Go to Post It's wonderful to think of how close together we all grow, win or lose. - Po-ser [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
  #1   Spotlight this post!  
Unread 12-02-2004, 23:11
Dale(294engr]'s Avatar
Dale(294engr] Dale(294engr] is offline
Mentor/Sponsor since '98
FRC #0294 (Beach Cities Robotics)
Team Role: Engineer
 
Join Date: Jan 2004
Rookie Year: 1998
Location: Redondo Beach, CA
Posts: 92
Dale(294engr] is a glorious beacon of lightDale(294engr] is a glorious beacon of lightDale(294engr] is a glorious beacon of lightDale(294engr] is a glorious beacon of lightDale(294engr] is a glorious beacon of lightDale(294engr] is a glorious beacon of light
4 pin EDU PWM out power, red pin2 V in error

Our EDU controller measures 7.2V(to ~8v charged) on both pins 2 & 4.
Pin 2 (red) should be +5v
Pin 4 (unk color) should be 7.2v

Has any other teams observed this problem ?

I was looking for but find no jumper option
(so servo's could use either unreg or reg)

We could have a fault/failure inside the EDU +5v power distribution.

The middle digital IO pin does properly read +5v
(have been using that until problem is resolved)

anyone know if there are separate +5 regs inside EDU ?

Any ideas what the problem is ? or Do other EDU's have it too ?

Beacons w/7.2v to 8V charged,
using this fault would start our ~2X brighter
8v-1.34/33ohms=.2A
where orig design=5v-1.34/33 =.111A

(note IR LED's were tested, forward V=1.34v at .11A dc)
  #2   Spotlight this post!  
Unread 13-02-2004, 00:08
Random Dude Random Dude is offline
Oregon State Head FTA
AKA: Chris
no team (Oregon Robotics Tournament & Outreach Program)
 
Join Date: Aug 2002
Rookie Year: 1998
Location: Oregon
Posts: 142
Random Dude will become famous soon enoughRandom Dude will become famous soon enough
Re: 4 pin EDU PWM out power, red pin2 V in error

Quote:
Originally Posted by Dale(294engr]
Our EDU controller measures 7.2V(to ~8v charged) on both pins 2 & 4.
Pin 2 (red) should be +5v
Pin 4 (unk color) should be 7.2v
Nope, both pins should measure +7.2v ( the current voltage of the battery)

See the EDU referece guide http://www.innovationfirst.com/FIRST...2003-11-14.pdf
  #3   Spotlight this post!  
Unread 13-02-2004, 01:09
Dale(294engr]'s Avatar
Dale(294engr] Dale(294engr] is offline
Mentor/Sponsor since '98
FRC #0294 (Beach Cities Robotics)
Team Role: Engineer
 
Join Date: Jan 2004
Rookie Year: 1998
Location: Redondo Beach, CA
Posts: 92
Dale(294engr] is a glorious beacon of lightDale(294engr] is a glorious beacon of lightDale(294engr] is a glorious beacon of lightDale(294engr] is a glorious beacon of lightDale(294engr] is a glorious beacon of lightDale(294engr] is a glorious beacon of light
Re: 4 pin EDU PWM out power, red pin2 V in error

Quote:
Originally Posted by Random Dude
Nope, both pins should measure +7.2v ( the current voltage of the battery)

See the EDU referece guide http://www.innovationfirst.com/FIRST...2003-11-14.pdf
Thanks for the quick reply RD.

So was the FRC Beacon LED current designed for ~202 mA ea?
(Ipk =8v-1.34VfwdIRled)/33ohms)

and decrease in IR output intesnity as the battery voltage declines ?

