25 September 2005, 22:32 by mark hoekstra

How-to hand crank power your ipod...

(...or :How I learned to stop looking for a wall socket and start cranking…)

UPDATE december 5th, 2005, I can now charge my ipod with my bicycle as well! :-)

the hand crank used

first of all, this is the magic flashlight, here in Holland it’s sold as perfectmate dynamo flashlight, but I’m sure this is one of those products which all of a sudden are all over this planet…

it comes with this socket for charging a mobile phone or something else… (btw my phone takes 6V instead of 4.2…)

it gives a rather splendid light by the way…

...with it’s 5 leds…

of course I had to open it to see what’s actually inside this thing.

other parts used

I bought a USB-extension-cable (simply because they are cheap and that way I only had to solder one side … )

...and later on, I bought these parts for making a voltage-regulation-circuit…

I gathered all this information from the topics at hackaday.com:

how-to: ‘usb battery’
how-to: ‘usb battery’ v2

the testing

so, this was my laboratory for the weekend…

I tried all kinds of different setups, here for instance, it’s a zener-diode of 5.1v + 100 ohm resistor and a diode (to make sure the current doesn’t flow the other way around (that is, from the ipod to the flashlight))...

...and it all seemed promising, but my ipod remained dead…

..so in a last desperate attempt, I removed all the voltage-regulation-logic, so only a diode, for making sure the current goes the right way, remained…

courtesy hardwarebook.net

and here’s the pin-out for a USB-plug…

...this setup gave a cool 5.8V, significantly higher than the 5V USB-power normally is, but like I said, this was becoming one last attempt… I must say I gambled a little here… according to ipodlinux.org there should be a Linear Technology LT4055 USB power controller/Li-ion linear charger inside my 1G ipod mini and even though I couldn’t find specs of it, I gambled that it could take 5.8V instead of 5V …so my choice was between getting it to work or frying my ipod…

(make sure to read my update at the bottom, after this I made yet another cable)

time to put it all to a final test (this has taken almost all of my weekend, so it’s about time!)

the final test

Well, this ipod looks empty…

...this is the last screen you see before it goes totally dead…

time to start cranking!

...this is the first sign of life you see (this is not an animated icon, but a static one)... once in a while it tries to boot the ipod (with the apple-logo showing) but in the beginning it kept falling back to this icon… so I had to crank some more!

woohoo! it gathered enough power to boot my ipod!

(this happened after appr. 30 minutes of cranking and several attempts of my ipod to boot in between but not succeeding in that)

...then it seemed it found it’s way, cause I could stop cranking and it kept charging (there are batteries in the flashlight, so those are discharging)... it kept charging for appr. 5 minutes and then this animated charge-icon became static (which I guess tells me it doesn’t charge anymore)... time to check up…

YAY! not one, but two (2!!!) stripes on the battery-icon (and two numb hands of cranking…)

well, I’m a little sarcastic here, and I didn’t test it but I guess this is something like 30? minutes of music? ...which isn’t even that bad imho


To be honest, I did go wrong on the amount of cranking I thought would be involved… On the flashlight-packaging it says 1 minute of cranking gives you 30 minutes of light, but I didn’t think it through how little current 5 leds take… so… it can very well be that the cables I made earlier, with a zener-diode to make sure I wasn’t going over 5.1 volt (check the hackaday-topic I mentioned earlier if you want to know about that), would also work but at that moment I thought I did something wrong. Well, this setup works (yay!), but with a lot of cranking involved, so I have to be quite desperate for some tunes and miles away from another possibility to charge it, before I crank power my ipod this way… but hey, it is possible! (and for me, that was the point of doing all this)

usable or not… this is going into my bag for sure and I can always use the flashlight to make my ipod sock look a little scarier...


This setup worked for me, but I really can not tell you or guarantee you this will work for you also… you are risking your ipod with this!!!


Somehow, the 5.8V this setup was giving, bothered me and kept me from putting this project away as being finished… so I continued a little until I would be satisfied with it…

So, I came up with this… a 5.1V zenerdiode to make sure the current wouldn’t go over it, a resistor to make sure it doesn’t short-cut and a diode to make sure the current flows the right way (all from the how-to: ‘usb battery’ v2)

Please tell me it’s a work of art… :-)

Aaah, this looks good…

Wow, it still looks good after I jammed this circuit inside the enclosure of the plug (a fresh one, I didn’t want any tape on this I-do-it-one-more-time-cable)

And yes!!! we have a charge-icon on the ipod!

