Garrels.be

I finally got round to creating a very simple but effective on/off button for the dragon that I created for last CCC Conference, which was themed "Here be Dragons".

Thanks to Lucy Collin for the pattern, which I more or less followed. I added some LEDs so that the dragon can actually spit fire. And for that, I needed a button. The solution is a simple press button.

First, of course, make your dragon and put LEDs in the nose openings. The plus sides of the LEDs are connected (the longest legs), the minus sides of the LEDs are also connected. I used a soldering iron and some soldering wire to do this. Two wires (one from the plus side and one from the minus side) are running through the neck and stick out of the belly, just under one of the wings where they are more or less hidden from sight. You will need a so-called coin-cell battery for the LEDs. At the end of this page is an electric scheme.

To make the switch, apply the press button as follows:

Cut out a piece of felt fabric in matching colour, slightly larger than the coin-cell battery. Using special pliers or just fine scissors, make a hole in the middel of the fabric.

Sew the male part of the button onto the fabric, using conductive wire. (If you do not use conductive thread, you will isolate the button from the circuit.)

This is how it looks on the outside:

I leave the wires a bit too long, in case I make an error. So they are coiled up a bit so that they can be hidden under the fabric rectangle. The end that will go ono the female part of the press button has a loop that fits around the top bulge of that part.

Now take the battery, and sew it onto the the dragon using the fabric as a means to hold it in place. Leave one end open, so that the battery can be replaced when it is empty. It takes about three days of none stop blinking to empty the battery.

Now sew the looped wire onto the female part of the press button. You can do this with normal thread, as long as you make sure that the loop and the wire coming from the LEDs are well connected to each other. You could also just wrap the wire around the button, provided this does not prevent it from connecting to the male part.

In this picture, you can see the battery bulging under the fabric. Just squeezing it a bit makes it slip out of the felt "bag".

By connecting the female part of the press button to the male part, you close the circuit and the battery delivers power to the LEDs.

And we have blinken lights!

These are the LEDs used:

Notice how the positive (+) leg is slightly longer than the negative (-) one.

This is the scheme:

If your lights do not blink, try putting in the battery upside down. The LEDs are sensitive to polarity (i.e. their direction in the circuit matters).