Project Development

Week 20

Introduction

Introduction

The Wisp'o'the Wind is a lamp inspired by windmills. It automatically lights up at dark, and turns off during the day to conserve energy. It features 42 individually controllable RGB-LEDs and a phototransistor. Additionally, it has an integrated space for a stepper motor, a battery, a voltage booster and a power converter to convert the AC current generated with the stepper motor to DC current. The top of the lamp has a functional wind-mill which theoretically rotates the motor all day long, storing the energy in the battery for the lamp to use after dark. Integrating the power production is a WIP as of today, June 17th 2018.

Included is a BLE (Bluetooth Low Energy) board which can be coupled with an app to control the colors of the lamp, although the integration of this circuit is a WIP as well.

While several people have created windmills for personal use, I was unable to find many that used wind to power a lamp with automated on/off functions. Several years ago, "IKEA" created a product named "SOLVINDEN" which allegedly generated its own power through wind, but at this time it appears to run solely on solar energy, and it is difficult to find further information about the product. Years later, the German company "Noordforce" created "The First Wind Powered LED Street Lamp" for remote villages. Their lamp was larger than mine, and intended to be intended for city infrastructure, as opposed to individual consumption. Their design is closed, not available to the maker community, and appears to be discontinued. The DIY community tends to be more concerned with larger windmills meant to power a small household or cabin, as these are more efficient, but I believe that my smaller scale suits hobbyists and ordinary consumers better.

I designed the turbine, which is inspired by the turbines made by Icewind, and Icelandic company. The casing is my own design as well, and includes a slew bearing which I drew, using this tutorial as a guide. I also created the LED boards, the phototransistor board and the BLE board myself, using Neil Gershenfield's designs as inspiration and guides. I created my tinyBLE as well, and a voltage converted board for the power generation. I used McMaster-Carr screws and bolts and a Jameco stepper motor (P/N: 2245600) in my design as well.

Machines and materials used for this project.

Machines and Materials required

A Fab lab is ideal, but not required.

3D printer and laser cutter

We have an Ultimaker 2 ext, which worked very well for all my printed parts. Some of my parts may not fit in smaller printers, in which case a mold could be made for casting them instead. I used PLA filament for all my parts because they are more environmentally friendly, but ABS will be more durable for long-term use outdoors.

For the laser parts we have an Epilog Mini 35 watts, which I used to cut acrylic sheets into the pieces required. These pieces would fit in a smaller laser cutter as well, as long as it is strong wnough to cut acrylics.

I used Fusion 360 and Inkscape for all my designs, and recommend it to those who wish to edit the files.

Roland Modela MDX-20 and Eagle

I used Eagle to draw all my circuits, and milled them on our Modela using a 1/64" milling bit for traces and a 1/32" bit for outlines and holes. Having the tools for riveting and soldering is essential to have a good board. You can solder wire through the vias as well, but they will not work as well as rivets in my experience. To edit these designs, you will need a program compatible with Eagle. For mass production, some rework may be required as the boards are delicate as they are.

FabISP and Arduino

I used my FabISP to program every single one of my circuits, but an AVRISP or similar should work just as well. I used the Arduino IDE to write and edit my code. I included an FTDI header on the tinyBLE board, but not on the others, opting instead to very carefully connect the rx and tx pins ont the ftdi cable to the tx and rx pins on my bus pins when communication was required beween the LED or phototransistor boards and my computer. I used CoolTerm serial monitor to facilitate such interaction.

Fitting together

My boards are securely and neatly packaged in my design, using tabs and slots in my 3D printed and laser cut parts, as well as screws to hold the layers together. One part slots onto and locks in place around the stepper motor, and there is space inside the main body for additional circuitry, which would be fastened using laser cut parts with press-fit construction, attached to one of the existing layers.

Fusion 360 was an integral part of this process, as one can import Eagle designs to ensure a perfect fit. I highly recommend this feature to others who are designing items with PCB parts.

Files

How to make a Wisp o'the Wind

Step by step, do this at home!