...a little closer…

So, this wraps it up… now I have a nice cable, which also quite safely could be used on anything that uses USB-power besides this ipod… so… what shall we hand crank power today? (oh, and be my guest doing that…) :-)

DIY trackback


  1. Unangst @ 28 September 2005, 23:45 :

    This is a great setup… I have a similar crank LED flashlight which hasn’t impressed me all that much… I have always wondered about being able to hook this up to power something via usb… my only question is “How can we be sure that our projects (such as this) are wired correctly and aren’t going to permanently damage our equipment?” I suppose other than running the ideas past an electrical engineer… we are going to be taking some risk with most of these hacks.

  2. Abe @ 28 September 2005, 23:49 :

    I understand that it’s a lot of work to hand crank, what about an alternate source of cranking? Do you have a bicycle? What if you replaced the crank with a gear, and used the pedaling of the bicycle to turn the generator? Just a thought. Good work, btw, it looks like you’re having fun, and that’s the most important part.

  3. Barnes @ 29 September 2005, 01:08 :

    Thats nice. I would have never have thought to do that. Have you tried it on any other USB charged gadgets? (ie: cameras, PSP) Great idea.

  4. Joel @ 29 September 2005, 02:29 :

    You say you need an electrical engineer? Well you’ve got one. So if you have some ideas you want to run past me, feel free.

    As for the project, I like it. I don’t like your regulator circuit though. It has some potential problems and lots of room for improvement. From a mechanical perspective, you’re wasting massive amounts of energy just cranking that thing. But I think you stumbled upon a really creative solution to that already. That is to use a much faster/higher voltage storage element on the crank side. The iPod internally is going to regulate the rate at which the Li-Ion cells charge. So you railing on that crank continuously isn’t doing you any good. Any extra energy you generate more than the rate at which the iPod is charging is simply going to be wasted as heat (hopefully) in your linear regulator. Practically, you’re probably just destorying the batteries inside the generator thingamajiggy you’ve got there. So charge up a high(er) voltage storage element before the regulator, perhaps even the existing batteries if they’re suitable. The important addition here is some sort of indicator to let you know when the voltage across the secondary storage element has dropped below a certain threshold and you need to start cranking again. Maybe use a simple op-amp comparitor driving a little LED. That would be pretty easy to make. I dunno… ideas.

    I would however very much like to see the voltage at the input and output of that regulator as the iPod is charging. That’s a pretty important piece of information that you’re currently missing. Anyway, good project! Have fun!

    P.S. Those USB battery things from Hackaday are complete and utter trash. You shouldn’t be taking any pointers from those things.

  5. paul @ 29 September 2005, 09:30 :

    The iPod wall charger outputs 12v, so if you can manage it, you can double the output of the crank, although, I have no idea how.

  6. Nick @ 29 September 2005, 10:11 :

    #4, you’re wrong. The energy from cranking the flashlight is stored in the flashlights batteries. After that, because of the potential difference between the flashlight and the iPod, current flows to the iPod, charging it. Energy is wasted as heat, but no more than if he were just cranking the flishlight by itself. I don’t know if you’ve ever examined devices like this before, but they generally have a long, spring-loaded coil which is compressed by the cranking action. After this, the tension in the coil is released over a peiod of time. This is why the device continued charing for five minutes after he stopped cranking, and why cranking faster is not going to “waste” energy.

  7. sandor @ 29 September 2005, 10:15 :

    Ok my basic electronics are a little rusty, but you should be able to combine 2 ideas here with a third and be ok.

    If you make a small transformer inbetween the generator and the ipod, and then a rechargeable battery sequince set up to twelve volts after that you should get better results.

    I dont remember the specifics on the number of turns you need to step up power, but I remember the experiment from shcool and its a direct relationship. So in effect you crank the generator; the power goes to the transformer. Which steps it up to 12 volts (or whatever is safe for the battries to charge at). Then the power goes to the batteries, which in turn recharge the ipod safely and with little effort.

    All this could be put into a little box and you wind up with very little wasted energy.

  8. mark @ 29 September 2005, 10:59 :

    Well, the more recent ipods can be charged through firewire and/or USB. A firewire wall charger puts out 12V and a USB wall charger puts out 5V. The voltage-regulation/charger-circuit inside the ipod can handle both voltages. I somehow before hand already chose to do this project based on USB and 5V, but there’s no reason anyone else could base another project on firewire/12V. I’m too less of an electrical engineer to be able to overlook if and/or how 12V would be more efficient than 5V, but if anyone can provide details of that, please do.

