MagLev C [Trial]

[JTMess]

What is everyone using for batteries? A 9-volt is the typical choice, although it doesn't provide as much current as another 9-volt power supply could.

[baker]

A couple of questions for those that have alrady competed... We're making the platform for the mag lev vehicle just under 2 9/16 inch wide, almost 2 1/2 inch, anybody find themselves with a vehicle too wide to fit tracks, are most tracks the same width? Also I know there's a 50/50 chance that we will put the magnets on the vehicle in the correct 'north seeking pole' on the right or left side, but does anyone have or seen how they setup the track in general for competition? What side, in the direction of travel, do most set their 'north seeking pole'.

[OldSpice]

A couple of questions for those that have alrady competed... We're making the platform for the mag lev vehicle just under 2 9/16 inch wide, almost 2 1/2 inch, anybody find themselves with a vehicle too wide to fit tracks, are most tracks the same width? Also I know there's a 50/50 chance that we will put the magnets on the vehicle in the correct 'north seeking pole' on the right or left side, but does anyone have or seen how they setup the track in general for competition? What side, in the direction of travel, do most set their 'north seeking pole'.

I did the event last year when it was first introduced and I'm not sure if they've changed this, but the direction of travel in relation to the magnet's polarity unfortunately isn't standardized. I'm not sure if it's against the rules or not, but you could try and email the event director prior to competition and ask, but I doubt that'll work.

As for the track widths, you never know what'll happen. The first invitational I went to last year only 3 teams made it down the track due to the cars getting stuck.

[chalker]

As for the track widths, you never know what'll happen. The first invitational I went to last year only 3 teams made it down the track due to the cars getting stuck.

Which is why the current rules call for the vehicles to have shims or something to allow for you to adjust the width.

[twototwenty]

Since you don't know which way the car is going to need to travel, you really do need to make the car travel in both directions, instead of picking one and hoping the right track for your car will be used.

To do this, there are several methods. Two that are pretty good are using detatchable magnets, or (more easily done) is simply reverse the polarity of the power supply to the motor(s). the latter can be done by splicing together two batter snaps (if you are using a 9v battery) so that the polatiry i reversed.

I hope this helps.

[chalker7]

As for the track widths, you never know what'll happen. The first invitational I went to last year only 3 teams made it down the track due to the cars getting stuck.

Which is why the current rules call for the vehicles to have shims or something to allow for you to adjust the width.

And which is why I'm still confused (and being admittedly difficult) about rule 3.j. Shims will intentionally touch the sides of the track....

[JTMess]

I'm just looking for another opinion on whether or not capacitors are allowed. We are currently using some fans that came with capacitors preinstalled in them. We are using them along with a regular battery, so the capacitors aren't powering the circuit. I submitted a clarification on this exactly 3 weeks ago and unfortunately haven't heard back. Thanks for any advice!

[baker]

Yea, we have a small fortune invested in motors that are unable to do the job. We too have a motor ($10.00) from a company named LOSI that works pretty good but it has capacitors across the +/- connections of the motor. There is very little data about the specs of the motor let alone why caps are on the motor. Best I could guess is it helps during the starting phase of the motor, like a 120 v single phase AC motor. Not many hobby stores in our area carry the props we want too. Those companies listed on the resource page really aren't much help either. One company wants a min $30 order for stuff with very little information about what you are buying. We keep buying props at about $3 a pop only to find they don't have the horse power needed. If it wasn't for Walt's Hobby in Syracuse we wouldn't be able to have a working model. Like I said we have about $25-$30 invested so far and at least $15 of that is stuff that will not do the job, but because you have to drill out the hub, or solder on wires or what ever reason you can't return the items. And then you have to "shim" the vehicle so it may or may not work on a track... very little precision here..

[fleet130]

I have not researched the rules to determine if the capacitors are prohibited. If I were judging the event, I would ignore their presence, barring specific language in the rules prohibiting them. Event supervisors at other competitions may not.

The capacitors on most DC permanent magnet motors are to suppress the RF (radio frequency) noise generated by the motor. The RF noise can cause problems with solid state circuitry (e.g., transistors/integrated circuits/microcontrollers) that may be used to control the motors. The motors should run equally well with/without the capacitor.

[chalker]

I'm just looking for another opinion on whether or not capacitors are allowed. We are currently using some fans that came with capacitors preinstalled in them. We are using them along with a regular battery, so the capacitors aren't powering the circuit. I submitted a clarification on this exactly 3 weeks ago and unfortunately haven't heard back. Thanks for any advice!

We generally don't give clarifications on trial events, so likely you won't hear back. The capacitors you are referring to are called bypass capacitors, and their function is to filter any AC ripple out of the system that are caused by the motor. It doesn't impact the performance of the motor at all and in fact is only there to protect other components in your circuit. Here's a good discussion with more details: http://www.electro-tech-online.com/elec ... motor.html

Unofficially of course, it's fine to have those capacitors in place.

Edit - ninja'd by Erv;) Ditto what he said above.