Wierd application, hypothetical question.

[Eric Bryant]

> 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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