Human-Powered Light--from My Book, "Doable Renewables"




About: I am an author and a maker. My current project is Santa's Shop. I'm working on a science fiction type book--more later. @EngineerRigsby
For far too many people, an untapped energy source is close and personal: body fat. Exercise is a good way to get rid of that fat (or just to stay healthy) and we might as well use that exercise for some good purpose, like lighting a room.
This project takes human activity (winding a hand-cranked generator) and stores the energy in a futuristic way (ultracapacitors) to power a very efficient LED light. The human-powered generator is costly--perhaps your school can purchase one for the science lab.

Materials and Tools

Acrylic sheet, 12 x 12 inches, 1/2 inch thick (, Part # 1005001212)
Acrylic sheet, 12 x 12 inches, 1/4 inch thick (, Part # 1002050100)
4 solid acrylic rods, 1 1/2 inch diameter, 2 inches long (, Part # 5007524100)
6 medium screws
On/off switch (, Part # 22200)
Voltmeter (, Part # 2095040)
Human-powered generator ( Part # 454213)
Cable clamp
13 screws, 1/8 inch diameter, 3/8 inch long
12 ultracapacitors ( Part # BCAP0350-E250)
Wire (#22 stranded)
Fuseholder (, Part # 108792)
Acrylic tube, 1 inch outer diameter, 12 inches long (,
Part # 6013012100)
Halogen desk lamp (, Grandrick 20-watt Halogen Desk Lamp)
Wire cutters
2 wire connectors (, Part # 302666)
Wire nut
LED light (

Step 1: Step 1

Start by attaching four 2 inch long (1 1/2 inch diameter) rods to the 12 inch square, 1/2 inch thick acrylic sheet. Predrill holes in the base and the rods, but first practice using a piece of scrap wood. �Find a hole size that will just allow a medium-sized screw to slide in and out, then reduce that diameter by 1/16 inch. �If the predrilled holes are too small, the acrylic will crack when the screws are added. �Attach the base to the rods by inserting screws into the predrilled holes.

Step 2:

Drill holes in the upper plate, a 12 inch square, 1/4 inch thick acrylic sheet, as shown on the template below.

Step 3:

Insert the on/off switch and secure it with the mounting nut as shown.

Step 4:

Insert the voltmeter and secure it with its nut.  Do not overtighten, as this can damage the meter.

Step 5:

Drill a 7/64 inch hole in the lower base, 1/4 inch from the edge and centered 6 inches from either end.  Secure the generator cable to the base with a cable clamp fastened with a 3/8 inch long by 1/8 inch diameter metal screw.

Step 6:

Using a screw (and a drilled pilot hole) fasten one of the ultracapacitors to the base, on the left side.  The ultracapacitor has its own mounting bracket. Placement of the ultracapacitors is primarily a function of personal taste.  I suggest placing the twelve ultracapacitors on the lower acrylic base (six on the left and six on the right) and--when you are satisfied with the look--lightly mark the proposed locations using a Sharpie pen.

Step 7:

Attach five more ultracapacitors to the base. Drill a 7/64 inch hole in the lower base at each capacitor location.  Using a 3/8 inch long by 1/8 inch diameter metal screw, insert the screw throught the mounting tab on the ultracapacitor.  As you mount each ultracapacitor, connect a wire from the top (positive) of each capacitor to the bottom (negative) of the next capacitor.

Step 8:

Fasten six more ultracapacitors to the right side of the base.  Again, connect positive on each of these capacitors to negative on the next capacitor in the series.

Step 9:

Attach the two final wires from the negative terminals (one on the left group, rear; one on the right group, rear) to the black wire from the generator cable.  Fasten this combination to the lower base.

Step 10:

Attach a wire to the unused positive terminal on the left group and connect it to the unused positive terminal on the right group.  Attach one end of a fuseholder to this terminal also.  Attach the other end of the fuseholder to the positive wire (white) from the generator. Fasten this attachment point to the base with a screw.

Step 11:

Drill a 3/8 inch diameter hole in a 12 inch long piece of 1 inch acrylic tubing, 1/2 inch from the end.

Step 12:

Obtain a halogen desk lamp and locate the screws that secure the protective glass shield.

Step 13:

Remove these screws.

Step 14:

Remove the halogen lamp.

Step 15:

Return the screws to their holes.  These screws hold the reflector in place.

Step 16:

Remove the bottom base cover from the desk lamp.

Step 17:

Cut wires and remove parts, leaving as much of the white wire (coming from the lamp head) as possible.

Step 18:

Grip the lamp neck with a set of pliers and twist the metal neck until it separates from the plastic base.

Step 19:

Carefully drill a 1/8 inch hole in each side of the lamp's neck--do not damage the insulation on the wires.

Step 20:

Pull the wires through the side holes.  This is done so that the tubing will fit flush against the base and not crush the wires.

Step 21:

Insert the lamp's neck into the acrylic tube.  The wires should be near the side.

Step 22:

Insert the acrylic tube assembly through the large hole in the upper acrylic plate.

Step 23:

Pull the wires from the lamp's neck through the side hole in the acrylic tube.

Step 24:

Take one wire from the lamp and crimp it into a connector with the black voltmeter lead. Attach this connector to the negative generator wire (left terminal on the base).

Step 25:

Take one wire from the on/off switch and crimp it into a connector with the red lead from the voltmeter. Attach this connector to the positive generator wire (right terminal on the base).

Step 26:

Take the other wire from the switch and connect it to the remaining lamp wire using a wire nut.

