Servo / Stepper Motor Applications/How To

[matapan]

Beyond lighting and power controlled appliances, alot of applications seem to employ some kind of motor that open and closes things. Things like draperies and blinds, windows, vent registers, etc.

 

Never having dealt with motors of this type before, can anyone direct me to a site that has basic info how to set up and use motors for these kinds of applications?

 

There are specific questions I have about motors:

 

- When does one use a stepper motor or a servo motor? Are there specific circumstances one is used over the other?

 

- Beyond a simple manual on/off function, do these motors have any kind of sense when they should turn off by themselves? I was wondering how certain motors will turn off when a limit has been reached (e.g. when a curtain is fully open or closed). Is this mostly done by resistance or by timing?

 

- Motors have a torque spec that is a number. How does one relate this value to a real world application, whether or not it's enough or more than enough torque for the job?

 

- Are there certain pitfalls to watch out for? If it's going to be automated, it should work pretty reliably and have some kind of fail safe, right?

[apostolakisl]

All of those things you list have pre-built devices specifically for that task with all the limit switches, torque setings and what-not configured.

 

You can make this stuff from scratch. I have made a few things myself. However, I have a workshop with metal working mills, lathes, welding, etc. Plus lots of random shelves full of random things that I modify for a task at hand. I do enjoy seeing what I can build out of the stuff in the workshop that my wife would have thrown away if left to her own. And it takes a lot of time to make these things. I would not go to the trouble to make something for a standard application like closing drapes, it is usually cheaper and definitely a hell-of-a-lot easier to buy the prefab ones.

 

The prefab devices will typically have a dry contact for open/close.