Art Interface Device logo   Project description  Development   Mailing List  Contact


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: AID: Motor Questions

From: cis   cisartsens.org
Date: Wed, 13 Nov 2002 08:05:21 -0800

: Sent via the Art Interface Device mailing list: aid@interaccess.org
: Use your "Reply All" to  reply to the list, "Reply" for private response

> : Sent via the Art Interface Device mailing list: aid@interaccess.org
> : Use your "Reply All" to  reply to the list, "Reply" for private response
> I'm working on a PC parallel port interface to drive some 5V lights and
> some motors.  The logic chips work fine as do the drivers for the lights
> (L293), but I'm having problems with the drivers for the motors (L298),
> which have been unreliable (either I blew them or they were bad).  I chose
> stepper motors because I thought I would get more precise position control
> without having to build any feedback mechanism, but I'm wondering if I
> should go with something simpler and even drive it with a transistor (e.g.
> TIP 127).
It is impossible to drive a step motor with only one transistor

do not use TIP127 that are PNP

you need 4 TIP122 and 4 diodes to drive it
see : http://www.interq.or.jp/japan/se-inoue/e_step.htm
for exemple how to drive  with transistors

but as I read your mail, I m not sure that you use well the L298
that is more for bipolar stepper motors (you can use it

if your step motor have 6 wires it is a unipolar
with ohm meter you need to find two groups of 3 wires that give an answer of some ohm
 exemple A B C and D E F  wires


in the A B C group , you need to find the middle point
with the ohm meter :
 for example you measure
between A and D   infinite
between A and E   infinite
between A and F   infinite

between A and B   0,7ohm
between C and B   0,8 ohm
between A and C   1,5 ohm
in such a case the middle point is B

do the same thing with the second group D E F
suppose that the middle point is E

now you will connect  B and E together to +VCC (5V in your case)

http://www.interq.or.jp/japan/se-inoue/e_step1.htm
give all explanation of the fonctionnement of the motor unipolar with java animations
in your case now,

A is X
C is /X

D is Y
F is /Y

with the L298
you have two bridge
connect A and C to one bridge,
connect D and F to the other bridge
in that case you can use a power of 10Volt for L298
if you let B and E in the air

if you connect B and E to VCC then VCC is only 5 volt


 Now the questions.
> 1) I know that some of you at least are interested in PWM which I assume
> is
> for driving non-stepper motors.  I'm interested in comments on the
> trade-offs between steppers and non.

PWM are for driving continuous motors (it simulate variable continuous voltage via a power interface)
you can t drive Stepper motor directely with it


> 2) I found the steppers (5V 8.5W unipolar) at Active Surplus.  Is there a
> better source for motors?

I m in france I can t help you for that, but I can say that your motor seem to be performant
if you want low cost stepper motor you can find two in old printers

--
cis@artsens.org


:      messages saved at http://www.interaccess.org/aid/list
:      unsubscribe/help requests to mailto:Majordomo@interaccess.org