  9. wolff000 @ 29 September 2005, 16:42 :

    to #4-Joel the usb batteries on hackaday work great. I use one and I have made several for none techy friends and no complaints, problems, or fried devices. which in my book means they work. back to the topic at hand this thing is awsome and as an avid biker I immediately so the possibilty that #2-Abe pointed out. I think I’m goin to get a couple of hand crank flashlights and go to work. Great hack and it looks good too. I love it, keep up the good work. By the way you should throw on a disclaimer so if someone screws up and fries there ipod or themselves you don’t get blamed. Remember to always cover yourself with stuff like this, unfortunately there are a lot of sue happy people out there.

  10. Kevin @ 29 September 2005, 18:23 :

    #7, while that maybe true for AC (Alternating Current) it does not hold for DC (Direct Current). Transformers are essentially two inductors linked by a magnetic field. A current inthe primary windings creats a changing magnetic field, which in turn induces an alternating current in the secondary windings proportional to the number of turns. If you had four (4) turns on the primary side and eight (8) on the secondary you would double (2X) your voltage and half (.5X) your current following your conservation of power (P=I*V). A perfect transformer would have zero (0) loss, that is, there would be perfect conservation of power. However due to the mechanics of the cores utilized in transformers, some of the power is dissipated as heat in the transformer and thus useful power is not conserved.
    ... Sorry, didn’t mean to lecture. Great project, should be more useful with the HDD-less Nano.

  11. Joel @ 29 September 2005, 19:17 :

    #6, you don’t understand. If you are cranking something by hand, you are expending energy. Period. You are doing mechanical work, regardless of whether it’s being converted to electrical energy or not. If he wasn’t doing work, he wouldn’t be complaining about being tired and having a sore hand afterwards. If this device does use a spring loaded coil then that would change things a bit, but the result is still pretty much the same. Instead of beating on the internal batteries, overcranking is serving to wear out whatever clutch mechanism is in place so that you may not over-extend the spring. Again, any additional cranking is lost as heat and does no useful work. And again, the iPod’s charging rate remains independant of any cranking done so any cranking done in excess of the minimum is pointless and only serves to tire yourself out (because you’re expending energy that’s being wasted).

    #7, you can’t exactly use a transformer in this application with any ease. You could potentially chop up the DC with an oscillator and then drive a transformer, but that’s not very practical. It would make much more sense to construct a simple voltage doubler circuit. Very few componants and very high efficiency. Although, I wouldn’t recommend it. It’s not really necessary.

    #9, I’m not debating whether or not the USB batteries work, I’m just saying they’re not good. I mean, you can pound a nail into a piece of wood with your forehead, but it’s not exactly the best course of action if there was hammering to be done. The first design is simply aweful. The second is better, but still bad. With one or two more componants it would be possible to increase the efficiency nearly two fold, greatly extending life of the battery. Basically, they’re just terribly wasteful. The best out of the two (second one) dumps about 40% of the energy stored in that little 9v battery as heat. That’s terrible. Something like that would never make it to production.

  12. Jeff @ 29 September 2005, 23:13 :

    I just completed this project for myself with a power input of 5.5 instead of 5.8 and it took about 45 minutes to crank my ipod to half :) Thinking of rigging a electrical engine to the crank but thats a whole other project. Well done!!!

    Jeff – http://jeffeh.com

  13. Klaus @ 30 September 2005, 01:21 :

    Im not sure about the 1G mini, but the 2G mini is rated for 5-30V with a max xurrent of 1A, so the extra few volts you had in your earlier design should be fine. What about hocking it up to a dynamo on a bick using an AC to DC converter (or 4 diodes)?

  14. Damien Elbo @ 30 September 2005, 03:03 :

    I’ve heard that if you buy a charger and plug the charger into the ac outlet of your house and put your iPod in the charger you can also charge your iPod that way. Just FYI.

  15. reboots @ 30 September 2005, 23:53 :

    The datasheet for the LT4055 is available from the Linear Technology website at http://www.linear.com. Here’s a direct link: http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1037,C1078,C1088,P2436,D1518

    The absolute maximum rated input is 6VDC.

  16. MARAWAN @ 1 October 2005, 04:47 :


  17. Tom R @ 1 October 2005, 05:07 :

    Nice way to get big arms :) + to charge up your ipod. I hope to see more of those “modding” idea done since they are GREAT!

