OK! That picture was much clearer than what I saw. Driving a steel ball along would require a short pulse as it got close, and then switch off the electromagnet to avoid adding any drag.
It would be a sort of electronically commutated synchronous motor sort of scheme. Fun but not very practical. Consider how accurately positioned those two wires that serve as rails for the ball to roll on need to be positioned.
Besides all that, a "7/16 inch steel ball" is quite a small object to be watching from any distance. Certainly technical-types would stop and watch, but I don't imagine that it would attract big crowds.

 

I kind of want to build one too. Im very curious to see what TS ends up using. The use of IR sensors make it easy to adjust timing, but the wire and isolated track is very low tech and reliable. My brain is thinking of multiple colored balls just winging around for entertainment.
Like a low quality train set. Get all the noise without having to learn gauges or how to paint miniatures.

 

The TS, 12VOptimusPrime, has not replied to this thread since Feb 17th, 2026. and has not been on AAC since Feb 25th. Either the TS is building something or has lost interest.

 

My brain is thinking of multiple colored balls just winging around for entertainment.

I got the impression the TS wanted the ball to travel around the perimeter of the room and not "winging" around like in the video. I grabbed the video because it's something I've seen before. Having the ball circle the room like an HO or O scale train chugging around is the intended idea. But by now I think we've probably scared him away from this idea. Or perhaps he's building it right now. But he hasn't been seen in over six months.

An electromagnet works much better on a steel ball than on a glass marble.

"Marbles" versus "Steel balls": I remember playing marbles in school. We had boulders, purees, cat's eyes, bumble bees, and yes, we even had "Steelies". The use of the term "Marbles" in place of steel balls seems like a benign point. We know what's meant.

 

Just to throw this out there - you could use a motor spinning a rubber wheel. Every time the marble reaches the wheel it gets flung along the track just like the old accelerator stations used in MatchBox Hot Wheels (edited) cars. However, I think at this point I'm done following this thread.

 

Actually, the whole drive scheme can be implemented with no electronics at all. Consider making the track one side of the power feed. Then the other side of the power goes to one end of each coil, and the opposite end of the coil connects to a copper contact strip that the steel ball contacts just a bit before it enters the coil, and that completes the circuit to energize the electromagnet. It would be a lot like an electric buzzer, with the contact timed to pull the ball along and then switch off at the last moment.