This design of oscillator is taken more or less from the BobThomas drawing. It consists of two triangular plates, a topplate and a bottom plate. The bottom plate has a cup in eachof its three corners facing up. In each cup sits a pool ball.The top plate also has a cup in each of its corners but theseare on the underside of the plate and face down. Each cup ofthe top plate sits on one of the bottom plate's pool balls.This arrangement allows the top plate to move freely over the bottom plate, as long as the pool balls remain in the cups.Note that cups are bowl shaped causing up and down movementof the top plate as it moves horizontally.
The top plate has a piece of aluminum on its top surface, this aluminum having a notch in it. The bottom cone sits in this notch.This allows the bottom tip of the cone to move horizontally and vertically.
One more detail is that in the center of each plate is amagnet. The magnet for the bottom plate sits on top of theplate. The magnet for the top plates hangs under the plate.These magnets are oriented so that they attract each other but are spaced out due to the height of the pool balls such thatthey do not touch. These magnets pull the cone tip back to the center.
Looking down at the surfaces of the plates that face each other.On the left is the bottom plate with the pool balls sitting in its three cups. In the center is the magnet. On the right is the top plate. Note that it is upside down as the three cups are normally sitting on the bottom plate's pool balls.
On the left is the bottom plate, turned upsidedown so as to show its under surface. On the right is the top surfaceof the top plate. The dark mess in its center is a bunch of ductthat holds the piece of wood that holds the aluminum that has thenotch in it. The three pool balls are sitting on the table in between the two plates.
Almost side view of the bottom plate withthe pool balls sitting in the three cups. The magnet is visiblein the center. The cups were made of Christmas tree balls that normally hang on Christmas trees. These were bought in a craft store. They come as two plastic half spheres which people can join together after filling them with various decorative things.I simply used a hack saw to cut them to the needed size.
Close-up of a pool ball sitting in its cup.Note that it is not a snug fit, allowing the pool ball tomove around in the cup.
The cup without the pool ball so that you can seethat it is bowl shaped.
Side view showing the top plate sitting onthe pool balls which are in turn sitting on the bottom plate.A gap can just be made out between the two magnets.
Top/Side view showing the two plates as theywould appear when sitting at the bottom of the drum.
Currently I have 4.5 inch magnets attached to the oscillator andthe gap between them is very small. The strength of these magnetsare such that they hold the oscillator too rigidly centered. I'll experiment with different sized magnets as well as with largegap sizes but only after I've solved some of the other problems mentioned on my main 45 gallon drum experiment page.
