Re: [PSUBS-MAILIST] Pulse/Stepping Motors

[Lew Clayman <lew_clayman@yahoo.com>]

--- Adam <adamnr@netrover.com> wrote:
> > What do you know about pulse motors? Is that the same thing as a
> > stepping motor?
> > I bought one and don't know how to use or hook it up.

I believe that a pulse-modulated system works as follows:

The power is provided to the motor in pulses, at some very high frequency.  What the motor "sees"
is close enough to continuous power - because of the high frequency - that it doesn't "notice" the
difference.  The frequency never changes.  Internal electronics regulates all of this.

What does change is the percentage of each cycle which is positive voltage, vs zero voltage.  If
the pulse is "100% on" then the motor "sees" maximum power, power all the time.  If it's 50% on,
then the motor gets power half the time, or effectively half power, so it spins slower.  All zero,
of course, is all zero and no power.  You can set the percentage "on" anywhere in between.  Think
of a rapidly blinking light, blinking so fast that you can't see the blinks, just the light, which
looks dimmer as the blink-ons become shorter than the blink-offs.

Why this is "good" is because the battery is only discharged as needed, that is to say all (pretty
much) of  the power drawn from the battery goes directly (pretty much) to the motor.  The other
approach, which is to put a variable resistor between  the battery & the motor, is less efficient
because the battery is "drained" at full blast the whole time, but some of the power is diverted
(wasted, dissapated) by the resistor.

Manually pulsing the switch on a motor set to full speed, as suggested, is less precise and more
trouble than using a pulsed controller, but amounts to much the same thing.  Maybe there's a
little more start-stop loss, but I suspect only a little.  

-L

 
> 
> Ed,
> 
> Forgive me for answering a question that was not addressed to me but I feel
> I accel in this field more than other and it's a chance for me to really
> contribute.
> 
> A stepper motor is used in industry for systems that require a lot of
> control.  You'll notice that out of the housing you'll have many wires,
> unlike the conventional motor which only has two.  There will usally be a
> black wire, and a series of muti coloured wires.  Usally about four or five.
> 
> The way one hooks it up, it a little more complicated the the standard
> motor.
> 
> The black must be grounded.  and the remaining wires must be turned on in
> the correct sequence to make it turn.
> 
> example:  five wires, one black, one red, one blue, one green, and one
> yellow.
> 
> To make one revolution with this hypotheticle motor, ground the black and
> then  the system has to apply power to red, then blue, then green and then
> yellow.  Never at the same time but pulse each one....  One controls the
> speed by cutting the delay between each pulse.
> 
> I hope this has explained it...  As far as stepper vs. pulse..  I would
> think it's the same thing...   the nomenclature  comming from the "pulsing"
> of the different leads.
> 
> Adam
> 


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          - Traditional Mexican Lyric (La Bamba)
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