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Automatic door

ventsyv

Dec 3, 2014
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My 2 year old is crazy about doors, so for Christmas I want to build him an automatic sliding door.
I'm thinking an aluminum frame with a Plexiglas pane on some sort and aluminum rail.

I was thinking to get a motion sensor and hook it up to a step motor but don't have any idea what kind of motor and what kind of gears I need. Maybe use a raspberry pi to control how long the slide the door.

I don't have much experience with electronics, last time I've done anything like that was in my basic circuits class in college, so any pointers are much appreciated.
 
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Bluejets

Oct 5, 2014
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Small dc motor with a gearbox ( ebay...cheap) driving a rope around some pulleys, forward and reverse momentry switches, limit switches for each end of travel that automatically select the other direction.
So either push and hold forward button, door moves off that limit or use a latching contact to hold-in the button press.
When the door reaches the other end. the limit flips the operation to the other direction and stops the motor. One needs to press the other direction momentry switch to get the door to move again.
If you wish to stop the door by releasing either button, forget the latching contacts.

No need for microcontrollers.
 

ventsyv

Dec 3, 2014
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What kind of DC motor will you recommend? 6V or 12V? I don't know how much the whole thing would weight, I'll try to have it as light as possible, but have to assume it will be a few pounds..

I was thinking to open the door when the motion sensor is triggered and close after 5 seconds or something like that.
For how long to run the motor, I was going to hardcode it based on experimentation.
 
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Bluejets

Oct 5, 2014
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Up to you.
A 12V motor on the same loading requires less current so switching elements can, for the most part, be smaller specs.
Gearbox motor essential.
As I said before, no need for a micro and no need to control length of time for the motor run.
In my experience, a 2 year old would find it difficult to decipher what is going on and be bored in a short period of time.
Maybe some brightly coloured building blocks would be a better choice.
Kids tend to chew things and stick objects in their mouth and I could imagine a pir or battery lead not to mention getting their fingers jammed in the door.
 
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Alec_t

Jul 7, 2015
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Obviously health and safety issues are important here. Any motorised mechanism will need to be weak enough to avoid crush injuries and have no protruding/sharp portions.
 
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