Step 27:

Insert the LED lamp into the lamp's head.  The LED light pins are compatible with the halogen lamp pins.

Step 28:

Connect the generator cable to the generator.

Step 29:

Crank the generator until you have 14 volts, as shown on your voltmeter.  Do not exceed 14.5 volts.  The ultracapacitors are rated for 15 volts, but they are the most costly component in this project, so it's best not to push the limit. Turn the switch on and you should have light.  The light will stay on until you reach about 9 volts, about one hour.

More to Think About

Is it practical to use a human-powered generator to run an air conditioner?
How could you use a human-powered generator to limit someone's TV time?
How much power can an average human produce?
How long would you be willing to wind a crank or sit on a bicycle and pedal?

Epilog Challenge

Finalist in the
Epilog Challenge

Humana Health Challenge

Runner Up in the
Humana Health Challenge



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    17 Discussions

    Instead of the expensive "human Powered Generator" why not MAKE one from a dc or stepper motor & a crank handle ????


    7 years ago on Step 29

    Hi, mrigsby.
    I'm jeab and respect to your idea.

    This is a great project. I like it. Two last years I try to make electric from water ,I use copper piece and silver piece dipped into glass water it make 0.8-0.9 volt. I use my little knowledge about electric make circuit in series until 12 volt. And connect with red LED. It light for about 24 hour when the time past it  low light . When I change new water I have bright light again. I changed from LED to motor electric but it not move. I thing not enough current.

    Today I saw you project I think If change from your generator to Battery from water.
    I want to know It will make a light or not? how long the light will bright? Can Battery from water push motor electric move or not?

    last I'm sory about my English.
    This is my fail project Battery from water.
    If you have more time please try to my question.
    I want to try make it.  but I not have knowledge  about electric.

    Thank you


    2 replies

    Reply 7 years ago on Step 29


    You are correct that your battery does not have enough current to run a motor.

    If you attach your battery to a rechargeable battery (a 1.2 volt cell--positive on your battery to positive on the rechargeable battery) the small current from your battery should slowly charge the rechargeable battery.

    After you have left your battery on the rechargeable for 24 hours, the rechargeable should run a small motor for some time.



    8 years ago on Introduction

    Nice, too bad I don't want to pay $560-565 to have some light... the hand generator is $550 by itself!


    8 years ago on Introduction

    How many volts is the hand-held generator? Can it be used for car amplifier capacitor of 2,000,000 micro farad?

    1 reply

    8 years ago on Introduction

    Interesting project. I would however recommend removing the first two sentences from your intro for a couple of reasons. One, it seems to imply (in my opinion) that this device is powered by body fat, when in fact chemical energy stored in ATP is being converted to mechanical energy - whether or not the replenishment of ATP will affect fat stores will depend on many factors (more likely the mass of muscles being used would increase if you used it a lot). And a second minor point is that everyone has body fat, just that some of us have more than we need (BMI).


    8 years ago on Introduction

    If the generatos is rated at 12V aprox, the capacitors at 15V, if wou connect 12 capacitors in series the voltage on each capacitor will be 1V aprox, and a divided total capacitance. For adding the capacitance (charge capacity) of the ultracapacitors they should be connecten in parallel. Am I wrong? is there another reason for getting them connected in series?

    2 replies

    Reply 8 years ago on Introduction

    The capacitors are actually rated at 2.5 volts each--that's why I have two banks of capacitors (six in series in each bank). The six in series gives me the needed 15 volt rating, the second group adds to the capacity.


    Reply 8 years ago on Introduction

    Ok, that explains it all. Nice ible, like it because doesn't use batteries...
    And the answers:

    1- No, the AC systems remove the heat generated by people form a room, if you'r exercising you'll produce more heat thus requiring more AC power...

    2- You'll get tired of watching TV by exercising...

    3- Between 1/4 and 1/2 horsepower

    4- 40 min daily, rated at ~1/4hp (200W) enough for my 40" LCD TV.


    8 years ago on Introduction

    if you add an rectivier you can turn the crank eter way and it will still work

    and if you use a stepper motor you will have more gain


    8 years ago on Introduction

    @ End questions
    1. Is it practical to use a human-powered generator to run an air conditioner?
    2. How could you use a human-powered generator to limit someone's TV time?
    3. How much power can an average human produce?
    4. How long would you be willing to wind a crank or sit on a bicycle and pedal?

    1. To cool a room: not even close. The average air conditioner's power requirements are way to high (Wattage wise).
    To cool a person: something could be done with a peltier cell but it wouldn't be very efficient.

    2. With a low consumption tv (modern small lcd for example) this is totally feasible.

    3. 100-300 Watts (top of that scale being short term peak production)

    4. Depends on the work load but if there are good shows on tv during the weekend, I could go all day long :).

    As a word of caution, a short circuit across charged ultra-capacitors will result in molten metal flying out at high speeds (and possibly a small explosion if the capacitor's current ). As such, they need to be treated with respect to avoid injury/death (they can also source 800A). With this in mind, I wouldn't have any contacts outside the protective box. I don't think it was explicitly mentioned but for example in step 10, do not use a screw longer than the acrylic is thick. That way the is no charged conductors outside of the box (e.x. the screw tips).


    8 years ago on Introduction

    A video would compliment the instructable nicely. you know, just to see it in action.


    8 years ago on Introduction

    Idea, a tv that is powered only by a bicycle. Wouldn't watch much tv, but would get good workout.

    1 reply

    It could be done, but I think it would need to be a small flat screen with LED back lighting. I mean really small unless you're lance Armstrong.