Go to Post Everyone together now, say 'thank you'. - ebarker [more]
Home
Go Back   Chief Delphi > Technical > Electrical
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Closed Thread
Thread Tools Rate Thread Display Modes
  #16   Spotlight this post!  
Unread 30-03-2011, 00:41
AlDee AlDee is offline
Registered User
FRC #1099
 
Join Date: Mar 2011
Location: Connecticut
Posts: 31
AlDee is an unknown quantity at this point
Re: Homemade resitor

Quote:
Originally Posted by EricH View Post
I could argue that point.

I have a 6" connection. I connect the two points with 10' of wire. Is it still being connected? Absolutely. Is there a lot more resistance than if I only used 6" of wire? Yep.

<R92> does not say that you can't make some other part out of the stuff in it. For example, I could use the rubber bands and surgical tubing to make a nice powerful torsion spring to store energy for latching on to the pole. Is it legal, despite springs not being on the list? Yep. (Now, if I powered vertical motion with it, then I'm illegal under a different rule.)

So, if I can take the 18-gauge wire, connect one end to one connection, connect the other end to the other connection, and bundle the rest safely in the middle (using legal material for the bundling), I just made a resistor out of 100% legal material. The resistor should be legal.

However, again, I am not a source of official answers. The Q&A is, and the inspectors at your event are. If you would like to say what the resistor is used for, then there may be other ways to do that that are clearer with respect to the rules.
I would agree. Any wire, 6 inches or 10' has some resistance. So, I cannot see how a 10' piece could be disqualified. But your point is taken on being up to the the event inspectors. In 2009, our front bumpers failed inspection at the championship, because the plywood backing inside was a half inch shorter than the minimum, even though the bumpers themselves were technically the correct length, and they had previously passed inspection at the regional. In the end it came down the the inspector's interpretation of the rules, even though there was no rule that specifically said the internal backing material had to be a specific length.
  #17   Spotlight this post!  
Unread 30-03-2011, 00:44
Mr V's Avatar
Mr V Mr V is online now
FIRST Senior Mentor Washington
FRC #5588 (Reign)
Team Role: Coach
 
Join Date: Feb 2011
Rookie Year: 2009
Location: Maple Valley Wa
Posts: 997
Mr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond repute
Re: Homemade resitor

Quote:
Originally Posted by NOV8R View Post
Al, we never reversed the voltage to the motors. We simply added additional resistance in the circuit to reduce power. The reduced power wasn't enough for the minibot to maintain position on the pole and it would decend. Yes, shorting the motor leads (what we are now doing) is working well also.
Well that explains why you were heating the motors up, I'm surprised you didn't burn them up back driving a powered motor.
  #18   Spotlight this post!  
Unread 30-03-2011, 00:46
AlDee AlDee is offline
Registered User
FRC #1099
 
Join Date: Mar 2011
Location: Connecticut
Posts: 31
AlDee is an unknown quantity at this point
Re: Homemade resitor

Quote:
Originally Posted by EricH View Post
I could argue that point.

I have a 6" connection. I connect the two points with 10' of wire. Is it still being connected? Absolutely. Is there a lot more resistance than if I only used 6" of wire? Yep.

<R92> does not say that you can't make some other part out of the stuff in it. For example, I could use the rubber bands and surgical tubing to make a nice powerful torsion spring to store energy for latching on to the pole. Is it legal, despite springs not being on the list? Yep. (Now, if I powered vertical motion with it, then I'm illegal under a different rule.)

So, if I can take the 18-gauge wire, connect one end to one connection, connect the other end to the other connection, and bundle the rest safely in the middle (using legal material for the bundling), I just made a resistor out of 100% legal material. The resistor should be legal.

