Mini LED Christmas Tree With Joule thief

Spruce up your desk this Christmas with this LED Christmas tree.  This tree is a nice
size and fairly easy to make, but best of all, it has a joule thief in it so you can squeeze
the last bit of juice out of your dead batteries and having a nice ornament to show for it.

• 30 x 3mm Green LED's
• 1 x 3mm White LED (the pattern was designed for 3mm LED's but I managed to squeeze a 5mm LED in)
• 1 x Thin sheet of ply around 150mm square.
• 1 x Emergency mobile phone charger.
• 50 - 100R resistor
• Solder

You'll need a soldering iron and some basic soldering skills.

Step 1

Print out the PDF template that's attached to step 1. Glue it down to your sheet of plywood using some light adhesive such as pritt stick or spray on adhesive.

Drill all of the holes first, I started out with a 2mm drill bit and then widened the holes to 3mm. By drilling with the 2mm bit first, you can reduce chipping of the ply by drilling from both sides with the 3mm bit.

With all of the holes drilled you can cut out around the patter with a saw (I used a jig saw, but could do this with an ordinary panel saw).

After you've cut out around the tree you can peel off the pattern. I had to use a sharp chisel to scrape the paper off my tree. Sand it all smooth and nice for the next step.

Comments

[sunshiine]

It is so cute! Thanks for sharing.
sunshiine

[BigSicilian]

Great Joule Thief (built about 20 of them) here:
http://www.instructables.com/id/Joule-Thief-LED-Night-Light/

[investman21]

Great solutions for save finances!

[canucksgirl]

Pretty and very festive. - Nice entry for the Advent Calendar. :)

[acmefixer]

I'm still looking for information about the device that is powering the LEDs. A Joule Thief is a circuit but it usually doesn't come preassembled in a cylindrical container with a jack. Also, if the LEDs are connected in series, their voltages add up. A lot of LEDs in series adds up to a lot of voltage. Fifteen green LEDs in series probably add up to over 40 volts, and that is far too high for any Joule Thief circuit.

[scraptopower]

The joule thief is ready assembled in the cylindrical container. They're sold as "emergency phone charges", usually in those £ ($) type stores.

The emergency joule thief is regulated to 5V for phone charging, There's 15 sets of 2 green leds that are in series. The green LED's are rated 2.5 - 2.8V, so it just works out nicely.

Sorry it's a bit sparse on the details at the minute, I promised it for the instructables advent calender, so published it before it had all of the details. I'll be updating it soon with a circuit diagram and more info.

[acmefixer]

Thanks for clarifying the confusion.  I'm sure future builders will appreciate the much needed info.  A few years ago Energizer came out with an emergency cell phone charger with two lithium AA cells, for something like $19 (USD), but they didn't sell.  The local Office Depot store moved them to the bargain bin for 2 dollars, and I grabbed a whole bunch.  The lithium cells alone were worth several times that much!!  I opened one up, and I have some news.  They are not Joule Thiefs.  They do use an IC chip to do the conversion.  This is most likely the case in the ones sold at the bargain/dollar stores  In my resurrected blog I am including Joule Thief flashers which would greatly extend the battery life of this project from days to weeks or months.

[Brosiman]

Nice one,but I seem to be missing the "building the Joule thief " part,also have you tested this with batteries?

[scraptopower]

It comes ready assembled with the emergency mobile phone charger. It's shown running on an AA cell in all of the pictures.