Groovy Sounds
Pencil, pin, paper = phonograph.
Make a real record player out of simple materials.

Making the turntable

Slide the pencil into the hole of the LP, and wrap some tape around it above the point. The tape should be just thick enough to stop the pencil from passing back through the LP. Make sure the pencil is perpendicular to LP, then tape the pencil to the LP so that they will spin together.

Making the arm and sound cone

Form the piece of paper into a cone and tape it. Then, insert the pin through the tip as shown in the photo.

1. Hold your pencil and record on a tabletop like a top. The pencil point should rest on the table and the eraser end should be pointing straight up.

2. Gently twirl your pencil, making sure your LP stays as parallel to the tabletop as possible. Turn the LP clockwise. Try to turn the LP at 331/3 rpm (good luck!).

3. Your partner should position the paper cone so that the pin is in a groove of the LP, then gently hold the open end of the cone.

4. Allow the cone to move with the motion of the record while the pin stays in the groove.

5. Listen to what comes out of the open end of the cone.

Music! Did you hear it?

The groove in the LP isn't smooth. It has microscopic bumps and bends in it that correspond to the music that is recorded on it. As the pin spirals around and around in the groove, it hits these bumps. These bumps cause the pin and therefore the paper cone to vibrate up and down and side to side. The vibrations in the cone cause the air to vibrate. These vibrations radiate out from the cone to your ear - and you hear whatever has been recorded on the LP.

Grooves in a 78 r.p.m phonograph record


What could you do to make the music louder? What could you do to keep the record turning at a constant speed?