I saw this project that takes metal marbles and accelerates them through a magnetic coil online and wanted to ask a few questions before I start working on the project. The goal is the create a track around the game room where the ball travels around the sides of the walls and hits these electromagnet stations where the ball is given a boost of velocity to make it to the next check point and continue traveling around the room. Maybe later I can incorporate lights at the checkpoints and such but for now I want to keep it simple.

The project I am referring to can be found here: https://www.instructables.com/Electromagnetic-Marble-Accelerator-for-Gravitrax/

The principle: ball travels past a mark, a signal is sent to a controller which is then relayed to turn on a coil which powers the marble just long enough to get to the center of the coil and then shut off the magnetic field. This prevents the magnetic field from pulling back on the marble after the midway point.

My question is, can this circuit be created with an IR beam to detect the ball, sub-second 12V adjustable timer relay (similar to an NE555), MOSFET rated for the coil current, flyback diode, and the coil itself? I dont mind programming the ESP32 or Arduino, but for others who might want to make one I was thinking the adjustable timer relay might be easier. What are your thoughts on the hardware to build something like this? Or do you have other ideas on how to make this circuit more simple using a pre designed board/module.

 

So you basically want to recreate that circuit without the Arduino? I believe that is definitely doable. At worst you lose a hair of efficiency but it seems to me that a micro-processor is overkill for this.

This forum has a rule against discussing rail-guns and I'm asking a moderator to take a look at this. I think you're OK but we should get their thumbs up before digging in.

 

So you basically want to recreate that circuit without the Arduino? I believe that is definitely doable. At worst you lose a hair of efficiency but it seems to me that a micro-processor is overkill for this.

This forum has a rule against discussing rail-guns and I'm asking a moderator to take a look at this. I think you're OK but we should get their thumbs up before digging in.

I can definitely understand because I have seen some where they use large voltage and it sounds very dangerous. This one is a small project for the game room and I only plan to use 12V to power the a 100g coil. Thank you for asking for me!

 

I would suggest using the hall sensors as mentioned in the link.
What is the diameter of the steel ball?

 

I would suggest using the hall sensors as mentioned in the link.
What is the diameter of the steel ball?

Okay I bought some of those hall sensors and some magnets. The ball bearings I got are from amazon they are 7/16 inch.

https://www.amazon.com/Diameter-Har...b494068fce2c494379&qid=1771387550&sr=8-2&th=1

 

Meaning the SS49E sensor ?

 

Consider using optical means to detect the balls- this "cross-domain" sensing scheme avoids annoying interactions between the sensing and driving magnetic fields.

 

Meaning the SS49E sensor ?

Yes the SS49E is the one I ordered. I also ordered a 5V infrared sensor not knowing which route I was going to go.

 

Many moons ago (ok, decades), I made something like this, except it accelerated something more cylindrical than spherical. The "track" was a piece of narrow hard plastic tubing, with a series of coils made from basic solid core wire. All had one end commonly wired, the other end of each coil went to a series of thumbtacks in a line, and was all powered by a small 12 volt AGM.

Placing the cylindrical metal object at one end, simply "striking/rubbing" the bare wire from the common side (with the battery in between in series) along the series of thumbtacks, I could accelerate the object fast enough for it to strike a soda can placed a few feet away (no damage was done to the can).

I had always intended to revisit the project, but never did. I figured that all I needed to do to make it "automatic":

1. Between each coil, and immediately prior to the first, put an IR LED and photo-transistor pair across the tube. You might also be able to use a photo-reflector pair.
2. Wire the photo-transistor to another transistor or mosfet that would trigger the coil.
3. The object would pass thru, and the blocking of the photo-transistor would trigger the coil directly in front of the object.

This would attract the object into the coil, and by the time it passed, the coil would be turned off, so that the object could pass unimpeded. That's all that should've been needed. No microcontroller, no delay relays or anything like that.

Additional things to make it better (more efficient) would be to wind much better coils (I figured using pre-wound solenoid coils would work best), and also adding large capacity "buffer" caps for voltage dumping (back then, I was thinking large electrolytics; today, I might opt for super-capacitors).

 

Additional things to make it better (more efficient) would be to wind much better coils (I figured using pre-wound solenoid coils would work best), and also adding large capacity "buffer" caps for voltage dumping (back then, I was thinking large electrolytics; today, I might opt for super-capacitors).

See https://forum.allaboutcircuits.com/...-gauge-for-pulses-current.189436/post-1768216

 

Consider that a 7/16 steel ball rolling around a game room big enough for one person to stand up in will not be very impressive, nor even very easy to see, I suggest thinking the whole project over very carefully.
AND consider that the 7/16 ball is similar in size to a .38 caliber slug, it may have the potential to be unsafe.