# Witchy Candles

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### Witchy Candles

This computational craft project brings a little magic to your home. Touch to the rim of this bowl and the candles light up! To do this, we'll hack some LED candles to work with an Arduino and a capacitative sensor. Basic skills with Arduino and soldering are recommended.

You'll need:

3 : LED flickering candle lights

Container or large bowl

Styrofoam

Sand or gravel

Arduino ( I used a Gemma but it's easier to use an Arduino board with serial readability )

USB to Arduino cable

Wire stripper/snips

Needle

Conductive copper tape

A bit of solid core wire

1 : 1 megaohm resistor

Lithium-poly battery

Soldering iron

Solder

Hot glue gun and hot glue

Bonus:

Assorted crystals, rocks or bones for decoration

### Teacher Notes

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## Step 1: Candle Work

1. Remove the coin cell batteries from your LED candles. Once you have removed the battery cover and battery, assess whether there are holes you can sew through . If not, consider taking a Dremel to the base to make two, one near each LED lead.
2. Pry open your LED candles.
3. Check out their insides. Using a battery, and or some deduction, determine which lead is positive and which is negative.
4. Remember which is which. You'll need this for the next step.

## Step 2: Make a Base for Your Build

1. Grab a piece of styrofoam. Use your candles to figure out the size you'll cut out.
2. Cut it down to size with a sharp tool.
3. Place the candles bases down on the foam. Consider where the positive and negative leads. Orient the candle bases so that you have a clear path to connect the leads without short circuiting the circuit by sewing across leads.
4. Use a few dabs of hot glue to hold the candle bases in place.

3. Choose the right board and USB port

## Step 4: Sew and Solder the Circuit

1. The LEDs will be in a parallel circuit. See the drawing above.
2. Using your conductive thread, tie a knot to the positive lead of your first LED. Sew down and run the thread on the underside of the foam to the next LED. Sew back to the topside and connect that LED's positive leg. Go back down to the underside and repeat with the last LED.
3. Repeat this process with the negative path, being careful no to cross your two threads, which would cause a short circuit.
4. Use a bit of solder to firm the points of contact between each LED leg and its conductive thread connection.
5. Next, twist one end of your 1 megaohm resistor into a circle. This is where your rim material will connect.
6. Solder the capacitative sensor circuit. This goes from one pin to the resistor, and then to the next pin. (yellow wire pictured above)
7. Solder the ground wire to the ground leg of your the first LED in your circuit. Solder the positive leg to that LED's positive leg.
8. Now apply power and test out your circuit. Does it work? Awesome. Now it's time to assemble.

## Step 5: Assemble

1. Cut the conductive tape in one long thin strip.
2. Leave an ample tail trailing into the container but unattached. This will connect to your capacitative resistor.
3. Apply the tape to the rim of your bowl or container of choice taking care not to break the tape.
4. Place the circuit setup your container and attach the tape tail to your resistor.
6. Fill in the edges around your circuit setup with sand or gravel.
7. Add a sprinkling of crystals, rocks, bones, whatever suits your fancy, to the top of the container.

Plug it in! You're done!

V Magical.

Participated in the
Halloween Decor Contest 2016

Participated in the
Circuits Contest 2016

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## 2 Discussions

Voted!! I really love this project idea! =)

Nicely done! This is a great little project, thank you for sharing :)