Battery Eater - a Robot Joule Thief Sculpture As Reading / Night Light




Introduction: Battery Eater - a Robot Joule Thief Sculpture As Reading / Night Light

About: Random creative stuff. Strong weakness for Upcycling, Open Source Hardware / Software and Industrial Vintage Design.

Welcome to my first Instructable,

hope you like it and my bad english isn't that much a barrier. :x

I had some parts lying around and wanting to build a little robot. Since i want to make one with a function, i searched and found the Joule-Thief Instructable from the Member "1up". I would to recommend you to look there for much more details on building the circuit.

The Joule-Thief Circuit makes it possible to squeeze every last drop of energy out of a "dead" battery. I like the Idea of still getting some hours of light from those batterys, you normaly allready had bring to the garbage.

I take the circuit and added some extra components to it, wich i had lay around in my scrap box.

Now it is possible to:

  • Switch light on and off
  • Dim the light
  • Switch between LED's

So this robot stands near my bed and his white LED eyes are bright enough to read some creepy books or comics. When its time to sleep i can switch to the blue light, wich ensures that the monsters and ghosts leave me alone. ;D

Step 1: Circuit: Parts and Tools

You don't need that much stuff and some parts are changeable with other versions. The circuit will then more or less efficiently eg. the Leds darker or brighter. Some of the parts can you take from broken devices. The Toroid Bead for example can you find in an CFL Lamp, I found mine in an old PC ATX power source.

I listed the parts, wich i used for the Body. But they are totaly depends on what you have laying around, be creative !


  • Soldering Iron
  • Helping Hand
  • Solder
  • Hot glue / superglue
  • Cutting knife

Circuit Parts:

  • 1x ON/OFF Switch
  • 1x Changeover Switch
  • 1x Toroid Bead
  • 1x BC 337 NPN Transistor
  • 1x 1K OHM Resistor
  • 2x White LED
  • 1x Colored Led
  • 1x Potentiometer
  • 1x small piece of circuit board
  • 2x about 1m (39 in) thin wire eg. painted wire (different colors makes assembling a little bit easier)

Body Parts:

  • Head and Arms from old HDD's
  • Body is an 37mm Film Can
  • The Battery Holder is from an old Sony Walkmen
  • 2 Front Wheels from an old pushable document container
  • a short piece of a tube
  • 3. Wheel from an old computer mouse

Step 2: Winding the Toroid

Take your two strands of wire, and twist the ends together. You don't have to do this, but it makes winding a little easier.
Thread the twisted end through the toroid, then take the other two ends (Not twisted together) and wind it once around the toroid. Don't twist the wires; make sure that two wires of the same color are not right next to each other.

Keep winding, making sure you wind the coils tight. It will still work if they are kind of loose, but it is better to have them tight.

Ideally, you want about 8-11 turns on your toroid. Even if you can fit more, don't put more on. Make sure the turns are spaced evenly around the toroid.

Once you wind around the whole toroid, cut off the extra wire, making sure you leave a couple of inches for soldering.

Strip some insulation off the wires, then take a wire from each side, making sure they are of the OPPOSITE COLOR. Twist them together, and then you're done with the toroid.

Step 3: Put It All Together

You only need to solder the electronic parts like descriped together, put a battery in the holder and the LED's should lit.

But the way how you exactly put the parts together, depends here on their method of construction and the selected parts for the body.

Maybe you got no circuit board, then you've got to solder them direct together, thats no problem. But You can now decide "will i put them all together in the body to hide them" or "put i them on the body to give him a wilder look".

What about if you got no battery holder ? How about using/making some fexible arms with magnets ? So you could put there batterys with different sizes.

So, at the end soldering and putting all together depends much on your imagination how the robot should look like, too.

Have Fun ! :)

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Participated in the
LED Contest

Circuits Contest 2016

Participated in the
Circuits Contest 2016

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    I really like how you were able to include so many different kinds of components. It looks awesome.


    Reply 4 years ago

    Thank you. :)