Introduction: Cat Burglar Joule Thief

Picture of Cat Burglar Joule Thief

Make a cat burglar that "steals" left over joules from used batteries. When the cat burglar gets his little paws on a battery his LED nose lights up until all the joules are gone. When drained, recycle the battery. You'll sleep more soundly knowing your batteries are completely dead.

It takes a thief to make a thief. I "stole" two Weekend Projects from Makezine and combined them into one. The Sympathy Doll and the famous Joule Thief. (BTW-Is anyone else having Weekend Project withdrawal symptoms since Bre moved to Etsy? I'm having bedwetting symptoms.)

What's a Joule Thief? A Joule Thief is a simple circuit that uses the last amount of energy (a joule) in a used battery. In essence, it's a battery drainer. It's a great little project by itself.

I'd like to give a "shout out" to others that have I've stolen from, er I mean, have inspired me.

This is a pretty easy Instructable. If you ignore family and food, you can do this in one day. "Sorry, Daddy can't help you with that broken arm; he's trying to MAKE something. Go ask Mommy to set it for you."

You can put this project together with basic tools:
Sewing machine
Embroidery Needle and Thread
Soldering iron
Heat gun or matches
Wire cutters
Sith lightsaber

Solid Core Ferrite Suppressors - Mouser - PN 875-28B0500-100 - $0.18
26 awg wire - Frys - $2.99/roll
Transistor - Mouser - PN 610-2N3904 - $0.10
White LED 10,000 mcd - Frys - $3.49
Resistor 1/4 watt - Frys - $0.95 4 Pack
Conductive Fabric "Zelt" - Less EMF
Pieces of gray and pink felt - Michaels - $0.20/sheet
Black fleece - JoAnne Fabric - $4.99/yd.
Googlee eyes - Michaels - $0.89/Pack
2 small strong magnets
Shrink tubing
Foam rubber or other stuffing
Fabric glue
Silicone glue
Box of Cap'n Crunch

I swear I put this project together before the "Get the LED Out Contest." It just happens to be great timing because I need to win that t-shirt. I'm actually writing this topless and it's really cold where I'm at. So please leave me a good rating.

Step 1: Design a Sympathy Doll

Picture of Design a Sympathy Doll

First you need to design your doll. This is where you can get creative. Design something cute or bizarre. Go crazy!

Pencil out a pattern on paper. I designed a cat burglar because they like to steal jewels.
Get it? Jewels/joules (same pronunciation)? No? Forget it.

Whatever you design, make sure it's large enough to fit all the electrical components. The photo shows the pattern with all the electronic guts laid out. Your design should also be wide enough so that the paws and arms will wrap around a biggie D size battery.

The silver "paws" are conductive fabric called "Zelt." Zelt is great stuff. I use Zelt for many of my projects. Zelt feels good against the skin. I use Zelt as a toga when I go to Tesla coil parties.

Step 2: Make the Paws

Picture of Make the Paws

From the pattern you just made, estimate the paw size and cut it out of the conductive fabric, Zelt. Then solder some pieces of wire on each. The wires should be long enough to be able to solder them up outside of the cat body (see Step 5). Reinforce this connection with a dab of silicone glue.

Next, take each of the magnets and glue them on to each of the paws. Use strong magnets but keep them apart from one another during the gluing process. You can see in the photos I got mine too close and made a mess of things.

The only magnets that I could find in my chest of trinket treasures (box of junk) were broken but they still worked fine. Also make sure the magnets are positioned so that the opposite poles are facing one another. Why? Because when your cat burglar is finished, the paws will "clasp" together. Awww cute.

At this point you may be asking yourself: "What did I just make here?" I asked the same thing after I had my third kid. Basically, what you just made are the positive and negative contacts for the battery. The magnet backing is used to stick the contacts (paws) to the metal leads of the battery. A simple solution, instead of using some kind of spring contraption.

Step 3: Sew Like a Banshee

Picture of Sew Like a Banshee

Next, cut out your pattern and pin it to a layer of fabric. Trace the pattern onto the fabric. You can use a sewing pencil or chalk. Remove the pattern.

Cut out holes for the paws. Then from the backside, sew the conductive paws you made in the previous step.

Flip the fabric to the front and create the face. First cut a very small hole for the LED nose. Using felt, create the gray mask and pink nose. The pink nose should cover the small hole you just made for the nose. Use fabric glue or sew the pieces to the fabric. Add a little smirking mouth with needle and pink thread.