However, again, I am not a source of official answers. The Q&A is, and the inspectors at your event are. If you would like to say what the resistor is used for, then there may be other ways to do that that are clearer with respect to the rules.
I would agree. Any wire, 6 inches or 10' has some resistance. So, I cannot see how a 10' piece could be disqualified. But your point is taken on being up to the the event inspectors. In 2009, our front bumpers failed inspection at the championship, because the plywood backing inside was a half inch shorter than the minimum, even though the bumpers themselves were technically the correct length, and they had previously passed inspection at the regional. In the end it came down the the inspector's interpretation of the rules, even though there was no rule that specifically said the internal backing material had to be a specific length.
  #19   Spotlight this post!  
Unread 30-03-2011, 00:53
AlDee AlDee is offline
Registered User
FRC #1099
 
Join Date: Mar 2011
Location: Connecticut
Posts: 31
AlDee is an unknown quantity at this point
Re: Homemade resitor

Quote:
Originally Posted by Mr V View Post
If your minibot doesn't back drive after it's collision with the trigger then a 4 way switch can be used to put one motor in "brake" mode while having the other drive reverse.
What type of 4 way switch are you using? Is it a light switch? I took the term "Standard Light Switch" to mean a single pole single throw switch. Does a 2-way or 3-way switch qualify as a standard light switch?
  #20   Spotlight this post!  
Unread 30-03-2011, 01:06
The Lucas's Avatar
The Lucas The Lucas is offline
CaMOElot, it is a silly place
AKA: My First Name is really "The" (or Brian)
FRC #0365 (The Miracle Workerz); FRC#1495 (AGR); FRC#4342 (Demon)
Team Role: Mentor
 
Join Date: Mar 2002
Rookie Year: 2001
Location: Dela-Where?
Posts: 1,564
The Lucas has a reputation beyond reputeThe Lucas has a reputation beyond reputeThe Lucas has a reputation beyond reputeThe Lucas has a reputation beyond reputeThe Lucas has a reputation beyond reputeThe Lucas has a reputation beyond reputeThe Lucas has a reputation beyond reputeThe Lucas has a reputation beyond reputeThe Lucas has a reputation beyond reputeThe Lucas has a reputation beyond reputeThe Lucas has a reputation beyond repute
Send a message via AIM to The Lucas
Re: Homemade resitor

Quote:
Originally Posted by AlDee View Post
In 2009, our front bumpers failed inspection at the championship, because the plywood backing inside was a half inch shorter than the minimum, even though the bumpers themselves were technically the correct length, and they had previously passed inspection at the regional. In the end it came down the the inspector's interpretation of the rules, even though there was no rule that specifically said the internal backing material had to be a specific length.
In that anecdote, it didn't come down to some inspector's arbitrary interpretation. That was the rule as originally written, immediately clarified by the GDC in the Q&A (below), and reemphasized in Team Update #2
Quote:
Minimum Length Bumper Segments
Minimum Length Bumper Segments
Posted by FRC1114 at 01/07/2009 05:58:04 pm
<R08>-A states "BUMPERS must be build in segments, with a minimum length of six inches..."
<R08>-J states "Corners and joints between BUMPER segments may be filled with short vertically oriented pool noodle..." Will bumpers be measured by the length of the plywood backing, or the plywood backing + any vertically oriented pool noodles used for corners? i.e. Can we have a minimum length 6" bumper, with less than 6" of plywood.
Cheers,
Re: Minimum Length Bumper Segments
Posted by GDC at 01/09/2009 10:11:08 pm
Please refer to Team Update #2. As indicated in Rule <R08>, BUMPERS must include a solid plywood backing (as well as the pool noodles, clamping angles, and fabric cover). The length of the the bumper assembly that includes all of these items is what determines the "bumper length."
__________________
Electrical & Programming Mentor ---Team #365 "The Miracle Workerz"
Programming Mentor ---Team #4342 "Demon Robotics"
Founding Mentor --- Team #1495 Avon Grove High School
2007 CMP Chairman's Award - Thanks to all MOE members (and others) past and present who made it a reality.
Robot Inspector
"I don't think I'm ever more ''aware'' than I am right after I burn my thumb with a soldering iron"
  #21   Spotlight this post!  
Unread 30-03-2011, 02:28
Mr V's Avatar
Mr V Mr V is online now
FIRST Senior Mentor Washington
FRC #5588 (Reign)
Team Role: Coach
 
Join Date: Feb 2011
Rookie Year: 2009
Location: Maple Valley Wa
Posts: 997
Mr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond repute
Re: Homemade resitor

Quote:
Originally Posted by AlDee View Post
What type of 4 way switch are you using? Is it a light switch? I took the term "Standard Light Switch" to mean a single pole single throw switch. Does a 2-way or 3-way switch qualify as a standard light switch?
Well our robot does back drive so we aren't using a 4 way. Unfortunately the rules changed a couple of times so there is lots of confusion over this issue. So they do allow pretty much any sw designed for wall box mounting to 2-way, the most common sw, as well as 3 and 4-way switches are legal.
To cloud things even more household wiring sw terminology is different from other types of wiring terminology. Basicallly in household switches the # before the -way refers to the number of terminals.


