10. Make my device talk, move, etc

Note: This week’s documentation is still work in progress

This week was about learning how to deploy different output devices, such as motors, LED, sound, etc.

An output device is any piece of computer hardware that converts data or information from a computer into a form that a human can perceive, such as visual (text, images, videos), audio, or tactile output. - Wikipedia

This week was packed with a lot of learnings, which is an optimistic way of saying I made many mistakes. I didn’t manage to get a working system within the week; the board I made was barely functional, and my motors didn’t move properly.
The biggest takeaway from this week was to set realistic learning objectives considering the amount of time I have.

A lot of the work for this week was completed in the following weeks, and I have documented them under “Take 2”.

This week’s assignments (Mar 25 - Mar 31):
Group assignment:
- Measure the power consumption of output device(s).

Individual assignment:
- Add an output device to a microcontroller board I’ve designed and program it to do something.

Groupwork: Measure power consumption of output devices

In this week’s assignment, we learnt about the working voltage and curent of different devices. Understanding this enables us to prepare the right power that supplies the required current for our devices to function properly.

We also received a very useful session on Basics of electricity from the FabLab Kamakura guru, Yamamoto-san.

Link to Group Documentation

My learnings:
- xx
- xx

Add output devices to my board (Take 1)

My hope for this week was to experiment with different motor options in order to narrow down on the device that can signal the location of different spices in an effective and power-efficient way.
However unfortunately this week ended with a dysfunctional board because of several different reasons; a combination of too little time (only 2 days), not following the correct workflow for actuating motors, etc.

1. Planning

For my spice rack, I wanted to play with the idea of spices making animated motions to signal the location.

Because I would be deploying a large number of whatever devices I choose, I needed it to be relatively low power and also small. I decided to try 2 ideas that my instructors suggested; the vibration motor and electromagnetic coils.

2. Understanding my devices

Because there were no vibration motors in the lab’s inventory, I decided to go have a look in Tokyo’s electric town, Akihabara.

I bought 4 vibration motors to compare, and connected them to the Regulated power supply to test that they work, and to figure out the power requirements (working voltage and current).
Motors typically require more current, and it’s important to understand the specific power requirements of each devices first, and design a circuit that supplies the right power.

These were the readings I got:

Motor	円盤形 ブラシレス振動モーター (Disk-shaped brushless vibration motor)	リニア振動アクチュエーター (Linear Oscillatory Actuator)	円筒形 振動モーター (Cylindrical vibration motor)	Mini vibration motor 2.0mm (Seeed)
Image
Price	50 JPY	80 JPY	60 JPY	180 JPY
Site	Link	Link	Link	Link
Working Voltage	2V (1.8-4.5V)	3~6V	2V	3V (2.5-3.5V)
Working Current	50mA		70mA	80mA

3. Testing the circuit

The other approach I wanted to explore was sending electricity through copper wire coils to create an electromagnetic field around it. This would potentially be a more cost-effective way of achieving my goals.

First, Nagano-san showed me how to make a simple circuit for the electromagnetic copper wires.
Then by referring to Nagano san’s Fabricademy Documentation, I breadboarded a circuit for this simple coil electromagnet, using MOS-FET and battery power source.


It worked at the 9V that Nagano san tried. I also measured the resistance, which was xx , in order to figure out the current, which was xx. In hindsight, I should have tested the coil at a lot wider range to identify the specific voltage at which the coil functions.
I didn’t really understand why we needed a MOS-FET, but I learnt later that it is because of the very high current that the coil produces (It requires very high voltage, but its resistance is very small).

Yamamoto san also showed me a little flag contraption that I would love to try implement.


He also taught me that ideally we wrap the wires around an iron or steel rod to significantly increase the strength of the magnetic field. (Because magnetic energy attempts to take a specific path, flowing from the center of a coil, out one end, down the sides and then reversing that path. If a iron or steel core, called a solenoid, is shaped to fit this path, it will then direct the flow of magnetism through it.)

4. Designing and fabricating my board

I decided to make a board to compare my vibration motors, and also to deploy my electromagnetic coil.
The idea was to make a board on which I can prototype and compare different motors with different power. But as I learnt later, this was not a good idea, as we should only move onto designing a board after testing it thoroughly and understanding the specific requirements.

