Tape Measure Generator


[Dr. West] wanted to do his small part to help save the planet. He has built a small generator from a stepper motor and a tape measure. The tape part of the tape measure was replaced with some cord. The spring loading mechanism makes the string re-wind automatically, which is nice. He shows it attached to one leg, with the string tied to the other, generating power while he walks.  This is cumbersome, but seems fairly effective. You can see him waking around in a video after the break. Would this benefit from a flywheel or friction drive to keep the motor spinning after each pull?  How can he rig it to feed off of the motion of only one leg to avoid tripping hazards?

[thanks afroman]

39 thoughts on “Tape Measure Generator

  1. That’s pretty cool. I could see someone attaching these to your arms too. Not like it is there, but like, between your shoulder and wrist. You could then wind it up like doing bicep curls. And then for storage, just put a ring on the elbow so that it would stay still, and allow the free movement of your arm.

  2. yeah attach one to each rear pocket, string to the ankle. You would get much less travel but this could be compensated by using some gears. if you put a guide loop mid thigh and mid calf you cound prolly move quite comfortably.

  3. Jobmate brand eh. Must be Canadian!

    That’s Canadian Tires store brand. Very nice idea using a step motor as generator…. As other said, using a LDO diode would be better.

    And maybe a DC-DC converter can be use to stablize the voltage as well.

  4. You aren’t really saving energy, you are still expending extra calories in order to do this. Hence more food consumed, hence more energy expended on growing food, etc. It’s still pretty cool however :-)

  5. It is a really cool idea, I honestly would have never thought to use a stepper motor.

    I’m picturing having this rigged up to doors and stuff so that when people walk in they will produce a little jolt of power.

    And just now I got another idea! The forced air heater came on in my office, so with a mini-windmill type of thing and some good bearings, you could put it in front of the heat vent and get some power whenever your furnace or a/c comes on.

  6. would be cool retrofitted to be put on one of those knee braces with the gears on them like this pic “http://renz.co.za/catalog/images/PODMX_08028.jpg” or somehow use a series of pulleys up to his knee then to hip and back down to allow the bending of the knee to pull and release tension of the cord.

  7. @trev

    Energy can neither be produced nor consumed, only converted between different forms (heat, light, sound, vibration, electricity, etc, etc,…). This is a fairly basic high school chemistry/physics topic. You can never “save” energy, you only save certain forms of energy by utilizing forms of energy that have less environmental impact. You’re not truly “conserving” energy at all!

  8. trev, you may not end up eating more. perhaps by expending those extra calories you could become thinner or stronger…

    basic human-powered generators have been around for a while – they don’t create energy out of thin air, but they do make use of what people do anyway, thus providing a little extra exercise and producing a little extra electricity.

  9. Just put it on the Cat’s back and tie the string to a back paw… or maybe route it up to a front one… you figure out how… Then roll up a news paper and whack your leg with it! Then watch that cat do all the work for you;) Better yet, how bout a Donkey… I’ve heard they’re pretty good for getting some work done…

    Or… how about an Electrostatic Generator???





  10. This could be something built into the underside of a hiking rucksack maybe. A cord going to the heel each foot, driving two generators to charge a central battery which, it turn, would provide power for for cellphone, GPS, flashlights etc. Attaching at rear of foot and legs would keep it ou the way (i think)and wouldn’t cross across legs making a trip hazard… HMMM

  11. Hey that’s a great idea dan! I’ve thought about attaching it to my hips to avoid tripping, but I never thought of wiring it into a backpack. I went with between each leg because it gives maximum power generation. The backpack would make things a lot less awkward, and give more room for a charging battery. Perhaps I’ll have to turn this into a serious project…

  12. I’m with trev on this one. The ‘energy’ comes from an increased effort in doing walking, or in other cases, open doors, drawers, etc.. The idea is interesting, but I fail to see how it is practical beyond something to go oooo at.

    In my opinion, you have to be really desperate to generate energy from walking, opening/closing drawers/doors, and other common task and be thinking much to hard. I think it is better to be more aware of your own energy consumption and make changes to that, like driving habits, electricity usage, heating of home/apartment/buildings, and so on.

  13. perhaps I should also note that this project was meant to be taken lightly. I know it is highly impractical and that there are much better energy sources out there. It is only to go oooo at.

  14. I know you meant this to be taken lightly and all, but even with the remote possibility of being useful here have you measured the power output of these generators like in a per step scenario with your ankle-to-ankle setup?

  15. Hmm… I’m not an engineer or anything, so bear with me. This video gave me a similar idea.

    You know those toy guns which, when you pull the trigger, turn some gears and make sparks inside the gun?

    Couldn’t you hack one of those guns to generate power by building a device on the bottom of your shoe (something like a spring-loaded hinge) which acted as the trigger?

    Okay, hopefully someone can interpret my idea into some technical description… this is not my subject, but the idea seems sound in my head. :)

    I think my idea would be safer than having a cord running from one leg to another.

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