turn signal biking jacket
This tutorial will show you how to build a jacket with turn signals that lets people know where you're headed when you're on your bike. Click here or on the heading above to get to the tutorial.
movement controlled RGB LED example
This tutorial will show you how to build a shirt with a flower lapel that changes color in response to movement. Click here or on the heading above to get to the tutorial.
read this before building anything
Keep your power supply and LilyPad main board as close to each other as possible in your designs. If they are too far apart, you are likely to have problems with your LilyPad resetting or just not working at all.
Why? Conductive thread has non-trivial resistance. (The 4-ply silver-coated thread from SparkFun that comes with the LilyPad starter kit has about 14 ohms/foot.) Depending on what modules you're using in your construction, your LilyPad can draw up to 50 milliamps (mA) of current, or .05 Amps. Ohm's law says that the voltage drop (the amount of voltage that you lose) across a conductive material is equal to the resistance of the conductive material times the amount of current that is flowing through it. For example, if your LilyPad is a foot away from the power supply, the total resistance of the contuctive material that attaches your LilyPad to your power supply is at least 28 ohms. (14 Ohms in the conductive thread that leads from the negative terminal of the power supply to the negative petal on the LilyPad and 14 Ohms in the conductive thread that ties the positive terminals together). This means we can expect a drop of 1.4 Volts (28 Ohms * .05 Amps) between the powersupply and LilyPad. While 5 Volts is coming out of the power supply, the LilyPad will only be getting 3.6 Volts (5 Volts - 1.4 Volts). Once the voltage at the LilyPad drops below about 3.3 Volts, it will reset.
Unfortunately, the problem is actually worse than it first appears. Silver thread gradually corrodes over time and its resistance gradually increases as it ages. You want to plan for this by keeping the resistance of these crucial power supply traces as low as possible when you first construct your design. For example, if your LilyPad is only getting 3.6 Volts initially, you're probably going to have problems in a few months.
If you are experiencing this kind of problem (if your LilyPad is resetting unexpectedly) you want to either decrease the resistance of your traces or decrease the amount of current your design is drawing. To decrease the resistance of your traces, you can stitch over existing traces with another layer of conductive thread (or, even a fine wire if you're desperate). To decrease the amount of current your design is drawing, try not to run several things at once. For example avoid powering a tri-color LED and vibrator motor at the same time if you can.