Phototransistor board

Mill this board as usual, traces first, then interior. Instead of soldering the phototransistor to its place, solder colored wires that connect the pads to the phototransistor. This way, the board can be placed securely within the shell, and the sensor can be placed in a place where it can better detect the ambient level of light.

milling files Eagle files Board layout

RGB boards

This is a double sided PCB, so it is a bit more complicated. Mill the RGB boards starting with the front traces, followed by the interior file. You may want to run this twice to make sure the holes are fully milled. Then flip it over, carefully centering your board in the hole, then mill the traces on the back. Remember to use rivets in all the holes. Solder all the components according to the board layout. To draw this, I had to use all the skills I learned during Output week and more. It was a challenging board to draw, but very satisfying.

milling files Eagle files board layout My own rivetting guide

Power Circuit

This circuit is meant to be used with a 12V power supply and allows you to power your board via conventional electrical outlets. Mill it as normal, then connect it carefully to the bus. This board only uses two of the pins on the bus, since it is analog, and has no need or means to communicate. For the same reasons it naturally has no code component.

Milling files Board layout Eagle files

Programming

First, download the Arduino IDE and set up the attiny 44 and 45 libraries. Then grab your favourite ISP and plug it into each board in sequence, burning the bootloader for ATtiny 44 onto the RGB boards, and the bootloader for ATtiny45 onto the phototransistor board. In both cases, they should be set to internal 8 mhz. Then push the relevant code to each board. Make sure that you have the correct microcontroller picked when pushing.

If you need help or reminding how to use the Arduino IDE or how to get the required libraries, the high-low tech guide from MIT is incredibly useful.

If you wish to change the color, do so at this step, substituting "blue" with either "red" or "green".

ArduinoRGB codephototransistor codeHigh-low tech guide

Network the circuitry

It may be a good idea to connect your pieces to a computer to monitor that the code is working as intended for each individual board. I used Coolterm to communicate with my boards, but you can use any serial monitor you like. Remember to set the baud rate to 9600, or you will only receive gibberish. To test the RGB boards, send o and O and observe if the board responds. To test the Phototransistor board, connect it, then place the sensor in a well lit area. Move your hand over the sensor to briefly give it shade, and check if it sends o's and O's depending on light level shifts.

The bus consists of a 12V pin, a ground pin, and rx pin and a tx pin. Each ground pin is marked with a "G" or a small line sticking out of it, to help you remember which way to turn the bus cable. I recommend picking one color to be the "ground" color, and sticking to this rule religiously, as it is no fun to resolder the components you ruin if you're too tired or too stressed to pay proper attention. Be very careful to orient your headers correctly when plugging your boards to the bus! A 90 degree twist will pop the regulator and 180 degrees will burn out your microcontroller. since

To get coolterm, click the button, scroll down and download the appropriate version for your computer.

Coolterm

Laser cut components

Laser the outer ring from 3mm clear acrylic sheet. The outer decorative piece and the inner splat may be cut from any color you like, but also need to be made of 3mm acrylic sheets. These schematics were designed in Fusion 360, exported as dxf, imported to Inkscape, where they were saved as svg and pdf files. pdf for cutting, svg in case someone would like to add or alter parts of the design. The decorative outer ring currently has a warding rune of safe travels on it, based on an Icelandic rune from the middle ages.

PDF filesInkscape filesDXF files

3D printed components

If you want your lamp to function outside, use PLA, and print the parts slowly, with high accuracy. If you want the lamp to be more of a short-term curiosity or you want to change colors every now and then, use PLA or other more environmentally friendly options. The blades on the turbine are designed to only just fit in their slots on the core, so use a rubber mallet to hammer them into place. The core could potentially also be turned on a HAAS digital lathe, allowing for a much more strong and durable component.

You need 12 rollers, and they look particularly great if you print six in one color and six in another, although this is solely for your own benefit, as they will not be visible when it is fully assembled. There are two models in Fusion 360. One which was my primary document, and another which I used to more accurately design the base layer and circuitry integration. Please note that in order to open the F3Z document, you must first open fusion 360 with a new design, then select upload, and find the f3z file. It is saved int his format because there are imported features (the circuit boards).

Fusion 360 filesSTL files

Base and internal Assembly

Put three screws upward through the outer ring and the lower piece. Place the RGB boards in their slots, pressing gently down until they are firmly fixed. Lower the splat down on top, so that the RGB boards are held in place, and the screws go through their respective holes. Put washers and nuts on your bolts. I used plastic washers but I am sure any of the right size will do. I used 3mm socket head cap screws. last, turn it over and place the decorative inner ring carefully in its slot, then fasten the whole thing with the center plug. This will slot up and over the bottom corners of your stepper motor with a twist.

External casing assembly

Begin by assembling the bearing. Carefully place the rollers as shown on my 3D printing page, and screw the inner races together from the inside, using four screws. You may need to drill the holes a bit bigger, depending on the accuracy of your printer.