Now drag out the sewing machine. Cut a small strip of gray felt to create the back of the mask.
Align it, add some fabric glue. Then place the backside fabric over everything making a kind of "fabric sandwich". Pin it all up; then you're ready to sew it up on the machine. Simply follow the pencil/chalk tracing. Do not sew the entire perimeter; leave a few inches so that you can eventually turn everything inside out. We'll call this opening the "stuffing seam."

If you're as good as me with needle and thread, you'll need to clean out your puncture wounds with Bactine before moving on to the next step.

Visit the Makezine site for more (i.e. better) information.

Step 4: MAKE the Joule Thief

Picture of MAKE the Joule Thief

Now that you've cleaned your puncture wounds you should be ready to burn yourself.

Drag out the soldering iron, wire cutters, shrink tubing, matches and the other electrical components.

First thing you need to do is the most important. Pay attention! Open up another Window on your browser and go here to find out how to make a Joule Thief.
Makezine does such a great job at explaining things. In truth, I'm just a fat, lazy slob who's tired of one finger typing.

Not funny? Well the next step is...

Step 5: Stuff It!

Picture of Stuff It!

Okay, don't be an idiot like me. Here's a "something-I'd-do-differently-if-I-was-stupid-enough-to-make-this-again" hint. Before sewing together the "fabric sandwich", you'll want to glue the LED nose in first. Duh! I failed to do this which made final assembly and stuffing it very difficult.

Saying it differently and in English - assemble your Joule Thief with all the components except the conductive paws and the LED. The paws and nose should already be attached to the fabric before turning it inside out.

Turn the doll ("fabric sandwich") inside out. You can access the wires for the paws and LED through the "stuffing seam." Solder and heat shrink these wires into the Joule Thief circuit.

Insert the Joule Thief circuit into the doll and stuff it with bits of shredded foam rubber. Instead of foam rubber you can use other non conductive stuffing material like: sock lint, hairballs or gray matter.

When you're stuffing it, make sure you don't short or break any of the wires like I did. No, I lied; I didn't break or short anything. I'm just a peon at work so I get a power rush when I nag on others.

Step 6: Finish It!

Picture of Finish It!

After sewing up the "stuffing seam" with hidden stitching, you're ready to add the details.

From scraps of black fabric sew up a tail. Just take two layers of fabric and sew up a kind of crooked tube. Cut the "tube" out and turn it inside out. Sew the tail to the body. This is important! I provided a photo to show the tail goes on the BACK.

Adding small details really help. Add whiskers with black thread. With pink thread, stitch in a "+" symbol on the positive paw. Glue on some googlee eyes. Lastly, cut small out small triangles from the pink felt and glued them to the ears.

You're done! Now go find some used batteries to drain!

I know you're probably wondering, "What can I do with my Cat Burglar Joule Thief after all my batteries are drained?" You can use it as a fridge magnet or a backpack buddy! Dudes, these are chick magnets! Take one of these to your local biker bar and hotties will be lining up! (Warning: I cannot be held responsible for any pummeling or destruction of property.)

Thanks for looking! :-)


BrunoG (author)2011-09-04

Stop stealing joules!!!!!!!!!!!!!

MadBricoleur (author)2010-05-05

Domo Kun is asking why you didn't use him instead?

anishi (author)MadBricoleur2011-04-02


harringtron (author)2008-02-01

This is great! It's useful and the steps are pretty clearly demonstrated. You've got my vote so far. I want to make one and send you my version but I don't know where to obtain Zelt. Good luck! I like that it sits on the fridge waiting, waiting...

Thanks for the vote! : -)

I bought it from a place called Less EMF.

Oh, I forgot another shout out.
Leah Buechley's site has much about textile electronics
Great info!

Yeah the fridge reminds me of the old Road Runner cartoons when the Coyote splats against a wall. : - )

the road runner cartoons were funny.

jarjar761 (author)2009-07-25

hey just for a tip u could put a video on this if u can itll realy help us on how it works

maintman712 (author)2009-04-27

Hey, there, Greetings from Florida..... Tried the joule thief, just to see if and how it'll work... talk about a surprise...I'm gonna consult with my wife, who is more crafty than I am. Thanks for the idea. K

Great! : )

brunoip (author)2009-04-02

nice work

unknownuser2007 (author)brunoip2009-05-29

Thank you! : )

amando96 (author)2009-04-01

aww it's cute lol maybe get like a chair or something for him to sit on while he eats?

unknownuser2007 (author)amando962009-05-29

Hey that's a good idea! : )

C17H19NO3 (author)2009-01-15

$5 for a huge can at Fred Meyers

masynmachien (author)2008-12-02

I continued upon your great idea and made some cute cyborg zombies feeding on “dead” batteries.

