Go to Post You know it’s a tough game when you see a bearing on the floor. - D.Allred [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 18-02-2009, 11:03
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: Weird issue with the power distribution block

Just so that we don't confuse anyone, the diodes are speced at 1V@20 amps and 1.25V@40 amps each when forward biased. So even if you could drive the motors at full RPM (highly doubtful) then the diodes would drop at least 2 volts in the speed controller. Remember that the bridge would have two diodes in series with the power supply input pins plus the 0.0005 ohm resistor in the Jaguar negative lead plus the wiring resistance. It is unlikely that you could provide enough power to light up the power convertors for the Crio but you might. Just not long enough for any of the system to boot.
__________________
Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
________________________
Storming the Tower since 1996.
  #17   Spotlight this post!  
Unread 18-02-2009, 11:51
ZInventor's Avatar
ZInventor ZInventor is offline
Registered User
AKA: Zeno Le Héricy
FRC #2915 (Riverdale Robotics Pandamonium)
Team Role: Alumni
 
Join Date: Feb 2008
Rookie Year: 2000
Location: Portland Oregon USA
Posts: 247
ZInventor is just really niceZInventor is just really niceZInventor is just really niceZInventor is just really nice
Re: Weird issue with the power distribution block

Quote:
Originally Posted by Al Skierkiewicz View Post
When you push a robot, the motors begin to act like a generator. The speed controllers (both Victors and Jaguars) use power FETs that have a diode internal to the devices. As you generate current in the motors, that current forward biases the diodes in the FETs and since they are in a bridge configuration, power is back fed to the electrical system. There is no way you can generate enough current to back feed a full 12 volts to the system, but you can generate enough to light some LEDs and make it look like you have an electrical problem. All of this is normal.
odd, we've gotten ALL SYSTEMS to boot up while pushing the bot!

by that i mean, we had connection between the bot and DS without the battery being plugged in! the station read 12.24 volts at peak (which lasted about a minute)

needless to say, i was exhausted after pushing the robot that long.

-Z
__________________
[center]
  #18   Spotlight this post!  
Unread 08-03-2009, 18:32
sparkscarz's Avatar
sparkscarz sparkscarz is offline
Registered User
FRC #1219 (Iron Eagles)
Team Role: Mechanical
 
Join Date: Mar 2009
Rookie Year: 2007
Location: Toronto,Ontario,Canada
Posts: 11
sparkscarz is an unknown quantity at this point
Send a message via MSN to sparkscarz
Re: Weird issue with the power distribution block

nice
!
__________________
.::S::: P:::A:::R:::K:::Y::.

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

Similar Threads
Thread Thread Starter Forum Replies Last Post
Splitting the Rockwell Power Distribution Block aaeamdar Electrical 4 04-02-2008 08:26
Power Distribution Block kE7JLM Electrical 4 17-01-2008 08:48
Power Distribution Block.. beemgruem Electrical 21 11-01-2008 08:11
Problems With The Power Distribution Block sanddrag Electrical 26 27-03-2007 23:11
Stinger Fuse Block and Power Distribution Block Don Wright Electrical 2 30-03-2004 10:45


All times are GMT -5. The time now is 21:00.

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