  18. JCB @ 1 October 2005, 07:02 :


  19. Smarter Than You @ 1 October 2005, 19:33 :

    What an incredible waste of time!!!

  20. TJ @ 2 October 2005, 22:11 :

    Nice thing you made. Greetings from the farm.

  21. olliestyles @ 3 October 2005, 13:45 :

    hey kudos to you for having a crack at life bro, inventiveness got us to where we are today.

    #11 joel i am interested to hear of your improvements to the design of the usb batteries to improve their efficiency. fyi i have zero electronics knowledge – i just like fooling around and that stuff looks like a nice basic project for a cat like me. but naturally i’d like to do it better…

  22. beev @ 5 October 2005, 01:04 :

    Have you ever seen the old ‘dynamo’ system for powering the lights on your bicycle? If you could adapt one of them so people could charge their phones and iPods as they cycle, I’m sure you would have a markatable product.

    Similarly, a device that harnesses the power from an exercise bike would be incredibly useful.

  23. david @ 14 October 2005, 03:29 :

    You can buy a voltage regulator IC just about anywhere you can buy a zener diode. Go get a LM2937ET-5.0

    Match that with a pair of capacitors (>10uf to ground on output and .1uf on input) and you’ve got a reliable regulator that has built in protection from switched poles, short circuit, and overheating.

  24. mark @ 14 October 2005, 13:10 :

    Well… I’ve been looking into more intelligent ways of voltage-regulation than this zenerdiode but found that to be realiable, I need more than the current 6 volts that comes out of the hand-crank. So that’s why I chose the zenerdiode…

    BTW, there are some nice ideas in this thread and there’s a second handcrank coming my way, so expect some more projects based on these ingredients :-)

  25. Richard @ 15 October 2005, 11:50 :

    very nice. But one improvement would be to ditch the whole linear regulators(both zener diodes or regulators), and use a high efficiency DC-DC converter. Linear regulators can waste 50% or more energy just lowering the voltage while the dc-dc(switching regulator) can waste as litle as 5%.
    something like this

    Also making sure the battery in the “magic flashlight” that holds the charge to charge the ipod is big enough so you can stop cranking and wait while it charges.
    (but be sure to use the correct type, for instance a lithum-ion battery will burst into flames if overcharged)

  26. Gerhard @ 26 October 2005, 13:20 :

    Great and nice Project,

    if possible test that little sweet thing with an I-Pod Nano, if that works fine, i will build it by myself.

    One more thing, i´ve a PowerToGo für my Palm,is it possible to build an connector to take this Powerdevice as charge unit ? Any Ideas ?


  27. Mason @ 13 November 2005, 08:50 :

    Sweet. I want to make one of those. Can you give me a detailed description on what was on the mother board of the dynamo flashlight U used to power your ipod? Untill I buy that flashlight.
    I like that it has variable output

  28. Doug @ 17 November 2005, 22:31 :

    What about a pump that generate power (rather than a crank)? Isn’t there something about how electricty flows that would make a pump a more simple device? And would it be easier to handle a pump as opposed to a crank (set it against something solid, anchor it with your foot, and start the ‘ol in and out)? Does anyone know of this sort of thing. What I really want is to be able to charge up a 12v batt that can in turn be used to recharge a laptop.

  29. matt @ 27 November 2005, 23:43 :

    Good Job Mark! Keep doing stuff just because you can. To everyone else, he may not have done it the best way, but he did it his way. If you don’t like his version, make your own guide for everyone to use. If you can make a better version, why haven’t you?

  30. Mark @ 2 December 2005, 13:46 :

    Outstanding idea, at least from the standpoint of using your noggin. The world needs as many people as it can get who are willing to take a fresh look at things. I hope all the suggestions above are taken as constructive criticism, (even when the writer’s intent seems oriented in another direction!). I’m impressed.

  31. Carlos Abel @ 7 December 2005, 04:01 :

    What about a battery pack using 4 AA batteries with a step-up voltage regulator? I’ve done it, and it works!

    check out my site: http://carlosabel.no.sapo.pt/

  32. Adam @ 10 January 2006, 02:09 :

    I’m awesome.

  33. Highest IQ @ 15 January 2006, 05:06 :

    Hand-cranked music. We’ve come a long way, baybe!

