RE: [CAD_CAM_EDM_DRO] Re: steppers best?

Thanks guys - I'm sooo thankful for the internet and either other time
zones, OR insomniacs, whichever allows me to leave a ? at 11:34PM pick up
some suggestions by 05:00 the next AM :o))

You raise good questions, that I didn't cover in the initial request for
info.

Time - is actual time vs predicted time, so accuracy is more important than
speed, IF the trip is made in less than 45 seconds (for 5 - 10 M), which
seems easy w/o ramp up.dn..

Electronics and $ - I need to check on the both of these, but I should think
that $50 wouldn't be outside the rules, and my reading of the rules does not
outlaw electronic timers or line followers (there's an "on target" component
to the scoring) and in the past, they've specifically outlawed such devices
(in an event called "Wheeled Vehicle" vs this year's event called "Electric
Vehicle"), so I think they were trying to open this event to novice
electronics kids (and mentors :o)) ).

RE LCD - Well, I was thinking we might get away with just a pulser and
translator based on 555 and 5804's and L297/8N drivers, but that number of
steps display might be TOO COOL to pass up! We have some LCDs and 7 segment
LEDs in our "salvage" box, but might be a bit of a challenge to figure out
in parallel with the actual "let's drive a certain distance" problem. Hmm -
thanks for this and other suggestions!

So looks like we are on right path, if I understand feedback correctly.

Chuck Merja
<http://www.srvscience.org> www.srvscience.org

_____

From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of Graham Stabler
Sent: Wednesday, October 17, 2007 3:11 AM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Re: steppers best?

I think it is worth a go, if speed is not essential then you can
pretty much just set the micro to produce x number of pulses which
will equate to a distance related to the gear ratio and wheel diameter.

For higher speed an acceleration and deceleration phase would be a
good idea, perhaps just a look up table in this case, adjusting the
coast distance to match the required destination.

But first you need a stepper motor driver that will work with your motors.

If the motors are bipolar and require less than 0.75 amps per phase
you might consider these:

http://www.sparkfun
<http://www.sparkfun.com/commerce/product_info.php?products_id=8368>
.com/commerce/product_info.php?products_id=8368

I think they look just the ticket for small automation and robotics.

Graham

Messages
<http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/message/93998;_ylc=X3oDMTM1ZG
prZmFxBF9TAzk3MzU5NzE0BGdycElkAzE3NjI4OQRncnBzcElkAzE3MDUwNDE5OTIEbXNnSWQDOT
QwMDAEc2VjA2Z0cgRzbGsDdnRwYwRzdGltZQMxMTkyNjEyMjU3BHRwY0lkAzkzOTk4> in this
topic (0)
<http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/post;_ylc=X3oDMTJwbmM5c3NoBF9
TAzk3MzU5NzE0BGdycElkAzE3NjI4OQRncnBzcElkAzE3MDUwNDE5OTIEbXNnSWQDOTQwMDAEc2V
jA2Z0cgRzbGsDcnBseQRzdGltZQMxMTkyNjEyMjU3?act=reply&messageNum=94000> Reply
(via web post) | Start
<http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/post;_ylc=X3oDMTJkcnI1OHU4BF9
TAzk3MzU5NzE0BGdycElkAzE3NjI4OQRncnBzcElkAzE3MDUwNDE5OTIEc2VjA2Z0cgRzbGsDbnR
wYwRzdGltZQMxMTkyNjEyMjU3> a new topic
Messages
<http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/messages;_ylc=X3oDMTJkNDk1aHF
iBF9TAzk3MzU5NzE0BGdycElkAzE3NjI4OQRncnBzcElkAzE3MDUwNDE5OTIEc2VjA2Z0cgRzbGs
DbXNncwRzdGltZQMxMTkyNjEyMjU3>
_


[Non-text portions of this message have been removed]