A previous poster indicated red EDU PWM = 5v where
Ipk = (5-1.34)/33 = 111 mA each of 4 parallel LEDs ???
  #4   Spotlight this post!  
Unread 13-02-2004, 02:15
Kevin Watson's Avatar
Kevin Watson Kevin Watson is offline
La Cañada High School
FRC #2429
Team Role: Mentor
 
Join Date: Jan 2002
Rookie Year: 2001
Location: La Cañada, California
Posts: 1,335
Kevin Watson has a reputation beyond reputeKevin Watson has a reputation beyond reputeKevin Watson has a reputation beyond reputeKevin Watson has a reputation beyond reputeKevin Watson has a reputation beyond reputeKevin Watson has a reputation beyond reputeKevin Watson has a reputation beyond reputeKevin Watson has a reputation beyond reputeKevin Watson has a reputation beyond reputeKevin Watson has a reputation beyond reputeKevin Watson has a reputation beyond repute
Re: 4 pin EDU PWM out power, red pin2 V in error

Quote:
Originally Posted by Dale(294engr]
A previous poster indicated red EDU PWM = 5v where
Ipk = (5-1.34)/33 = 111 mA each of 4 parallel LEDs ???
OH CR...UD! Mea Culpa, Dude. I'm sorry, you were correct and I laid down a healthy dose of... Er,... Well, you know. Anyway, the LEDs should be okay (I've driven them up to 800mA with the beacon waveforms), but now I'm somewhat worried about the power rating on the resistors. Some teams got 1/2 watt, but as I found out a few days ago, others got 1/4 watt (ouch!). I guess I'll add an entry to the FAQ addressing the resistors (which may be another good, but unintended, source of infrared energy ).

-Kevin
__________________
Kevin Watson
Engineer at stealth-mode startup
http://kevin.org
  #5   Spotlight this post!  
Unread 13-02-2004, 03:03
Dale(294engr]'s Avatar
Dale(294engr] Dale(294engr] is offline
Mentor/Sponsor since '98
FRC #0294 (Beach Cities Robotics)
Team Role: Engineer
 
Join Date: Jan 2004
Rookie Year: 1998
Location: Redondo Beach, CA
Posts: 92
Dale(294engr] is a glorious beacon of lightDale(294engr] is a glorious beacon of lightDale(294engr] is a glorious beacon of lightDale(294engr] is a glorious beacon of lightDale(294engr] is a glorious beacon of lightDale(294engr] is a glorious beacon of light
Re: 4 pin EDU PWM out power, red pin2 V in error

Quote:
Originally Posted by Kevin Watson
OH CR...UD! Mea Culpa, Dude. I'm sorry, you were correct and I laid down a healthy dose of... Er,... Well, you know. Anyway, the LEDs should be okay (I've driven them up to 800mA with the beacon waveforms), but now I'm somewhat worried about the power rating on the resistors. Some teams got 1/2 watt, but as I found out a few days ago, others got 1/4 watt (ouch!). I guess I'll add an entry to the FAQ addressing the resistors (which may be another good, but unintended, source of infrared energy ).

-Kevin
Kevin,
retraction appreciated, Thanks

There should be no problem with 1/4 W resistors
pulsed 40kHz & 1-2mS burst
(5% overall duty 1mS 40 pulses 50-50 & 10% 2mS 80 pulses)

WC .2A^2*.1duty*33 = .132W ~53% utilization of quarter Watt resistor.

at least not until they are accidently driven w/DC. (EDU pgm croak)

.2A^2*1duty*33 = 1.32W ~5X that quarter Watt resistor
that unmistakable smell of carbon burning, ahhh

that makes my proposed 4x LED series string + 1 current limit resistor
(or 2 junct tran+resistor regulator)
(5.36v from 7-8 Vbatt) look a bit better. least on paper.

We'll have to deal with the IR dropoff with dwindling battery supply,
or use an AC adapter, not a big deal.
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
PWM port power rust710 Electrical 10 21-02-2003 13:56
Ok, so YOU design the 2003 game... dlavery General Forum 157 07-01-2003 23:55
Ugh...PWM pin vs. Speed Controller archiver 2001 1 24-06-2002 00:27


All times are GMT -5. The time now is 19:32.

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