ATtiny Hacks: Look Ma, no batteries!

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[Gadre] built his own ATtiny project without using any batteries. It’s an electronic Dice (or die if you’re being critical) which uses induction to charge a storage capacitor to act as the power source. The voltage generator is made from a tube of Perspex which houses a set of rare-earth magnets. At the enter of the tube [Gadre] machined a channel wich accepts about 1500 windings of 30 AWG magnet wire. When someone shakes the tube back and forth the magnet passes the wire, inducing a current.  The product is stored in a 4700 uF capacitor, which feeds a boost converter to power the rest of the circuit.

The ATtiny13V that controls the circuit is running its internal RC oscillator at 128 kHz, the lowest setting possible in order to minimize power consumption. After a good shake the user can press a button to roll the die, which is then displayed for several seconds on a group of seven LEDs. See for yourself in the video after the break.


  1. Pup says:

    I’d love to see a smaller, more elegant d20 version of this. :)

  2. Roboman2444 says:

    I think a bare bones kind if dead bug design with a smaller supercapacitor (those 3 volt 1f ones should do the trick) would have made it a little smaller. Perhaps even using a peizo for something that you “roll” would also be cool.

  3. Chuckt says:

    What need could this be used for?

  4. Will says:

    My god… the music… and the mic!

  5. blue skies says:

    Ok, just an observation, but don’t ya think should be TWO dice? :D
    Awesome job though.

  6. Drewbagd says:

    Fantastic man, great job! Simple and effective.

  7. Mike says:

    save vs poison!

  8. Chuckt says:

    Better get your patent before Apple files for a zero power PSU patent.,13393.html

  9. EFH says:

    This is really great work.

  10. AdV says:

    It’s very rube goldberg… Microcontrollers, capacitors, machined tubes and magnets all to ‘randomly’ give a number between 1 and 6. Or, you could use a regular old school dice :)

  11. ederosia says:

    Don’t listen to people who say “it could be smaller” or whatever. This was an exploration, not a production piece. It was fantastic. I really like how the traditional “shake it up” motion for rolling dice was integrated into the object. Nice work!

  12. cdilla says:

    That is just such a great idea. It mimicks what we already do when preparing to roll a dice. Genius.

  13. Lee says:

    Would it be possible to incorporate the Tiny with this setup?!/ Same concept, but it only illuminates one LED. Probably would need a bigger cap?

  14. Renee says:

    I kind of want to watch True Lies now.

    I also like that the act of shaking dice before a roll has been preserved, very nice!

  15. Mike says:

    Pretty neat setup.

    I wonder though, how its lifespan is affected by the moving parts. I’ve gone through a couple linear induction flesh flashlights.

    If I were asked to make a shake activated, battery-less, die, I’d tear apart a $4 solar calculator and add a tilt sensor.

  16. Sam says:

    Is it possible to kiss or blow on the device to influence the outcome to be more favorable to the user?

    If not, I’ll have to stick with the real deal.

  17. zuul says:

    good idea, bad video lol

  18. ruso says:

    Great job!

    I wonder how the ‘Por una cabeza’ argentinean tango from Carlos Cardel, got to new delhi to be the music track of this video. ¿?

  19. zrzzz says:

    Oh, that is nice! There’s got to be some way to harness more random motion like from walking or driving.

    Did you see this attiny45 robot hack over on embedded projects? Just when you thought it was tiny enough already, they have surface mount ones too!

  20. TomF says:

    @ Mike Szczys: You might want to tag this as ATtiny hack.

    Very neat idea!

  21. Andrew says:

    Why press a button to roll the dice? Detect the incoming voltage fluctuations and roll automatically.

  22. Steve says:

    I might be looking into this wrong, and while the sound could be better (neat build though) I HAVE to know what song that is. It’s driving me up the walls.

  23. Steve says:

    Figured it out (after just clicking through, doh) it’s “Por Una Cabeza”

  24. Segphalt says:

    This is also featured in “Tiny avr projects for the evil genius” also written by the author.

  25. Galane says:

    Here’s an idea for digidice for your next round of roleplaying geekery. Look up how the SGI Lavarand system was built.

    Basically it pointed a crappy webcam at several lava lamps then periodically sampled a frame of video to use as a seed to run through some random number generation algorithms. Since the seed data was completely chaotic the whole system functioned as a true random number generator with absolutely unpredictable output.

    Instead of lava lamps, the camera could be aimed at any source of visual chaos, like a room full of RPG playing geeks and nerds. ;) For more chaos, add a microphone for additional random seed data.

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