Published February 28, 2020 © CC BY-NC-SA

The Mesmerizer

A project that's nice to look at, nothing more, nothing less.

BeginnerFull instructions provided15 hours918

Things used in this project

Hardware components

Raspberry Pi 4 Model B

Adafruit Servo Driver - PCA9685

MG90S digital servo

Software apps and online services

Raspberry Pi Raspbian

Hand tools and fabrication machines

3D Printer (generic)

Story

Project Video

3D Printing

1 / 4

We start off with quite some 3D printing. You can use any filament and colour you like, we chose some white and black PETG.

The first things to print are four little plates to attach to the servo's, don't worry we will go into more detail in the next step.

We also need a base plate with four holes, each little servo will click nicely into them.

Next are four side plates, completing the box construction.

Last but not least we print some decorative arrows to put on top of he servos.

All model files are included.

Assembling

1 / 3

With all that printing done, we can move on to the assembling.

First things first, we can click the servo plate on each servo, if all went well it's a snug fit.

After which we drill a hole in the bottom plate (forgot to add it to the model), and pull through the wires.

Then we can click each servo into the bottom plate, the result will be a nice looking box, with open sides.

Now for some gluing, use the servo hubs and glue an arrow on each of them, see the picture for the desired result. After the arrows are attached, you can pop the hubs on the servos.

All that's left to do is glue on the sides and the assembling step is done!

Electronics and Code

1 / 3

For the electronic side of things were are using a Raspberry Pi 4, but any Pi will do.

Because we want to control four servos we need a little help, an Adafruit Servo Driver will do nicely.

They have a great tutorial on setting up, wiring and using the chip.

With the hardware done, the code is next.

The code itself is attached, here's an overview of its workings:

Set up the servo driver and initiate the connected servos
Add each servo to our list of servos
Loop over this list and set the starting position
For eternity keep looping over the servos
Based on chance and their current position, move them either left or right.

Feel free to play with the position settings and sleep!

Result!

1 / 3

And that's it!

The standard setting gives it a slightly eerie feeling, but mesmerizing none the less!

Now if you don't mind, we have stuff to stare at....

Code

mesmiCode.py

# imports
import board
from board import SCL, SDA
import busio
import adafruit_pca9685
from adafruit_motor import servo
import time
import random

# Setup the servo driver an initiale the connected servos
i2c = busio.I2C(SCL, SDA)
pca = adafruit_pca9685.PCA9685(i2c)
pca.frequency = 50

servos = []

servo0 = servo.Servo(pca.channels[0])
servo1 = servo.Servo(pca.channels[1])
servo2 = servo.Servo(pca.channels[2])
servo3 = servo.Servo(pca.channels[3])

# Add each servo to our list of servos
servos.append(servo0)
servos.append(servo1)
servos.append(servo2)
servos.append(servo3)

# Loop over this list and set the starting position
for servo in servos:
    servo.angle = 45

# A variable to set speed of servo movements
steps = 5

while True:

    # For eternity keep looping over the servos
    for servo in servos:

        # Based on chance and their current position move either left or right.
        if random.randint(0,1) == 0:
            if servo.angle < steps:
                servo.angle += steps
            else:
                servo.angle -= steps
        else:
            if servo.angle > (180-steps):
                servo.angle -= steps
            else:
                servo.angle += steps

    time.sleep(0.15)

The Mesmerizer

Things used in this project

Hardware components

Software apps and online services

Hand tools and fabrication machines

Story

Project Video

3D Printing

Assembling

Electronics and Code

Result!

Custom parts and enclosures

Arrow

Bottom Plate

Servo Plate

Side Plate

Code

mesmiCode.py

Credits

Comments

Embed the widget on your own site

The Mesmerizer

The Mesmerizer

Things used in this project

Hardware components

Software apps and online services

Hand tools and fabrication machines

Story

Project Video

3D Printing

Assembling

Electronics and Code

Result!

Custom parts and enclosures

Arrow

Bottom Plate

Servo Plate

Side Plate

Code

mesmiCode.py

Credits

Comments

Related channels and tags