As some of my motors required 2V, which is lower than the 3V supplied by my Xiao. So I used a Voltage Divider, however I later learnt that Voltage Dividers are not a smart way of regulating Voltage when paired with Motors, as XXXX
I also soldered wires onto my vibration motors, being mindful of direction of current

5. Testing the board

Unfortunately, I had made quite a few mistakes with my board, that it was not really functional.

Before designing my custom PCB board, I should have tested the circuit with capacitor/diode and motor, and I should have tested the copper wire electromagnet first and figure out the optimum voltage and coil first.

I had such a limited time that I became too focused on finishing the board, and

Add output device to my board (Take 2)

I found the vibration of motors too weak
Considering the large number of motions I will have to make, 80 JPY per device feels a little too expensive for the little benefit they bring.
Based on this learning, an s

1. Testing vibration motors

There are severals ways to supply the required voltage, and when we are supplying to Motors, Regulators or MOS-FETS are typically recommended.

3-Terminal Regulators
An component that outputs a constant voltage. It constantly checks whether the voltage it supplies deviates from the target voltage, and if it does, adjusts it so that the voltage reaches the target value. Any excess voltage greater than the target voltage is released as heat.

Switching Regulators
While 3-Terminal Regulators only supply voltage that’s lower than input Voltage, A switching regulator can amplify the voltage.

MOS-FET
- 電子工作の素、549.0 5123 p79,

3-terminal voltage regulators and MOSFETs, while both electronic components, serve distinct functions: regulators stabilize voltage, while MOSFETs act as switches or amplifiers, with the former using the latter as a key component in some designs.

Using PWM - 電子工作パーフェクトガイド　Page 148

2. Connecting Neo-pixels

3. Understanding Electromagnetic coils

Useful links:

Files:

• OutputdeviceBoard_Layout.kicad_pcb
  
• OutputdeviceBoard_Schematic.kicad_sch

Reflections:

This week I learnt to…
- Demonstrate workflows used in controlling an output device(s) with MCU board I have designed.

Looking back, I was over-ambitious at the planning stage, and I tried to cram too many things which led to me skipping some critical steps to finish in time.
Sometimes we can’t deploy all our ideas for the final project in one week, so we need to start with scoping out realistic learning objectives for the week

Assignment Checklist:

• [ ] Linked to the group assignment page
• [ ] Documented how I determined power consumption of an output device with my group
• [ ] Documented what I learned from interfacing output device(s) to microcontroller and controlling the device(s)
• [ ] Linked to the board I made in a previous assignment, or documented my design and fabrication process if I made a new board
• [ ] Explained the programming process/es I used
• [ ] Explained any problems I encountered and how I fixed them
• [ ] Included original source code and any new design files
• [ ] Included a ‘hero shot’ of my board

Flip-disc display elements (close up). The disc rotates on the shaft that is carried in the two triangular posts. The magnet that powers the rotation can be seen embedded in the disc. Under the disc is the driving solenoid; when powered, a field is induced into the two posts, flipping the discs. Rotation stops when the disc hits the post. https://en.wikipedia.org/wiki/Flip-disc_display

https://hackaday.com/2023/03/03/a-close-look-at-how-flip-dot-displays-really-work/

Solenoids are a specially engineered electromagnet in which a coil of wire is wrapped around a specially shaped core made of steel or iron, it is an integral component in all sizes of motors.

Solenoids work like this: when electrical current goes through the loop of wire, a magnetic field accumulates around it. A iron or steel path for this force to flow into significantly increases the strength of the magnetic field. Because magnetic energy attempts to take a specific path, flowing from the center of a coil, out one end, down the sides and then reversing that path. If a iron or steel core, called a solenoid, is shaped to fit this path, it will then direct the flow of magnetism through it.

https://gigazine.net/news/20240627-flipdisk-display/ https://flipdisc.io/

https://fab.cba.mit.edu/classes/863.23/Harvard/people/Dunya/final_project/idea1/

https://www.youtube.com/watch?v=oryYiSg3wlI