Proximity induction circuit and circular magnetic accelerator

Presumably you are pulsing magnets; you have to both turn them ON when the ball is approaching and OFF when the ball is about to depart. The problem is solved in some particle accelerators, by modeling the acceleration of the particle and setting accurate time delays to the multiple acceleration stages. Since the acceleration is intended to be one unit per stage, your times will be in reciprocal of the order of a quadratic series (1/M**2 for M = N, N+1, ...N+P).

The full capacity of your accelerator is reached when the ON/OFF cycle is too slow for the fast-moving ball.

If you're pulsing magnets in the vicinity, DON'T use an induction sensor. The pickup-noise problem is... severe.

The circuits similar to what you are looking for are used for the magnetizing of permanent magnets and/or surge testing of equipment. Typically, they use powerful thyristors or IGBTs. Those devices are quite expensive.

The relay contacts will be welded together by the surge current, unless this is a special relay designed for this kind of operation.

Vladimir Vassilevsky

DSP and Mixed Signal Design Consultant

Search for "coil gun" on the Internet. The idea is to put a piece of steel in a plastic tube energize a series of magnets to propel the steel out the end and into a target.

Depending on how many joules you need to switch it can be inexpensively done with SCR's (thyristors) or IGBT's if they cycle time needs to be very short (small loop).

News==----

Hide quoted text -

Thanks for the suggestions. I will be exploring optical sensing methods, as any induction sensors would be swamped, as was basicly pointed out.

On Jul 3, 8:32 pm, jhead wrote: [....]

You also need to look at how you do your switching. Ideally, the coil current will be snapped on just before the ball gets to the coil and off just as it passes the middle of it. A sharp turn off, will actually repel the ball out of the coil.

Ideally, the energy from the coil ends up back in the storage capacitors. This will save on the heating of the system.

For anyone interested, here is my 3d rendering of my pre-prototype idea:

For a steel ball, there will be two completely different effects taking place that can exert force on the ball. At low frequencies, where the magnetic field has time to wait for the surface eddy currents to die down, so the magnetic field can pass through the ball, there will be forces caused by the permeability of the steel. Those forces always act in the direction that will increase the total magnetic flux. The other and higher speed effect is the reaction between the applied magnetic field and the magnetic field created by the induced current, circulating in the surface of the conductive ball (eddy currents). Since eddy currents inhibit changes in the flux already passing through the ball, this force can act as an attraction or a repulsion, depending on the polarity of the external field, compared to the one produced by the eddy currents. This effect is a lot more complicated to describe in a few words, but, for high speed rail machines, is the dominant effect available to produce force, unless the moving body is relative non conductive.