LEO is a dimmable lamp module project intended for everyone who wants to get into electronics or already is. Some workshop experience is required, you may also look up a tutorial on how to solder, if you do it for the first time.

This Instructable provides templates, the code and a circuit diagram for the main LEO unit. It's up to you if want to put it on the ceiling, build a stand, put some in series or even create a whole array. You also can modify the code, add a diffusor etc.

LEO is a project we created within 3 days during a school workshop week. Our task was to make an open-source product along with a recipe. Recipes leave room for own interpretation, so the provided instructions are the main dish, the mounting solution is the side dish, which we leave up to the builders imagination.

Thanks to our workshop professors Sigi Moeslinger and Masamichi Udagawa from Antenna Design.

project by Dimitri Leimgrübler, Nicolas Lienhard and Elio Amato

Fachhochschule Nordwestschweiz FHNW

Hochschule für Gestaltung und Kunst

Institut Industrial Design

Freilager-Platz 1

CH-4023 Basel

Step 1: Required Material

M3 threaded rod, 25cm length
M3 Bolts
20x M3 nuts, 8x M3 end nuts
1mm tinplate format A3
8x luster terminals
8x o-rings 6mm, plastic dowel 3mm
Arduino Pro Mini (5V variant) board or compatible
FTDI breakout board
1MΩ resistor
10W LED driver board
10W LED module
IRF 520 MOSFET or similar logic level MOSFET
stranded wire, red/white or black
small electical wire
12V power supply unit

The easiest way to get your electronic components is from ebay, aliexpress or similar websites.

additional tools for programming

You are going to need a computer and an FTDI breakout board for programming your microcontroller. Install Arduino from the arduino.cc website and open the provided code. Every line of code is commented. Instructions on how to programm the Pro Mini board are available on arduino.cc/en/Guide/ArduinoProMini

used tools

Some of these tools are recommendations. There is more than one way to skin a cat.

vise / bar clamp
jigsaw / band saw / coping saw
drill (4mm drill bit, 6mm drill bit)
file / sand paper / countersink
soldering iron ,solder
multimeter
double sided tape
hot glue

Step 2: Bring Your Tinplate in to Shape

Download the template pdf and print it 1:1 scale.

You can stick the template directly to your tinplate with some tape.

Drill the holes first and cut out according to the template.

Don't forget to break the sharp edges with a file.

Bend the pieces along the marked lines. I'ts easy to bend the sheet metal over an edge of a table or in a vise.

We used some scotch-brite to brush the individual pieces after bending. Another optional step is to protect your metal from corrosion. We used some clear varnish on our parts.

Use a saw to shorten the threaded rod to 5cm pieces.

leo_building_instructions.pdf
Download

Step 3: Programming and Wiring

Before we solder the circuit according to the circuit diagram, we want to write the code on to the Pro Mini module.

If you're not familiar to Arduino already, you might want to read this tutorial first: arduino.cc/en/Guide/ArduinoProMini

Download and open the leo_firmware.ino file and take a look at the code. The code is responsible for the touch and dimming action. Each line is heavily commented and should be easy to understand. If you want you can customise it and make strobe and flashing patterns for example.

Compile and upload the code to your Pro Mini.

Put your LED module in place (we used some thermal compound for enhancing cooling) and solder your components together. Start with the Pro Mini by adding the wires for the power on the RAW (positive) and GND (negative) pin. Continue by adding the 1 megaohm resistor directly in between pin 2 and 4. Add a wire on the one resistor leg at pin 2, which we connect to the touch plate later on. Add the necessary power wires to the LED driver board.

Place your components to the carrier plate. You can stick the MOSFET directly to the plate with double sided tape. The double side tape creates a good electrical insulation from the components to the metal plate. For the the Pro Mini and the LED driver board, we used some additional hot glue. Make sure no solder/bare wires etc. make contact with the metal plate.

You can now wire the individual pieces together, according to the wiring diagram.

Use a pair of luster terminals to connect all the positive and negative pair of power wires.

Use some sanding paper to roughen a small spot on in the center of the touch plate. Here you should be able to solder on the sense wire. If the plate does not get hot enough to melt the solder, you can optionally use a small bolt and nut to fix it.

Use some your thicker wire to connect the luster terminal according to the photo, so they fit trough the holes on the sensor plate. The pattern as shown in the picture allow connecting multiple LEOs in parallel.

leo_firmware.zip
Download

Step 4: Testing and Assebling Sensorplate

Before we do the final assembly, we want to make sure, we don't have any undesired electrical connections.

Set your multimeter to continuity testing mode and check following in combination to the carrier plate:

MOSFET heatsink
both LED terminals
RAW, GND, pin 11, 2 and 4 on the Pro Mini
all terminals on the LED driver module

If you are sure there are no short circuits what so ever, you can fix your wires and connection with some hot glue. This acts mainly as strain relief and makes for some more rigidity.

The sensor plate needs to be insulated from the housing completely in order to work properly. Cut a thin section from the top part of the plastic dowel. This ring will be the spacer in between the threaded rod and the sensor plate.

Add a end nut to each of the the 5cm pieces of threaded rod, an o-ring, the plastic spacer and then push them through the holes in the sensor plate. Secure the threaded rod with another o-ring and a nut.

Again it is important to check once more for an electrical connection in between the touch plate and the threaded rods. Make sure there is none.

Step 5: Final Assembly

Align the carrier plate and push the rods trough the holes.

Tighten each one with a nut an add a second counter nut. The usage of loctite or a similar product is recommended. Optionally you can use some lock nuts.

Use another 2 nuts (or a lock nut) on each rod with a 2.5mm spacing to the end of the rod. The final step is to add the housing and fix it with 4 end nuts.

Step 6: Adding a Stand & Modding

Stand

Use your own creativity to make a stand. The possibility is endless. Just make sure you don't mess up the polarity. In case you do, the Pro Mini boards usually have a protection diode and the specific led driver we use does not care about polarity on the input terminals at all. Also make sure you don't short out your power supply. We got ours from an old LCD monitor, wich is luckily protected with a self resetting fuse.

The luster terminals are meant to provide the physical and electrical connection for the stand. Their alignment is designed to allow daisy chaining and make grid like arrays.

For testing purposes we took a piece of offcut wood and some welding rods.

Mod

LEO is meant to be modded. On our second unit we extended the threaded rods and added an acrylic diffusor. We also connected wires to the luster terminals to mount it to the ceiling.

Go wild.

Have fun.

do what you want ('cause a pirate is free)