    (Does anyone remember this? http://www2.danbbs.dk/~erikoest/graphics/hmv.jpg)

  34. ken @ 21 January 2006, 23:26 :

    I think that the idea of the portable crank is great for emergency charging. There is an emergency radio out with a beefier hand generator and will charge cell phone and other items. I like the idea of the bicycle for non portable use. A good physical storage device for energy is a flywheel. Applications for charging obviously include cameras, computers, radios and PDA’s. The environmental damage caused by heavy metals (lead,mercury and cadmium) in batteries is significant. Emergency situations, boats at sea or isolated areas all can use alternative charging. Why not try a small solar cell for your ipod????

  35. Sam Wane @ 31 January 2006, 02:30 :

    Great invention. I found your site whilst researching my solar powered mobile ‘phone charger http://homepage.ntlworld.com/sam.wane/solarcharger/solarcharger.htm

  36. Chris @ 15 March 2006, 04:39 :

    I need some help with a similar project. I’m planning on spending a year overseas in a location with no reliable source of electricity or batteries. I want to be able to charge my ipod, phone and PDA. I picked up the solio solar charger, but there will be extended times when the sun is also not reliable (rainy season). I also picked up the sidewinder hand charger, but there are no adaptors for the ipod or my PDA. As my PDA was to serve as my source of reading material, my data collector etc. This is quite distressing to me…is there anyway I can adapt the sidwider to use either the USB cable or a female cigarette charger? Are there other solutions you recommend? I’m ignorant of basic electronics, but not too dim, and willing to learn. Any and all suggestions of how I can power my system (sun, hand etc) are very much appreciated…but there is one other catch…I have a very limited amount of baggage I can take with me so size and weight are also of critical importance.




  37. penz @ 29 March 2006, 15:17 :

    i want to make something like that too. i was thinking a hand-cranked octopus wire, so that i can plug anything to it. but i’m a newbie in the electrical stuff. would you help me? some useful sites would be wonderful.

  38. bubba @ 9 April 2006, 03:11 :

    well, sir, i think u are to crazy smart… maybe u should go outside more often…

  39. Shira @ 11 April 2006, 17:59 :

    Excellent work. I was looking for a hand crank generator for my laptop (which would have been a godsend when I lived in Istanbul), and it is wonderful to see your work. Keep it up,

  40. villy @ 11 April 2006, 23:43 :

    excellent! felicitaciones por tu trabajo y empeño por soluciones con elementos alternativos

  41. a cool guy @ 13 April 2006, 08:08 :

    you are a nerd

  42. Celery @ 19 April 2006, 04:51 :

    I made a similar cable that works for PSP, and Had an interchangable head For GBA, But when used on a Nintendo DS, It Fried it. I also got a report from a friend that it fried his PSP, litarally(It was like, charcoal). But It works for charges under 15 minutes, and Charges psp for a good hour and a half in that time. If you want my instructions, contact me at celery_etomocky@yahoo.com. Ill tell for free, and I will sell these babies for 6 bucks, it only costs 4 to make.

  43. John @ 1 May 2006, 13:36 :

    Very Cool and clever.

  44. Nik Uttam @ 8 May 2006, 04:04 :

    I hav an iriver H10 is there a way u can use the came handcrank flashlight on this type of player?

  45. Evan G. @ 16 May 2006, 01:48 :

    I have the solar charger part from an old solar outdoor lawn light. Is there any way that I can use this for my iPod becase I will be away this summer with lots of sunlight and barely any outlets.



  46. LieBtrau @ 25 May 2006, 13:15 :

    If you want a cheap circuit for a charger for your iPod Nano, have a look at: iPod charger circuit

  47. Steve @ 18 June 2006, 15:43 :

    Great Idea! I wondered about making one, but the amount of cranking discourages me. By the way #33, I love my old victrolas and I thought your comment was priceless!

  48. Laurence @ 23 June 2006, 15:07 :

    This sounded like a real good idea, but far too complex. I’m headed out to the Gambia for a 6 week solo bike trip. Currently there is no power in any of the inland places im headed; so i decided to seek out a simpler system. I have a wind up
    phone charger, with loads of different adapters. As i only need the Nokia one, i canibalised another one, to expose the red and black power cables. I then tested the max power output at full wind with a gunsons power tester. It came to 10amps, which is 57amps below the max ipod charger output for a wall charger. As such, i bought an ipod usb cable from ebay for £2, cut off the usb end, then exposed the red and black power cables from the ipod usb adapter end. Connected these with the canibalised phone adapter—and job done. Five or so turns, and the ipod starts charging.

