Wierd application, hypothetical question.

[justin ivan]

Eric,
You are right about the response times of solenoids with regards to load. 
The idea of a PWM driven solenoid is good in theory but seems to be lacking 
in this application. Sure a stepper motor will require some fabbing but an 
me should be able to handle it ok.
Justin
>From: Eric Bryant <BRYANTE at ghsp.com>
>Reply-To: diy_efi at diy-efi.org
>To: "'diy_efi at diy-efi.org'" <diy_efi at diy-efi.org>
>Subject: RE: Wierd application, hypothetical question.
>Date: Wed, 6 Dec 2000 16:35:55 -0500
>
> > From: justin ivan [mailto:vlkslvr at hotmail.com]
> > Subject: RE: Wierd application, hypothetical question.
> >
> >
> >
> > Eric,
> > Everything that you stated about solenoids is indeed
> > accurate, now I don't
> > know that much about voice coil actuators at all BUT you are
> > 100% correct a
> > stepper motor really is the way to go in this case. Do we
> > have an idea of
> > response time required? Solenoid's have a very rapid response
> > time (on the
> > order of 15 microseconds or less in most cases).
>
>You can get solenoids with time constants in the millisecond range, but
>that's usually specified with no load attached.  You'd have to add in the
>inertia of the rest of the system, and of course subtract the load from the
>solenoid force.  It's pretty easy to see that you can shoot your response
>time in the foot once the solenoid is actually in a system (which is just
>fine if you're shooting for a PWM drive freq.).
>
> > Stepper
> > motor is probably a
> > bit slower then this but should fit this app OK
> > Stepper motor is definately they way to go with this
> > application, there are
> > already plenty of circuits designed to control these suckers
> > you just need
> > to do a search. One of the things to look is CNC retrofits
> > for milling
> > machines.
>
>Yea, there's a few circuits, parts, and control algorithms out there, if 
>you
>know where to look.  It's not going to be a simple task by any means, but
>the original poster hinted at some fabrication skills that may come in 
>handy
>on this project.
>
>Eric Bryant
>mailto:bryante at ghsp.com
>http://www.novagate.com/~bryante
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