To wire it to provide "reverse" to one motor and brake to the other:

A 4-way switch has 2 black color and 2 brass color terminals, so we'll call them bl1, bl2, br1, and br2. Connect B+ to bl1 and B- to bl2. Connect forward + for motor a and b to br1 connect motor forward - for motor a to br 2 and motor forward - to bl2.

In sw position 1 terminal bl1 is connected to br1 and bl2 is connected to br2. Flip the sw to position 2 and bl1 connects to br2 and bl2 connects to br1. So in 1 position both motors are powered forward and in the other position motor a is powered reversed and both motor b leads are connected together which just so happens to be also connected to battery - which plays no part in that circuit. both of the brake motor leads could just as well be connected to battery +, and it would still work the same.

However to have a minibot that doesn't back drive it needs to have a high effective gear reduction and be very light.
  #22   Spotlight this post!  
Unread 30-03-2011, 08:50
Unsung FIRST Hero
Al Skierkiewicz Al Skierkiewicz is offline
Broadcast Eng/Chief Robot Inspector
AKA: Big Al WFFA 2005
FRC #0111 (WildStang)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 1996
Location: Wheeling, IL
Posts: 10,798
Al Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond repute
Re: Homemade resitor

Chuck,
Now I see. Interesting idea. I haven't heard of anyone doing that so I was having a hard time understanding your description.
__________________
Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
________________________
Storming the Tower since 1996.
  #23   Spotlight this post!  
Unread 30-03-2011, 09:05
Teched3 Teched3 is offline
Hodge1
FRC #0175 (BuzzRobotics)
Team Role: Mentor
 
Join Date: Apr 2006
Rookie Year: 1996
Location: Connecticut
Posts: 319
Teched3 has much to be proud ofTeched3 has much to be proud ofTeched3 has much to be proud ofTeched3 has much to be proud ofTeched3 has much to be proud ofTeched3 has much to be proud ofTeched3 has much to be proud ofTeched3 has much to be proud ofTeched3 has much to be proud of
Smile Re: Homemade resitor

What does your minibot weigh?

Quote:
Originally Posted by Mr V View Post
Well our robot does back drive so we aren't using a 4 way. Unfortunately the rules changed a couple of times so there is lots of confusion over this issue. So they do allow pretty much any sw designed for wall box mounting to 2-way, the most common sw, as well as 3 and 4-way switches are legal.
To cloud things even more household wiring sw terminology is different from other types of wiring terminology. Basicallly in household switches the # before the -way refers to the number of terminals.


To wire it to provide "reverse" to one motor and brake to the other:

A 4-way switch has 2 black color and 2 brass color terminals, so we'll call them bl1, bl2, br1, and br2. Connect B+ to bl1 and B- to bl2. Connect forward + for motor a and b to br1 connect motor forward - for motor a to br 2 and motor forward - to bl2.

In sw position 1 terminal bl1 is connected to br1 and bl2 is connected to br2. Flip the sw to position 2 and bl1 connects to br2 and bl2 connects to br1. So in 1 position both motors are powered forward and in the other position motor a is powered reversed and both motor b leads are connected together which just so happens to be also connected to battery - which plays no part in that circuit. both of the brake motor leads could just as well be connected to battery +, and it would still work the same.

However to have a minibot that doesn't back drive it needs to have a high effective gear reduction and be very light.
__________________
Sweat the details
Why is there never enough time to do it right, but always enough time to do it again!
Even if you're on the right track, if you sit still, you'll get run over!!!
  #24   Spotlight this post!  
Unread 30-03-2011, 12:37
Mr V's Avatar
Mr V Mr V is online now
FIRST Senior Mentor Washington
FRC #5588 (Reign)
Team Role: Coach
 
Join Date: Feb 2011
Rookie Year: 2009
Location: Maple Valley Wa
Posts: 997
Mr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond repute
Re: Homemade resitor

Quote:
Originally Posted by Teched3 View Post
What does your minibot weigh?
~3.1 lbs
Closed Thread


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 19:05.

The Chief Delphi Forums are sponsored by Innovation First International, Inc.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi