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Author: rsc
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CapperLabs Greenhouse Controller - Blog 6 - Automatic Vent

rsc

CapperLabs Greenhouse Controller Table of Contents

Blog 1 Introduction
Blog 2 System Components
Blog 3 Intel Edison
Blog 4 Grove-y
Blog 5 Round and Round
Blog 6 Automatic Vent

Getting back to the Greenhouse project, my first sub-system to control is the window vent.

The greenhouse came with two vent actuators, one manual, and one automatic based on internal temperature.

The automatic opener works ok, but can't tell if its raining outside and the opening temperature can't be adjusted.

Here's the original assembly:

The unit operates using a cylinder containing a wax mixture that expands with increased temperature.

My goal is to replace the cylinder with a screw drive and stepping motor.

This is the screw drive I removed from some old equipment:

Modifications are needed to adapt the screw drive brass bearing holder to the lever arm:

After a few hours of cutting/grinding/pulling hair out/swearing, and a bandage or two, the screw drive is complete:

The screw nut is attached to the end of a brass pipe so I can get about 3 inches of travel to allow the actuator arms to open fully.

The pipe was used to allow the screw to close the actuator without traveling out the end of the unit.

Now all I need to do is attach the stepper motor to the screw shaft and connect it to a motor controller.

The Edison will control motor microstepping and direction.  I may need to add limit switches also, since there isn't any location feedback.

The SeedStudio motor shield doesn't work with the Edison Arduino board - probably not enough GPIO drive current.  I may use an aux Arduino to run the motor and send commands from the Edison.  Here's a short video of the Arduino controlling the stepper motor.

 

 

Anonymous
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  • Looking good so far. I'm looking forward to seeing the final item installed. I have a small greenhouse and it needs something like this.

     

    Dubbie

  • in reply to dubbie

    It's been so hot this summer I've left the window and door open on the greenhouse all day all month and had to put a tarp on the roof to keep the sun out.

    Scott

  • in reply to rsc

    With my greenhouse, I had to make blinds from old curtains to hang over all the windows that the sun hits, otherwiswe, even with both windows and the door open, the mercury was hitting 35 C and my temperature monitor was bombarding me with emails. I had to do firmware update to switch off the temperature alarm! Plus, in the first heatwave, it wasn't doing seedings any good!

     

    I have automatic vents similar to yours and they are slow to open. I would like to control their operation from my temperature monitor. I hadn't thought of using a leadscrew the way you have suggested. Thanks for sharing that.

     

    Neil

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  • in reply to rsc

    With my greenhouse, I had to make blinds from old curtains to hang over all the windows that the sun hits, otherwiswe, even with both windows and the door open, the mercury was hitting 35 C and my temperature monitor was bombarding me with emails. I had to do firmware update to switch off the temperature alarm! Plus, in the first heatwave, it wasn't doing seedings any good!

     

    I have automatic vents similar to yours and they are slow to open. I would like to control their operation from my temperature monitor. I hadn't thought of using a leadscrew the way you have suggested. Thanks for sharing that.

     

    Neil

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