    Simple, and effective. I admire taking the concept to the extreme, but it is quite a simple alteration; without the need for all of the safety additions that seem to have been added.

    (The phone charges at a much lower power than the ipod afterall … so if the wind up charger is safe for the phone to be charged, the ipod will be fine)


  49. mark @ 23 June 2006, 15:21 :

    >This sounded like a real good idea, but far too complex.

    Well, whatever suits you. In my case I wanted to make sure that I didn’t fry my ipod and my charger charges a batterypack from which the iPod, with some safety-features get’s charged. Personally I didn’t like the idea to charge my iPod straight from a dynamo… But, like I said, whatever suits you (best)...

    >The phone charges at a much lower power than the ipod afterall …

    Well, I wouldn’t trust the science that went into the cheap phonechargers that are all over the place right now ;-)



  50. andia loveday @ 5 October 2006, 09:42 :

    I have built a wind up charger for my science project. It will charge up this other phone but no matter how hard i tryed i couldn’t get it to charge up my dads Nokia 6015 cellphone do you have any idea why it won’t charge?

    any way would it be possible to get it to put out a stable 19 volts so it will charge a laptop?

  51. mustafa @ 8 October 2006, 09:22 :

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  52. mustafa @ 8 October 2006, 09:56 :

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  53. tak @ 15 October 2006, 02:24 :

    Awesome, I had the same idea (bought a similar, but smaller hand powered flashlight from the drugstore last week).

    If cranking the thing excessivley would just be a waste of effort…
    It would be cool to have some sort of wind up toy type system where you wind it up and it turns at a regular pace…

    just a thought

  54. amym @ 27 October 2006, 00:22 :

    i was wondering what kind of dynamo you used?

  55. bob dole @ 4 November 2006, 23:36 :

    That is awesome!!! I was thinking, could you do that to a car if you had a big enough hand crank?!

  56. Bob dole @ 4 November 2006, 23:47 :

    # 51+52, learn how to spell!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

  57. Your MOM!!!!!!!!!!! @ 8 November 2006, 21:28 :

    if your sell this item i will be your first customer! i lost my first charger and i don’t want to loose another one, cost to much!

  58. Sirdar @ 20 November 2006, 17:09 :

    Actually 55, I’ve been thinking of that exact question. “Can a dynamo crank power a car?”

    I believe I have a partial theory, and anyone here is free to expand on it.

    The basic concept of the dynamo crank isn’t new. Ben Franklin is said to have tinkered with it in his electrical experiments.

    The main problem that has always been a major stopping point for the completely electric car is power. As in, making a small amount of power create a bigger effect.

    But in theory, man does that already, with inventions like the pulley. I propose a similar, electrical version of this.

    What you do is, take two crank set-ups. The first one is going to be small, and a manual crank that you will use. Crank that one for maybe five minutes. This will power up a small battery. This battery will then power the starter and an internal crank system which generates and stores a LOT more power in a bigger battery. This will be used to charge up your car’s systems. You can also perhaps tie in solar panels for extra juice.

    Voila. In theory, a completely independantly-powered electric car, that will continue to self-generate power between cranking and solar energy. No gas needed whatsoever.

  59. EQ2 Gold @ 31 December 2006, 19:07 :

    very good.

  60. ernesto @ 29 January 2007, 01:52 :

    fuck you stone avenue

  61. ipodfan @ 30 January 2007, 18:52 :

    there is this crank up radio that has a big ass hairspring in it that you wind up and it charges a Nicad battery maybe some one could hack this thing apart and rig it to charge an ipod

  62. vincent @ 15 February 2007, 02:35 :

    awesome idea i made on myself but what i did and i think its awesome is that i took out the little battery inside of it and replaced it with the battery from a broken ipod shuffle. and you can crank it to charge the battery and it will stay charging for like an hour or two i guess or like 45 minutes. lol im not sure i never timed it but email me with any questions. vinnygx3pimp@bellsouth.net

  63. Pushkar Bhatkoti @ 11 March 2007, 02:40 :

    Great work dude.

    Pushkar Bhatkoti

  64. selena @ 6 April 2007, 08:39 :

    TO:purchasing department
    Please allow us to introduce our company, Zhejiang Wenzhou Kaishi Electric Co., Ltd. We are a manufacturer of environmentally-friendly flashlights. We are mainland China’s first manufacturer of this kind of product. We are ISO 9001-2000 certified and all of our products are patented in China, and we have received CE and ROHS certifications.

