tech sound system, but works fine, I was able to hear Can-Can for all day long. ***WARNING: It destroys disks. DO NOT BUILD IT. This page is as educational purposes only***


Here are some photos showing the mechanism details:



It have four rollers to avoid too much oscillation of the disk. Those rollers do not touch the disk unless there is too much vibration or oscillation. It doesn't use special programs, it just uses the RCX to provide power for the motor.


Here are the previous version that didn't worked very well:



I'm not sure why I made the first version with the arm crossing the diameter straight instead of diagonal. It was working but not very well. I think I was using the idea of a CD player.


Here is a video showing how it works and the quality of the sound:



I had to put two napkins inside the cup to reduce the high frecuencies. The plastic cup amplifies high frecuencies very well, so the sound was not quite good. After I put the napkin inside, the sound was better. Using paper cups instead plastic cups, will improve the sound.


... by the way,





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