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chalker wrote:Regarding stopping the vehicles at the end of the run, a simple solution the national supervisor came up with is to just put a metal plate on the table at the end of the track. The vehicles fall off the track and their magnets immediately lock them onto the plate so they won't move any further.

Another obvious and great idea will probably incorporate it into our track this year.

So I'm thinking of making an RS latch switch with a simple relay so I can turn on and off our motors easily. I'm pretty sure relays don't count as ICs, but I'm worried they could cause problems at competition because they sorta looks like ICs. Has anyone else tried something similar? I've been also looking for a simpler stay on, stay off microswitch as opposed to the momentary ones but couldn't really find one that was ideal for our vehicle.

Yeah, that's what I have, it's a relay that's wierd up to act as a latching relay and I've had a no trouble with it at all. It'll be pretty obvious that it isn't an IC when you hear the click sound of the contacts also, make sure you get a relay large enough to handle the current, the one I have is rated at 5A, but that's AC, it's only 3A DC, so I had to use multiple poles to handle all the current.

chalker wrote:Regarding stopping the vehicles at the end of the run, a simple solution the national supervisor came up with is to just put a metal plate on the table at the end of the track. The vehicles fall off the track and their magnets immediately lock them onto the plate so they won't move any further.

Personally, I would be afraid that this solution would tear the magnets off the current design of my vehicle, as they are typically pushed up into the vehicle, not down away from it.

Granted, any national competitor now has access to information on that and can thus test a similar solution on their vehicle to ensure it will not cause the problem described.

Schrodingerscat wrote:

chalker wrote:Regarding stopping the vehicles at the end of the run, a simple solution the national supervisor came up with is to just put a metal plate on the table at the end of the track. The vehicles fall off the track and their magnets immediately lock them onto the plate so they won't move any further.

Personally, I would be afraid that this solution would tear the magnets off the current design of my vehicle, as they are typically pushed up into the vehicle, not down away from it.

Granted, any national competitor now has access to information on that and can thus test a similar solution on their vehicle to ensure it will not cause the problem described.

It's interesting your design might have that problem. Another similar process I've heard of from a couple supervisors is to have a metal plate at impound. Teams are asked to put their vehicle on the plate then remove it. If they have difficulty taking it off, they likely have rare-earth magnets, which are prohibited. You should be prepared to do that as well.

I must say that that doesn't seem like a very good test. I have seen ceramic magnets claiming 20 lbs of pull, small enough that six could probably be placed on a vehicle - which would then be quite difficult to remove from a plate. The 5 lb variety is pretty widely available, and even six of those that would not be easy.

Flavorflav wrote:I must say that that doesn't seem like a very good test. I have seen ceramic magnets claiming 20 lbs of pull, small enough that six could probably be placed on a vehicle - which would then be quite difficult to remove from a plate. The 5 lb variety is pretty widely available, and even six of those that would not be easy.

I agree with this entirely. It isn't hard to find ceramic magnets with 6-9 pounds of holding force, 8-10 of which could be placed on a single vehicle. It would basically be like trying to lift a 60 pound weight.

If my vehicle were placed on a steel plate it would be near impossible to pull it straight up off the plate, but chances are you could roll it off just fine.

Holy cow, 9-20 lbs of pull! What kind of magnets are you using?? I can guarantee that the ceramic magnets we are using (the ones from Kelvin) have nowhere near that amount of pull. I would imagine a car with 10 or so such magnets could support upwards of five pounds although I really have no idea as to what 10lbs of pull off of a steel object translates to in terms of "push" when two such magnets of the same polarity are placed near each other. Our car weighs 3.5 pounds and levitates just fine but I can pull it very easily straight up off of a steel plate.

joeyjoejoe wrote: Our car weighs 3.5 pounds and levitates just fine

Dang. Are you still getting reasonable times with a weight that high? Also, no idea how steel pull relates to the repulsive force of the magnets.