    Our dynamo flashlight/cell phone charger which works without any batteries, only cranking the handle, it will generate electricity. The generated electricity not only used for lighting, but also used for charging mobile phone.
    This is our web: www.ksl-flashlight.com

  65. Joel johnson @ 19 April 2007, 23:42 :

    send me one

  66. doug @ 24 April 2007, 22:44 :

    I just checked a car charger for an iPod Nano. It appears (from behavior; can’t open it non-destructively) to contain nothing more than a series diode. There is a LED which dims slowly after disconnect, so there must also be an internal capacitor, and I suspect there may be a transient suppressor of some sort. Unloaded output voltage is simply about 0.6V below input voltage. The implication of this is that the iPod nano has an internal switched mode charger. Actual LiIon cell voltage will be not less than about 2.5V at “full” discharge (limited by protection circuitry) and 4.2V (usually a little less; lower voltage will yield a little less capacity but longer cycle life – important in a device where the battery is permanent). It is quite probable that the Fire Wire power input to the iPod will accept any voltage from about 5V to at least 12V. There MAY be some issues with the lower end, since a switched mode converter is more or less a constant power input device, given constant output power – if the input voltage is halved, the input current will double, unless deliberately limited. Current to the LiIon cell must be limited. My guess is that the cell in the iPod nano is less than 1Ah, so max charge current would typically be around 0.5A (“C/2”). It is just about impossible to safely fully charge most small lithium ion or lithium polymer cells in less than an hour. At high charge current, the voltage reaches maximum quickly, but must remain at that level for some time to fully charge. Mistreated lithium ion cells can explode if you are mean to them.

    There are two common alternatives to switched mode charging circuits for LiIon. Where input voltage is around 5V, linear regulators are common. They will range from about 50% to 85% efficient from a 5V input, depending on state of charge. “Pulse” chargers rely on current-limited input, and essentially connect the input directly to the battery until full charge is reached, at which time they begin to control the duty cycle of the switch, eventually turning it off completely.

    I have some flashlights that use a multi-phase alternator that charges an internal coin type lithium ion cell. They aren’t very well designed, and allow the cell to overdischarge, which is damaging.

    If I wanted to charge an iPod from a flashlight that had a 6V output, and could demonstrate that that voltage was not exceeded by more than a small amount, I would put a silicon diode in series with the 6V output, shove it up the USB power path, and call it done. I would approach any of this with fear and trepidation without actually KNOWNING what is internal to the iPod.

  67. Sri Iyer @ 11 July 2007, 14:16 :


    Hey I am currently working for a non-profit organization in UGanda. The country is very poor, as I guess you all know. But one of the biggest problems is that only 5% of houses in the country have electricity.

    I need some help in developing a very cost effective but efficient hand crank flashlight to distribute to villages around this area. Just having one dependable source of light in a household will provide a huge amount of benefit to someone in Uganda (i.e. more time to work, study, safety for children, protection etc.)

    You all seem like very smart people, and I was wondering if it was possible to develop a way to use gravity to power a flashlight. As in you have a weight like a bucket that turns a pulley, to turn a dynamo, which then charges the battery in the flashlight.

    This way with one drop of the weight they could prolly get a good hour of light from the flashlight. The hand cranks available online are all way too expensive. The ideal price would have to be around 4-8 dollars for the whole set-up. If any of you have any thoughts, or can guide me to where I can find the right parts, please please let me know. Thank you

    Sri Iyer

    World Vision, Uganda


  68. Peter B. @ 18 August 2007, 23:18 :

    re: Solio charger (#36 Chris): The Solio has a jack for charging from an AC adapter that puts out 5.5V. Assuming you already invested in Solio tips/cables for your devices you could simply make a cable to connect the 6V output of the handcrank flashlight charger to the Solio input.

  69. Buckminster @ 26 August 2007, 17:46 :

    Damien Elbo @ 30 September 2005, 02:03 :

    “I’ve heard that if you buy a charger and plug the charger into the ac outlet of your house and put your iPod in the charger you can also charge your iPod that way. Just FYI.”

    I’ve heard that if you committed suicide nobody would notice. Just FYI (Forget You Idiot) (Forget Your Idea) (Fist Your Irides).

  70. Try one with this!!! @ 28 November 2007, 20:46 :

    Try using this as a dynamo to get the full 12V
    Item# 10-PM3695


  71. Swbf2guy @ 4 December 2007, 07:18 :

    LOL!! It looked like you took a long time to make it!!! LOL!!!

