Chief Delphi - resistors?

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can resistors be used on the minibot?

Nope, they are not listed in the allowable parts spelled out in <R92>

well the parts list says nothing about electronic components. the rules dont even address them.

Quote:

<R92> The following items are the only permitted materials for use on the MINIBOTS:
A. TETRIX components that are not
in violation of any other rules,
(Tetrix components are listed in
Approved Tetrix Parts at
www.usfirst.org/frc/competitionma
nual),
B. no more than two motors (PN
W739083/W739023) and an
unlimited number of Tetrix
servos),
C. no more than one 12V
rechargeable NiMH battery pack
identical to those supplied in the
FTC kit of parts (PN W739057)
except the 20A fuse may be
replaced with an equivalent type
of lower amperage,
D. No more than one HiTechnic DC
motor controllers,
E. No more than one NXT controller
with the Bluetooth functionality
disabled,
F. Polycarbonate,
G. Polycarbonate glue,
H. Raw welding rod, aluminum
sheet, 90° angle, u-channel, tube,
bar, that is not sold in preperforated or pre-punched form.
I. rivets,
J. non-metallic rope or cord,
K. wire nuts, solder, and crimps,
L. cable ties,
M. limit switches,
N. no more than two common
household light switches,
MINIBOTS will be inspected for the volume constraint by being placed in a five-sided
box with internal dimensions of 12" x 12" x 12". If the lid (the sixth side of the cube)
does not seat properly, the MINIBOT does not pass this part of the MINIBOT
inspection.
If an observation is made that another team’s ROBOT may be in violation of the robot
rules, please approach FIRST officials to review the matter in question. This is an
area where Gracious Professionalism is very important© FIRST 2011 FRC Game Manual, Section 4 – The Robot, Rev L Page 31 of 34
O. electrical hookup wire,
P. non-slip pad,
Q. PVC or CPVC pipe and fittings,
R. PVC cement or cleaner,
S. Mechanical fasteners (e.g.
screws, bolts, etc),
T. Loctite or similar thread-locking
product,
U. Rubber bands,
V. Surgical tubing,
W. Electrical tape and shrink tubing,
X. PWM extension cables,
Y. Universal security clips to hold
the PWM connectors together,
Z. Hook and loop fastener (may not
be used as tape),
AA. Magnets,
BB. NXT compatible sensors and
related connectors/cables,
CC. Grease, and
DD. Non-functional decorations.

Ergo, they cannot be used.

Quote:

Originally Posted by ADTRavenger3585 (Post 1044831)

well the parts list says nothing about electronic components. the rules dont even address them.

I was under the impression that motors, batteries, switches, wire, fuses, etc were all electrical components.

Quote:

Originally Posted by ADTRavenger3585 (Post 1044831)

well the parts list says nothing about electronic components. the rules dont even address them.

The first line says, in effect, "If it's not on this list, you can't use it." Or, to put it another way, "If it's not permitted, it is prohibited, and here's the 'permitted' list".

If only. I'd love to replace that big heavy battery with a 2 oz ultracapacitor. Alas, it would not be legal.

Would it be worth putting in an official Q&A as to whether a resistor extracted from a legal component would itself be legal to use? I don't know which components might have resistors in them. My guess is the answer would be no, but you don't know for sure until you ask. Of course do a search of the Q&A before you ask...

The bigger question is why you would want to use resistors on the minbot, do you want a slow bot? Shunting the motor leads together will make it act as a dynamic brake to slow the descent nicely. The kop limit SW or a household 3 way SW will do it. Diagrams on how to wire it are all over CD. If your bot stays at the top of the power you can use a 4 way SW to reverse 1 motor and put the other in brake mode.

the idea was to wire a resistor into a DPDT switch to control the descent. seeing as resistors are apparently prohibited we just used electrical hook up wire and poly carbonate to make our own resistor. nothing illegal there. :D

Early on in minibot testing we found that if you switched a 4 ohm resistance in series with the motors it slowed the motors and the mini would slowly decend. It also only required a simple lamp switch. We ended up using limit switches and back emf because of "is it legal' issues

Quote:

Originally Posted by ADTRavenger3585 (Post 1045027)

Are you driving down the pole? If you are braking down the pole resistors will actually speed up the descent.

Quote:

Originally Posted by ADTRavenger3585 (Post 1045027)

Although this last part would be using legal parts, it is not needed. Simply short the motor leads to descend slowly.

Bill,
Remember that you would need to supply ~10 amps for two seconds to be sure your minibot would make the top. Could your super cap deliver that constantly over the two seconds?