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How can you make a cactus needle speak?-Keith
This is from some designs I found on the internet on how to make a phonograph. This is the first one using a tuna can.
In this phonograph the stylus slides sideways in straight tracks.
This is the gear box I made to turn the record. The big gear will hold up the album on the spindle.
I decided to put a binder over the shaft and gear for friction.
Snipping a hole for the shaft.
These just didn't work at all. It made the record wobble and didn't really hold it as the spindle turned.
I replaced it with this big wheel. It works great.
The gear box uses a worm gear to help the motor turn the record slow enough to sound like the right speed.
The whole record would swing around when it started and stopped. There was space by the gear end that caused the slop.
I cut some washers from a coffee can lid.
I used two to fill in the space.
Here is a simple example of a horn and pin player. Its a terrific activity template I used to begin. I didn't make this player though. It does seem like it would be nice for another workshop. What I needed to figure out was the horn/stylus thing: how to make them, how to get them to work.
It included a template for the horn to cut out of paper. Once we made one it seemed pretty obvious we just needed to roll paper into a cone shape, we didn't seem to need the template. One important thing to notice is the angle of the pin. I tried it straight up and own and it scrapes and skips.
When we first tried it Morgan plucked the cactus needle from Josh's plant. The needle was very thin, like a thick hair. We got the record motor going 'thisway' in the program ( clockwise) and set it to 10 seconds - too short- and then to 60 seconds. I just held it on the record and let it drag.
Once we tried the gearing for a while it just didn't seem to work well. It would start and stop with a shudder, and sometimes, because we were using the grey geared motors it would kill the program on the cricket. I believe the reason for this was that the motor actually generates voltage and the cricket has a circuit that protects it from any surge of current back into the cricket.
So Morgan and I talked and he suggested the pully as that was just like a belt drive on a real turntable. It absorbed the start and stops well.
I'm using a pencil to hold the horn and to allow it to turn with the record playing.
This is the cactus at my house. These are NOT like a hair. They are sharp, and stiff and hurt!
I picked this one off with scissors.
I put a dab of hot glue on it to hold it in place.
Click to watch and listen Listen. This is using the new cactus stylus.
The change here is the diameter of the pully on the spindle ( the axle going through the record) . It was twice as big as the earlier one. This was great because it cut the speed in half, and now I could have the 'setpower' up to 3-4. ( I had it down to 2 with the old pully and that was too week to really turn it off and on easily)
I made a contraption to hold the horn the right angle on the record.
The pink foam worked great because I could whittle it away until I had the angle right. The other thing to notice is that the horn can swing inward with the stylus' movement on the recording.
Click to watch and listen Here it is starting up and playing. Can you figure out what the recording is here?
What else
Learn to make copper sensors.
Read what Margaret wrote about her interactive storytelling idea.
Will food conduct electricity? Read about an activity that combines food and Crickets.

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