Go to Post In my book the team building experience of the kids training the engineers in the operations on the field would be invaluable. It might not get a trophy but you win far more in the long run. - Wayne C. [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

 
 
 
Thread Tools Rate Thread Display Modes
Prev Previous Post   Next Post Next
  #10   Spotlight this post!  
Unread 24-01-2002, 01:20
Kris Verdeyen's Avatar
Kris Verdeyen Kris Verdeyen is offline
LSR Emcee/Alamo Game Announcer
FRC #0118 (Robonauts)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 2001
Location: Houston, TX
Posts: 699
Kris Verdeyen has a reputation beyond reputeKris Verdeyen has a reputation beyond reputeKris Verdeyen has a reputation beyond reputeKris Verdeyen has a reputation beyond reputeKris Verdeyen has a reputation beyond reputeKris Verdeyen has a reputation beyond reputeKris Verdeyen has a reputation beyond reputeKris Verdeyen has a reputation beyond reputeKris Verdeyen has a reputation beyond reputeKris Verdeyen has a reputation beyond reputeKris Verdeyen has a reputation beyond repute
Here's a circuit I banged out that might be able to help you.

It has a small current sensing resistor in series with the battery and circuit breaker. The voltage across the resistor, which is proportional to the battery current, is determined and amplified by a difference amplifier circuit that has a gain of 25, which allows the 1 milliohm resistor to fill the available range on the A/D input. (200A through the circuit corresponds to 255 A/D counts). And the wheel on the bus goes round and round.

You might want to throw on an output filter to remove the PWM ripple, and perhaps another gain stage to fine tune the circuit's range, but it should work reasonably well now.

Please note that Digikey doesn't have any 1 milliohm resistors that can handle enough power to work here - so you have to 'make' your 1 milliohm resistor from five 5mOhm precision resistors, or ten 10mOhm precision resistors (in parallel). Five of these would be able to handle 24W continuously, which is short of the 40W required for the anticipated 200A spikes, but I think they would hold up in practice, because the average power dissapated would be well below 24W.

If you have any questions, let me know. I know that I didn't document the image too well, but it shouldn't be too hard to get the general idea.
Attached Thumbnails
Click image for larger version

Name:	current sensing circuit.jpg
Views:	160
Size:	121.0 KB
ID:	291  
__________________
...Only a few people are awake and they live in a state of constant total amazement. -JP Shanley, Joe vs. the Volcano

Last edited by Kris Verdeyen : 24-01-2002 at 01:25.
 


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
How to access other Digital inputs on OI? DougHogg Electrical 2 12-03-2003 13:57
Robot Controller Digital Input crazycliffy Electrical 11 16-02-2003 04:28
Digital inputs, bandwith, errors? Micah Brodsky Programming 7 20-01-2003 16:08
Analog vs Digital inputs? f22flyboy Programming 8 08-11-2002 22:18
Serious Controller Ideas archiver 1999 28 23-06-2002 23:01


All times are GMT -5. The time now is 19:03.

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