Published March 14, 2023

Non Intrusive Smart Lightswitch

This smart toggle switch can be installed on any light switch utilizing only the two existing screws for the plate.

IntermediateFull instructions provided10 hours14

Things used in this project

Hardware components

SG90 Micro-servo motor

Particle Argon

3D Printer

Hook Up Wire Kit, 22 AWG

USB-A to Micro-USB Cable

Software apps and online services

3D Printer Slicer

Creo Parametric

Hand tools and fabrication machines

Multitool, Screwdriver

Story

When in college I lived in an apartment that I had filled with smart devices. Naturally I wanted all the lights to be controlled by Alexa as it is extremely powerful and convenient. I could not connect the ceiling fan to Alexa without replacing the entire light switch with a smart alternative. Since I was renting this apartment this was not an option. This birthed the idea of a renter safe smart light switch alternative that used existing hardware.

Figure 1: Breadboard Setup

I had a Particle argon sitting around from another project and decided that this would a perfect use for it. I got the Argon and SG90 servo hooked up to breadboard and started to experiment with pins.

Figure 2: Soldering Setup

Figure 3: One Pin Connected

Figure 4: 3.3v Pin

Figure 5: Pins Soldered

Once I had solidified the pins that I would be using I got to work soldering the connections to make them permanent. The main power to the servo goes to the 3v3 pin, the ground from the servo goes to the ground pin and the data goes to the A3 pin. (any A pin will work).

Figure 6: Bottom Enclosure Printed

Figure 7: Bottom Enclosure

After laying out the components and finding a final layout I hopped into CAD to create an enclosure. The bottom half of the enclosure pictured above features two spots for threaded inserts, the hole for the switch to protrude through, standoffs for the main board, a servo enclosure and two mounting holes spaced perfectly for the screws used on the switch plate.

Figure 8: Threaded Inserts

After printing the bottom half I used a soldering iron to place the m2 threaded inserts.

Figure 9: Argon Mounted

The argon could then be slipped over the two standoffs on the bottom and bolted in the threaded inserts.

Figure 10: Argon and Servo Mounted

The cables could also be coiled underneath and the servo snapped into place.

Figure 11: Test Fit

A quick test of fitment guaranteed the placement.

Figure 12: Crank Slider

Next, I designed the crank slider mechanism that would be responsible for turning that rotational motion into linear motion. This is just a simple box that is constrained linearly with an arm that connects it to the servo.

https://photos.app.goo.gl/aUicB5ngRSwr1sTF7

The Link above is a video that shows the simple movement of the box used to flick the switch.

https://photos.app.goo.gl/1SMUegjrCFcdiUX4A

After the linkage was attached it was time to test the device which is seen in the video linked above.

Figure 13: Top Enclosure

With all the electronics connected and working it was time to print a press fit cover plate. This was not too complicated, just extruding the existing geometry in the opposite direction.

https://photos.app.goo.gl/kofsWTxTPU3prqxq9

The video above shows the device mounted to a lightswitch and working perfectly.

Figure 14: Final Product

With the cover plate on the device is complete and can be connected to the cloud through Particle's Alexa skill in the cloud.

Schematics

Code

Particle Argon Code

Servo myservo;  // create servo object to control a servo
                // a maximum of eight servo objects can be created

int pos = 0;// variable to store the servo position
int fanSwitch(String command)
{
    if(command.equals("On"))
    {
        myservo.write(22);
        return 1;
    }
    if(command.equals("Off"))
    {
        myservo.write(100);
        return 0;
    }
    else
    {
        return -1;
    }
}



void setup()
{
  myservo.attach(A3);
  Particle.function("On", fanSwitch); 
   // attaches the servo on the A3 pin to the servo object
  // Only supported on pins that have PWM
}


void loop()
{

 // for(pos = 0; pos < 180; pos += 1)  // goes from 0 degrees to 180 degrees
 // {                                  // in steps of 1 degree
  //  myservo.write(pos);              // tell servo to go to position in variable 'pos'
 //   delay(15);                       // waits 15ms for the servo to reach the position
 // }
 // for(pos = 180; pos>=1; pos-=1)     // goes from 180 degrees to 0 degrees
 // {
  //  myservo.write(pos);              // tell servo to go to position in variable 'pos'
  //  delay(15);                       // waits 15ms for the servo to reach the position
 // }
}

Credits

Casey Ahaus

1 project • 0 followers

I am a mechanical engineering student at the University of North Carolina Charlotte. This page is a way for me to showcase my many projects!

Non Intrusive Smart Lightswitch

Things used in this project

Hardware components

Software apps and online services

Hand tools and fabrication machines

Story

Custom parts and enclosures

Connecting rod for crank slider

Half of the enclosure

Other half of the enclosure

Constraining support for crank slider

Crank slider box

Schematics

Image of pin connections

Code

Particle Argon Code

Credits

Casey Ahaus

Comments

Embed the widget on your own site

Non Intrusive Smart Lightswitch

Non Intrusive Smart Lightswitch

Things used in this project

Hardware components

Software apps and online services

Hand tools and fabrication machines

Story

Custom parts and enclosures

Connecting rod for crank slider

Half of the enclosure

Other half of the enclosure

Constraining support for crank slider

Crank slider box

Schematics

Image of pin connections

Code

Particle Argon Code

Credits

Casey Ahaus

Comments

Related tags