globe motors

Help!! Can anyone tell me if we can connect the globe motor to spikes instead of the speed controller?

yes.

any place where i find that in the rules

Im not positive… i dont have the rule book in front of me right now, but I am 95% sure that ALL motors must be connected to the victors- no matter if you just need an on/off switch or a true speed control.

that is not true.

only the fisher-price and CIM motors must be connected to Victors, as per the Electrical section rules:

http://www2.usfirst.org/2005comp/Section_5-The_Robot.pdf

<R78> CIM motors and Fisher-Price motors must be connected to Speed Controllers. They may not be
connected to Relay Modules.

From Robot Section 5

CIM motors and Fisher-Price motors must be connected to Speed Controllers. They may not be connected to Relay Modules.

EDIT, looks like I got beat to it. Anyhow, window, globe, and van door may connect to relays.

i need to know about the GOBLE

since they only mention that CIM and FPs must be connected, that means that other motors do not have to be connected. in short, you are fine connecting a globe motor to a spike.

I concur. Unlike in prior year’s this year FIRST has not been as explicit as they have in past years about what can power what and which fuses with what motors, ect.

The closest they have come is listing two motors that a Spike CANNOT drive (namely the CIM and the FP). They have also said that you must use a 20A breaker with the Spike (probably to keep the contacts from welding closed on the Spike).

What is not forbidden is allowed. So… You CAN use the Spike to drive a Globe motor provided you follow the other applicable rules (wire gage, breaker size, etc.).

Joe J.

thanks for clearing that up- that will save us a couple hundred bucks buying more victors!! :smiley:
j

Once again in 2005 FIRST has released an electrical diagram/schematic for use in aiding to your design. This document is located at http://www2.usfirst.org/2005comp/Drawings/2005_ROBOT_POWER_DISTRIBUTION.pdf. In this document it shows the Globe Motors connected to a victor for control. As the Spike Relays will work to control the Globe Motor that is included in the 2005 FRC KOP, I would highly recommend you though to use a Victor 884 to control the Globe motor.

There’s absolutely no reason to use a speed controller if all you need is for the motor to turn on and off. It’s just a waste of money.

And weight :stuck_out_tongue:

To follow up on Dr. Joe’s post, if you really don’t know what you’re doing, I’d suggest going by the electrical rules from 2004. You can read them here: http://www.team229.org/fm/2004/5.2.7 They are more restrictive, but that will save you if you don’t know what you are doing.

The reason they didn’t use to allow the globe motors to be hooked up to spikes is the spikes are only rated for 20 amps, while the globes draw a little more then that at stall. If you do want to use a spike for the globe motor, make sure the mechanical design is such that you will never stall the globe motor. Better yet, just use a speed controller.

i definitely agree with joe - you should follow the 2004 guidelines unless you know exactly what your doing.

chances are if you hoked up your globe motor to a spike it would work perfectly, and you wouldn’t worry about it until it stalled. when a motor stalls, or stops turning while power is still applied, it draws the most current (thus cheap motors are rated at the no-load current and nice motors are rated at the stall current) possible thorough its windings. as previously stated, the globe motor stalls at slightly above 20 amps.

without bringing the engineering team to tears, it is very hard to stall a motor in the shop, but incredibly easy to stall it in the heat of the competition. testing the electronics extensively before the bot ships is very important, because if the motor stalls for the first time in competition, the 20 amp automotive fuse (not the breaker) will probably blow. this will leave your robot motor-less and probably in bad shape. then you will have to spend time in the pits riping your bot apart to replace the fuse (this happened to us 2 years ago). we didn’t bring any extras so we had to send people out to find an auto shop… i think you get the picture :smiley:

so unless your sure that the motor will never stall, or you have a 15 amp breaker on the circuit, don’t use the spike – its possible, but a bad idea.

Thanks for the information and great explanation. It really cleared the question up for us. Have a great day!! :o

Just some things i saw while reading FIRST Guidelines, Tips, & Good Practices in section 5 of the Manual If you want to verify it starts at page 21 and continues on from there here is the link : http://www2.usfirst.org/2005comp/Manuals/Guidelines_C.pdf

also