Rookie Electrical Questions

Yes, that is the best advice you can get. keep your electronics organized and very accessible. (also have plenty of extra PWM’s)

also this may come in handy.

Make sure you really understand what’s going on in the power distribution diagram. If there’s something there that you can’t figure out after reading through the rules and the tips and good practices, ask.

Correctly stripping and crimping the wires is the most essential skill. Also make sure you put enough tension on the screw connections on the Power Distribution Block and the Maxi Block. All of your connections should pass the “jiggle test” – if you jiggle the wire a bit, it shouldn’t pull loose. If it doesn’t pass the jiggle test, it’s likely to work loose in competition, which can result in your robot being disabled, becoming immobile, or, in extreme cases, catching fire. Use the proper gauge wire for the breaker protecting the circuit (bigger wire is ok if it fits, but will cost you weight).

We’re using a lot of current here, so don’t skimp on the electrical tape to cover any exposed conductor, particularly your battery terminals once you’ve got the Andersen connector hooked up.

Make sure the main breaker button is always easily accessible in case you need to do an emergency shutdown (you need to be able to get to it without having to remove a cover first, but you’ll want to position it so that other robots/trackballs aren’t going be able to accidentally shut you down).

Make sure you leave enough room by the robot controller to be able to get the serial cables in and out – those bulky connectors are not terribly maneuverable. (That’s the mistake we made as rookies.)

Label wires at both ends, especially the PWM cables to the motors. A labelmaker is your best friend.

You’re going to want to build or buy a disable/autonomous mode switch to hook to the OI for testing purposes. During actual matches, the field will take care of that for you, but for practice, you’ll need a set of switches.

Yes, a disable/autonomous switch comes in handy. I think the wiring diagram is on the IFI site.

I was not aware you could buy one though.

I know AndyMark had one last year they have a clean design and are reasonably priced.

yes, here it is

As pointed out, reading the robot section and Tips and Guidelines are the best start for rookie teams. If you have further questions, you may ask here or PM me and I will try to answer your direct questions.
Please follow the guide for wire size selection as it closely relates to the breakers you use in your design. My recomendations are to feed all Chalupa motors (CIM), Fisher Price and the compressor with #10 wire as short as possible. Use the terminal block to distribute loads and returns so that currents are not shared in the same wire. Above all, any wire used in the terminal block must be stripped 5/8" before insertion. Any less and you will push the wire out of the terminal when you tighten the screws.

Finally, the WPI site should have some of the rookie workshop presentations up in a few days. When they are posted I will alert you here. There is an electrical presentation in PowerPoint that will be available.

One other good practice, if you have time (ha): Read Al’s posts (you can click to get a list from his profile or postbit). There are many electrical nuggets of wisdom tucked in between his caption contest entries. :wink:

That is not true:

(Emphasis mine)

You may want to bring a printout of this rule with you though, it is very possible to get inspectors who don’t know the rules very well (I’ve had it happen at least twice). Also, based off of the posts on CD, tape-related rules seem to be the most inconsistently enforced of the inspection rules.

So that no one will be confused…
The no duct tape rule comes from on high and is not part of the robot rules. It is a well known and long held belief that Dean does not want duct tape to appear on FIRST robots. Other adhesive backed materials will be evaluated per the rules by your inspectors.

To answer all of your questions and even more please click on the following link:

That link is a presentation to help teach/show all rookies how the electronics should be done, or at least gives examples to be used as a guideline for your own robot.


Here’s a link to the IFI website’s circuit diagram … CLICKY

This is a great place to start after you read the manuel. One of our mentors is a master electrican and he expects perfection on the board. He should actually be part of an inspection crew. Good luck and have a great time this year!

Sorry to contradict Al, but this one needs to be emphasized: the ONLY official rules are the ones published by FIRST. There are no “secret” or “hidden” rules. If it does not say it in the manual, it isn’t a rule. The idea that “you can’t have duct tape anywhere on the robot because Dean doesn’t like it, and that is all the justification we need” is an urban legend that needs to be killed immediately. If inspectors are enforcing this legend, then they need to be - politely and respectfully - informed that they are in error and their belief in the “rule” is incorrect.


whatever in 2006 some referee made us take the ducttape lables off of our robot

I’m not debating that that happened. In 2005 our inspector at the Championship made us rewire all our Victor fans because we had wired them per IFI’s instructions, which was a practice s/he objected to (The electronics were massive rats nest after that little adventure). We’ve had a pair inspectors spend quite a while examining a FP gearbox while consulting back and forth with each other to determine if a little shaving/sanding in order to mount it was legal (when the rules clearly stated we could do pretty much whatever we wanted with the gearbox). It is best to go into an inspection knowing the rules very well, rule knowledge varies from inspector to inspector; all you can be certain of is that you know that you built your robot to the rules, and have the evidence to prove it.

big advice: Use as little wire as possible, plan out what will go where ASAP, and integrate it well into your design. finding out you need to run cable to the top of a 8ft lift in week 5 is not fun…

One thing you can use instead of duct tape that looks quite good is what we used to label our PWM’s is label tape then covered in clear shrinkwrap. We never had any complaints on it and it makes it quite visible to what cable it is.

I stand guilty but now corrected.

Just to clarify this further, Shrinkwrap is not an adhesive at all. Just a Substance that shrinks with very high heats. It is technicly just a tube that shirnks. So Yea.

im new this year too and really the best thing to do is read through the rules and make sure you understand them and also listen to your mentors, you can learn alot from them