Saturday, January 5, 2013

Princess Wands

A few days ago, my daughter who is having her 5th birthday party this weekend comes up with her sweet little eyes and asks “Daddy, what special thing are we doing at my party like we did at [her brother’s].”  Of course, she was referring to the Birthday Badges that I designed and they assembled.  With less than a week until the party there certainly wasn’t time to design a PCB, have it fabbed and delivered in time without paying outrageously high costs. 

So, it was time to scramble and see what I could come up with using parts that I had on hand and could get at local stores.  Her party has a Cinderella theme.  I had a stock of blinking RGB LEDs left over from the Red Bull Fish Detector project that are a lot of fun and require only a resistor and battery to make work.  So, that sounded like a good basis for the project.  When I think of the Cinderella story, the fairy godmother and her magic come to mind.  So, the idea of a magical princess wand was born.

To build the wand, you will need a soldering iron, hot glue gun, wire cutters, box cutter or sharp knife, drill (or just good box cutter skilz) and the following components.

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QUANTITY

ITEM

COST

1

Blinking RGB LED

$0.10/each on eBay in qty of 100

1

56 Ohm 1/4W Resistor

$0.02/each on eBay in qty of 100

1

3V Coin Battery

$0.10/each on eBay.  I used CR2032’s because I had them.  Smaller ones would be better.

1

Rubber Band

Free.  Ask your mailman for some…

1

Plastic Balloon Stick

$0.20

1

Ping Pong Ball

$0.07

1

Feather or Other Decoration

$0.01

With a little planning and sourcing your parts on eBay and Amazon.com, you can build these for less than $1 per wand.  That’s a lot of magic for a buck!

You can assemble all or part of the wand before the party and have the kids do part of the assembly during the event depending on their age.  Because we had several other events planned, I chose to solder the resistors to the LEDs and drill & cut the ping pong balls prior to the event and then I quickly did the assembly of the rest of the parts during the party so they could learn how they worked.

Begin by soldering the resistor to the LED.

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Next, use a box cutter or sharp knife to split one end of the plastic balloon stick about 1.5” long.  Do not make the cut longer than the diameter of your ping pong ball.

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CAUTION: Never cut towards your fingers!  Always cut away from all body parts.  I’m not wearing that blue tape band-aid because it’s fashionable.  Even Boy Scouts need an occasional reminder… :(

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Then determine how your battery and LED need to be connected.  This is easiest by experimentation.  One wire goes on one side of the battery and the other goes on the other side.  If it doesn’t work, reverse them.  If you’ve followed my example then the longer side of the LED will go on the positive side of the battery.  Then sandwich the battery and LED into the split tube.  You should have at least 1/4” of extra tube beyond the battery when it’s all squeezed together.  If not, then split your tube some more.

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To hold all of this together, we will use the rubber band.  Begin by looping the rubber band around the top of the tube then twist the rubber band 180 degrees and folding it back over the stick and repeating three times.  Make sure this is done tightly since this is primarily what’s holding our circuit together.

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Continue the twisting and wrapping on the other side of the battery a few times and then finish by looping the rubber band back up to the top of the stick.  If you have any loose wire ends, fold them back onto their side of the battery.  IMPORTANT:  Do not let any wire contact both sides of the battery at the same time.  Really bad things can happen.

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Now drill or cut a hole in one end of your ping pong ball.  The hole should be a fairly snug fit with your balloon stick.  Also, use the box cutter to cut slits on each side of the hole slightly wider than the width of your battery.

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Next, push the stick, LED, & battery through the hole and into the ping pong ball.  Be careful not to split the ball farther.  You may have to pull the stick back out a little bit to help re-shape the ball once it’s inserted.  Push the stick all the way into the ball so that the end is firm against the opposite end of the ball and apply a liberal amount of hot glue where the stick and ball meet at the hole.  Hold this all together firm and steady while blowing the glue until it is cool and rigid.

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The final step is to cover up our cuts and hot glue with a little bling.  I had a feather laying around.  So, I added a little hot glue and wrapped the feather around the rod but you can get creative here.  Maybe some tinsel, cotton, rat tails…whatever fits the party you’re planning.  This is where the kids can participate in customizing their wand.

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Have fun and be sure to leave some comments to let me know how you improved on my design!

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1/15/2013 – W00t!  Princess Wands was featured on Hack-a-Day!

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