One of the key aspects of this project is to be able to control wearable displays using a wearable computer. The wearable displays I am using are Electroluminescent (EL) Panels and Wire. These displays are not like regular LED’s cannot be switched on with a microcontroller quite so easily, as in this example.

It took me quite a long time to figure out how to do this, and I must thank Mikey Sklar who explained the process to me. These are more like instructions than a tutorial, and will explain to you how to set up the necessary components. So if you are interested in using EL displays in your next wearable computing project, this tutorial will explain how to switch and control them using a microcontroller.

What you will need: Firstly you will need the following:

• Microcontroller (I recommend arduino or wiring, or you can make your own)
• EL Panels or Wire (whichever you want to use, the process is the same for both)
• EL Inverter (I recommend one from coolight)
• Resistors (100 ohm)
• A breadboard to prototype on
• Triacs (I use ones from digikey, part# 497-4682-1-ND)

Steps: Perform the following in order:

PLEASE NOTE: you will firstly need to program your microcontroller with appropriate program to turn on/and off the panels using your computer. I suggest looking at my tutorial here for wirelessly switching LED’s. The principle here is the same, if you follow the intructions for setting up the EL panels, then you should be able to switch them using similar code.

1. Connect a wire from the output pin in your microcontroller to a 100ohm resistor (the output is the pin you have selected in your microcontroller program to send the on/off signal)
2. Hold your triac up in front of you so the flat side is facing you:
   - Connect the left most pin to the 100ohm resistor you just set up
   - Connect the center pin to your Earth connection
   - Connect the right most pin to a piece of wire
3. Now connect the piece of wire on the right most pin of the triac, to one terminal of your EL panel or wire. EL does not really have positive or negative so it doesnt matter which you connect to at this point.
4. Now take your inverter, which should have 4 connections. 2 of these are for battery power, the other 2 are for powering the EL. Take the negative of these 2, and connect it to the same ground connection as the middle triac pin. Take the remaining positive and connect it to the remaining terminal of your EL panel or wire.
5. Now you will need to connect the micrcontoller and inverter up to your battery power source. It is important that they share the same power source, because powering the inverter seperatley while having it connected to the microcontoller may over power and melt the battery.
6. Once everything is connected, it should look similar to this diagram below. In the diagram, the flat side of the triac is facing AWAY from you, so that the resistor is now connected to the right pin, Earth connection is still middle pin, and left pin goes to the EL.

Or you can view images of this setup here.

You can follow this process to connect as many EL panels or wire to your micrcontoller as you want, but remember, the more EL you add, the less bright they become when all switched on at the same time. For example, the diagram below shows how you would connect 3. It is basically the same pattern repeated. Once again in this diagram the flat side of the triac is pointed AWAY from you.

Or you can view images of this setup here.