Place the spacer on top of the stepper motor, to ensure that the screws in the bearing do not scrape along the top of your motor. Now put your motor in, aligning the bearing with the middle rod of the motor. You may need to gently tap it with a hammer to make it fit. Next, screw the corners of the motor to the outer bearing/shell. Again, you may need to make the holes larger to make them properly align. I used 3mm screws for all these parts. The small ones were 12mm long and the longer ones were 22mm long.

Turbine assembly

With a rubber mallet, hammer the blades of the turbine into their slots on the core. Then slot the core into the inner races of the bearing on the casing and twist into place.

Congratulations

You now have a wind mill themed lamp that can be plugged to a wall socket. In order to upgrade it, I need to finish programming and configuring the tinyBLE so that it enables a user to use the app to decide the color of the lamp, and I need to make a voltage booster and power converter to enable the turbine to generate the required energy. The files here are for those purposes but are WIP files and not ready for use. I included the app as well, in case anyone would like to edit or reuse it.

TinyBLE Voltage Booster by Carl AC to DC converter

Discussion

The first deadline for the project was the 11th of June, but the last day I can work on it will be the 30th of June, since my local instructor has banned me from working on personal project in his lab unless I let him tell me when and how to help out, as opposed to respecting me as an adult maker with enthusiasm and experience who helps out when and how I can. Therefore work will continue sporadically whenever I can make it to the Reykjavik Fablab. A soft deadline for improvements is the Fab14 conference in Toulouse, where I would like to display a functioning and upgraded prototype.

I have completed the outer structure of the Wisp, as well as the core electrical components. I have built and almost programmed the TinyBLE board which would interface with the app I created to allow the user to change the color of the Wisp at the touch of their phone screen. I have drawn and milled the power converter board which would take power from the stepper motor and convert in into AC to be stored on the battery, I still need to solder and integrate this board. The voltage booster board I borrowed from Carl had to be returned, and so I need to mill, solder and integrate a new one. Improving the shell is mostly done, with a small window for the phototransistor and a moulded and cast shield for it. I have drawn up a stand for the lamp, but haven't made it yet, due to time constraints. I may never be able to add all the parts that I would like to add.

The most important parts are the ble interfacing and the power conversion, but these are also the most difficult. If I am to complete them, it will either have to be before the 30th of June, or it will need to be a long-distance project worked in collaboration with the Fablab in Reykjavík, in which case it will most likely be in the fall.

I am very happy with the project as a whole, all the finished parts work, and all the remaining parts don't work... yet. It's all a matter of time, although how much time is still unknown. The primary questions that still remain unanswered are whether the turbine will actually ever be bale to produce enough energy to run the lamp, and whether the weather conditions here are too harsh for the design as is, or whether I need more weatherproofing. Throughout this process I have learned too many things to list in one go, but most importantly my skills at electronics have vastly improved, along with my programming skills. I feel like a great deal of fear has been overcome, and if I get the chance, I feel confident that I can continue expanding my skills on my own.

Conclusion

This project showed me that I have the power to create solutions which improve my surroundings. I presented it on the 13th of June 2018, and it was declared a good final project by Neil. I closed one loop, but have another two or three good loops more that I would like to close in the future. Certainly, I made mistakes in my design, like forgetting to account for the wires that come out of the stepper motor. I want to create a more dynamic design with smaller individual pieces. For example, the bearing should probably be printed seperately, the shell made thinner and slightly larger. There should be a hole for the phototransistor which is filled with a molded and cast lense through which the phototransistor can assess the light level without being exposed to the elements.

I hope to continue developing this project, at least so that I can use it myself, since it is something I've been thinking of for years, and something I truly believe would be useful once it is what it is meant to be, which is a garden light which generates it's own electricity and can stand outside in weather and wind all days of the year to light our path.

Finally, I would like to thank Bas Withagen for his support and guidance. I would like to thank Fab Lab Vestmannaeyjar and Fab Lab Reykjavík for the use of their facilities. I would also like to thank my co-students Bára Víðarsdóttir and Bergþóra Björgvinsdóttir, and special thanks to Carl-Michael Danger Conquilla, whose spirit and experience inspired my project design to new heights and whose electrical know-how probably saved the day more than once. Finally, thanks to Frosti Gíslason for being my local evaluator and Xavi Domingues for being my global evaluator.

More than anything, I want to thank my husband and my son for believing in me, encouraging me and being patient with me as I worked my way through these assignments and the documentation. I could never have done this without their love and devotion.

Fab Academy