Ridiculous exerciser becomes useful as a charger

[Scott Nietfeld] built a charger from a Dyna-flex wrist exerciser. We hadn’t heard of a these gyroscopic devices before but once we saw the promo video (embedded after the break) we realized that this is the kind of thing that infomercials were made to sell. [Scott] knew the internals spun to fairly high RPM and figured that adding a few magnets on the inside and coils on the outside would turn this thing into a generator. Four rare-earth magnets fit the bill, with two external coils feeding a rectifier and linear regulator. Below you can see his demonstration video where he takes the orb apart, then spins it up, generating 250 mA at about 7.5 volts to drive the regulator and charge a cellphone. Not bad!

Dyna-flex promo video

[Scott's] walkthrough video:


  1. Karlo says:

    Available commercially since 2006:


    And the powerball is great!

  2. lee says:

    I remember my dad had one of these when I was a kid. It was a bitch to start, but worst of all it hurt like hell when you tried to stop it with your skin… #dontdothat lol

  3. Imanoss says:

    Powerball – one of the wankiest ideas i have ever seen.

    (note innuendo)

  4. Squirrel says:

    When I saw ridiculous exerciser, the first thing that came to mind was the shake weight

  5. antitroll? says:

    The power ball is not a useless device, I own one and use it every day. The results are extremely noticeable.

  6. Fallen says:

    Shake weight would get the job done. And it would give you a nice refreshing splash once the phone is charged. :P

  7. sd says:

    +1 for the Powerball. I have one on the mantelpiece right now. It passes the time when I’m waiting for the missus to get ready before we go out.

  8. Filespace says:

    @fallen You saw that south park episode about the shake weight too!…ROFLMAO

  9. svofski says:

    Powerballs are super awesome. Don’t know what’s ridiculous about them, they are great toys. I have two.

  10. colecoman1982 says:

    Entering sleep mode…

  11. Jive says:

    Powerballs are great, and you really can’t understand how it works till you have tried one. By the time you get it up to operating RPM, it takes all the muscles in your forearm to keep it going. Do it for 5 minutes, and your entire arm aches. I bought one about 5 years ago, and always wondered why someone didn’t convert one into a charger. Great write up!

  12. loki233 says:

    yeah these things are really good, the first time you try one you’ll be feeling worn out within a minute

  13. lee says:

    @loki233 that’s what she said…

  14. Piku says:

    Huh? you’ve never heard of a Powerball before?

    … and you claim to be a tech blog. Did you never read Slashdot or visit ThinkGeek when these things were popular?

    I’ve got one, it sits on the mantlepiece along with some buckyballs.

  15. Ivan says:

    Long live the powerball! How come you’ve never heard of it? This fascinating display of Newtonian physics is even for sale on thinkgeek. Geeks love gyroscopes, so do hackers :)

  16. John Laur says:

    The powerballs have a magnet inside them already and there is a little RPM counter you can snap into the top.

    They used to sell an ISA card and wired sensors that would plug into up to 4 powerballs and display the RPMs in realtime on the screen so you could have competitions. I have one somewhere; it was a lot of fun. It would be rather easy to duplicate the functionality of this system these days with a small microcontroller and a few hall effect sensors. Maybe I’ll dig it out and try it.

  17. MrX says:

    Like many I also own a powerball. I find it impressive that TFA calls it a ridiculous device. One might look ridiculous (wanker) while exercising with it, however I promise that the results are serious. I use it regularly to complement push-ups.

    One thing that this little ball can do that no other exercising device can is shaping of wrist muscles, these muscles are really difficult to exercise.

    +1 for powerball

  18. ferdi says:

    i belive this balls are original made for astonouts to train in space pepole that use the ball no how hevy it can by to train whit it
    it looks of you have havy ball off steel that will fly out off your hand do to the g force generaat by the steel ring
    nice bild

  19. James says:

    Powerballs are great and make a massive difference to wrist strength for things like badminton/tennis. But I can see why they might look like something from bidupTV.

  20. ehrichweiss says:

    I thought of the generator aspect years ago when I first got my Powerball, so this is great. That said, “ridiculous”?!?!? Seriously? Those things are awesome. You can’t even begin to describe how well they work until you’ve used one.

  21. Michael says:

    The powerball I’ve laying around even has a built-in generator, used to power a series of leds on the spinning ball that functions as a POV-display, showing your peak RPM. Using this power to charge a cellphone is quite a bit more useful of course!

  22. James says:

    I love the Dynaflex gyros! Really great for my carpal tunnel!

  23. Jehu says:

    Yeah, the Powerball Techno would be the way to go for a project like this. No need to take the ball apart to mount more magnets. I would be putting any more magnets in the rotor of one of these anyway. Too much risk of unbalancing it and at 15krpm I’d hate to be holding it if it breaks.

  24. Spork says:

    You are worrying for no reason. Even if it were to break, it has momentum in a spinning motion. The result would be like a billiards ball that spins in place, even at 15k RPM in your hand, the worst that happens is it falls out and rolls on the floor.

  25. Fallen says:

    @Spork, I think he was refering to the rotor holding the magnets breaking, not the outer shell. I’m pretty sure that if that rotor broke those magnets would fly outwards.

  26. Anon says:

    Cool idea, but a small switchmode regulator will waste much less energy than a 7805 linear.

  27. kanamycin says:


    LMAO that video is hilarious!

  28. i have this gyroball thing, i will give it a shot :)

  29. NatureTM says:

    You can’t say it better in less words. “Ridiculous exerciser becomes useful as a charger”

  30. element_leader says:

    Wouldn’t Fushigi make a better charger? It has like magic and s#it.

  31. Jehu says:

    @Fallen. Exactly. The outer shell of these things is pretty tough but the rotor is the bit I would be worried about. Even at 7krpm the rotor can bite your hand. I know, I have one. Having a few shards of Nickle plated NeFeBo flying around in there and a cracked rotor would not treat your hand very nicely.

  32. Munkeegutz says:

    I am an avid rock climber, and these things are excellent. Definitely not infomercial material!

  33. Scott says:

    @Jehu. The rotors actually have an .25″ thick aluminum sleeve in them that spans the circumference, so I think there’s very little chance of the rotor cracking all the way through. I’ve had the magnets pop out of the spokes while the thing was running, but it didn’t do much more than make a terrible rattling sound and slow the rotor to a stop.

  34. effigy says:

    @ferdi, that was a cute attempt at english

  35. Whatnot says:

    It’s odd to see ferdi’s english, normally the dutch don’t have much trouble with it.

    And it’s also odd that he doesn’t use firefox with the english dictionary for spellcheck, but that’s not that uncommon as we all know ;)

    But it’s still clear enough and it makes his posts stand out. Actually.. come to think of it – maybe it’s all some trick to get noticed, that would be sort of clever.

  36. DanAdamKOF says:

    Kinda offtpoic but I love that the background song for the Powerball video is Svenson & Gielen’s “The Beauty Of Silence”. I play that song a lot in beatmania IIDX.

  37. Ozzy_Coff says:

    So we could take this idea and use the concept of producing electricity from gyroscopic rotational devices and use it on a larger scale. Where could this idea else be used you may ask, well after watching this idea I thought this project could be scaled up and used in gymnasiums everywhere. Potentially exploitable human produced energy is wasted at gyms where people could power theses generators! Am I brilliant or what? Of course this would require new designed equipment but if mass produced this could be very positive in the search for a greener future.

  38. alex says:

    +1 for the power-ball. It is really great for developing wrist strength which is critical for rock climbing. I had a friend who broke his arm as was prescribed one of these to regain his strength.

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