Great job! : - )

C17H19NO3 (author)2008-12-02

Get a butane iron, they heat up in 60 seconds.

eygen (author)2008-11-26

That's awesome! A cat is really suitable for this :P Also, great instructable!

unknownuser2007 (author)eygen2008-11-29

Thank you! : )

botronics (author)2008-04-06

You can add a CDS photo resistor from the transistor base to emitter and make it shut down during the day. At night, when you need the light, it will come on. I made mine into an artbot for Robogames 08. I used two series white LEDs. Current draw is about 20 to 30 ma when on at night and 1 ma when its daylight and off.

Thanks for the suggestion! I was wondering how I could add this to the circuit but I'm better at building than I am at designing. Do you recommend a particular value of CDS photo resistor? Or better yet, do you have a Digikey or Mouser part number? : - ) BTW-Great artbot!

Electronic goldmine has a nice assortment of CDS for 3 bucks.Good deal!

Just about any CDS photo resistor will work. i can look up a number for you and post it later. You can change the sensitivity by changing the value of the 1k base resistor. The larger the value, the darker it needs to be for the led to come on. Try something like 10k to 33k. If you put a 50k to 100k pot in series with the 1K, you can make it adjustable.

Thank you very much for the response! I appreciate your help! I'll try it out on my next Joule Thief project!

botronics (author)2008-04-10

My joule thief is now blinking! The battery voltage is about .6 volts. I see the voltage drops a bit when it blinks, then it will come back up and blink again. The rate started at 1 per second and has slowed down now. I started a chart of the voltage with a data logging system at work and will run it over the weekend (its still been blinking for days) till it dies. I have a movie of the blinking effect at my youtube site. The led is a resistor type, NOT a blinking led. has anyone seen this effect?

i make shooting things (author)2008-02-16

i found 15 toroid's in my old x-box!!!! as well as 2 Leds with super long leads and a bunch of transistors, and resisters (most of the leads are way to short i could solder longer ones but im lazy).

Great! I have enough parts to make four Joule Thiefs! Future Instructables. :-)

btw great instructable.

clamoring (author)2008-02-12


Thank you! : - )

WattSekunde (author)2008-02-09

Really great use of the Joule Thief! You can increase the efficiency factor dramatically by adding a small 4.7 nF (1 ... 10 nF) Capacitor parallel to the Resistor. Try with different values.

Thank you. I'll try that! : - )

jonrb (author)2008-02-02

Love it!!! Cute and functional!!!

unknownuser2007 (author)jonrb2008-02-02

Thank you! : - )

sleepydog (author)2008-02-02

What a wonderful, professionally done Instructable!!!
If you added a cadmium sulfide cell you could make the thief wait until dark to light up (two LEDs would make creepy glowing eyes). Here's a circuit that could be adapted:
I can't help wondering what other powered circuitry you could stuff inside this little guy, digital thermometer, cheap FM radio, cell phone charger (via a cord in the tail of course)...

Thanks for the idea and the link. I happen to have the same thought this morning! :- )

Chuah Lu Sheng (author)2008-02-01

u can just use a magnet to drain a battery's power.

Really? Wow. : - )

Tobi4242 (author)2008-02-01

Very creative.

unknownuser2007 (author)Tobi42422008-02-01

Thank you! : -)

guyfrom7up (author)2008-02-01

congrats on getting on make

Thanks! Yeah, that's a first for me. Flicker already had a user named "unknownuser2007" so I had to create "garagemonkeysan". : - )

MajorMercedes (author)2008-02-01

Even if it doesn't do anything REALLY useful, the fact that it's a cat that sucks the life out of your batteries is very awesomesauce. :)

Thanks! : - )

47thpageandlight (author)2008-01-29

Geek chicks and the other kinds dig these special sweet gifty-items...make it a dog or monkey instead, whatever---she'll be your love slave 4-evah!

Ha...I must agree

No doubt! : - )

mattress (author)2008-02-01

I like this concept but it's not really a very good thief. I think if there was a way to capture that last bit of energy and maybe use it to help recharge your cellphone or ipod or something that would be much better use of your thievery skills. ;)

truckmen (author)2008-01-29

It was terrible! I did exactly as instructed. I ordered all the parts and built this device. I even ate all of the Captain Crunch BEFORE I tried out the cat burglar just to be extra sure all would be fine ... but NO! As soon as I turned my back, the cat burglar and my little kitty had the most horrendous row I had ever seen. It was horrible, just horrible. My poor kitty. There is fur and battery parts strewn all over my home. :-(

deancp1 (author)truckmen2008-01-31

Jealousy - or was it love?

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