  72. bish @ 30 January 2008, 07:02 :

    i know he posted that message over 2yrs ago, but ive just browsed here, started reading comments, and lmfao at jeff –
    “Thinking of rigging a electrical engine to the crank but thats a whole other project.”

    if you have electrical power to run an engine to power the crank, why not just plug your ipod in with a proper ipod charger!?! surely the whole point of this hack is for charging ipods when miles away from power sources, like, camping out in a forest or something?

    bizarre. cool hack though, mark!

  73. ppang @ 15 February 2008, 21:38 :

    Check out this handcrank USB charger from compact-impact.com…opinions?


  74. Alec @ 12 April 2008, 10:05 :

    Sweet, I’m trying the charge the iPod thing using tons of dead and used batteries that still have a bit of charge left in them. I did a hugely crude test today. The iPod had the charging symbol, so I’m making progress…

  75. RIP @ 21 September 2008, 23:47 :

    RIP Mark – Hope you’re hacking your way around heaven.

  76. Iceberg @ 28 October 2008, 21:59 :

    Just a stupid question. How did you calculate the 330 ohm resistors? I get totally different numbers…

  77. Tim @ 21 August 2009, 08:40 :

    Very cool, that seems like a handy device =p

  78. home solar @ 22 October 2009, 07:26 :

    Looks Really Great, Keep it up.

  79. Me @ 26 December 2009, 17:03 :

    Passed through in a hunt for information on the iPhone power supply and Li-ion polymer charge circuitry and specs, hope to gain a  deeper understanding of  Li-ion  and Li-ion polymer (and other) renewable energy storage, specifically in iPhones and was intrigues by your descriptions of the hand cranked concept, especially how great the variable output influences overall battery longevity, healthy performance and recharge capacity, and am also interested in any data on the field performance, testing, and safety research, I have seen alot of material which failed after only 9 months,(bought brand new, the only cell phone I ever had a major problem with) which leads me to question my decision to buy a 32GB 3gs to replace my 8GB 3giphone.   

  80. Home Made Energy @ 23 January 2010, 15:27 :

    Thanks, really useful information.

  81. watches @ 28 March 2010, 07:52 :

    Downtown Bangkok, Thailand, was a government agency building bombingreplica watchesHeld around the world, “Earth Hour” event (14) (Chart)replica watchesUnrest in southern Yemen, 40 people were arrested, 28 people were injuredreplica watchesOld shell out the new book, “Love can always overcome hate one another,” accused of ballot papers to find the Torahreplica watchesSouth Korean frigate sunk 20 meters takes about 20 days of salvage

  82. christopher hurst @ 15 April 2010, 22:56 :

    my i pod wont charge on a charger

  83. raph @ 8 June 2010, 12:08 :

    if you replace the crank handle piece with a lego wheel or a skateboard wheel you could mount it on your bike’s frame round the rear wheel (make sure it goes on the rim and not the tire) and then when you take your bike out it could charge, quite rapidly and with little extra effort and without having to do an action unique to recharging a usb powered gadget!!!

  84. watchfordream @ 19 August 2010, 06:00 :

    Very cool, that seems like a handy device

  85. cheap uggs the only boot sal @ 20 August 2010, 00:17 :

    Outstanding idea, at least from the standpoint of using your noggin. The world needs as many people as it can get who are willing to take a fresh look at things. I hope all the suggestions above are taken as constructive criticism, (even when the writer’s intent seems oriented in another direction!). I’m impressed.

  86. replica @ 27 August 2010, 04:13 :


  87. battery @ 4 September 2010, 09:16 :

    The iPod had the charging symbol, so I’m making progress…

  88. dogbox @ 4 September 2010, 15:43 :

    This whole crank energy thing is amazing. Imagine if you will – hooking up a dynamo to the wheel of a bike, but instead of powering an ipod – you actually powered an LED light!!! OR even better to cut down on Carbon emissions say you cut holes in the floor of your car, took the engine out…..great idea mate – I,m only winding you up:)
    Its easy to have a laugh now in 2010 – the market is flooded with cheap and cheerfull chinese made hand crank chargers, torches, radios – etc. this was done in 2005 so your ahead of the game – cheers

  89. Eric Layne @ 27 September 2010, 18:16 :

    RIP Mark, condolences to his family & friends.

  90. discount luxury watch @ 13 October 2010, 06:33 :

    Very nice presentation .Love it much !

  91. prezzi orologi @ 19 November 2010, 12:22 :

    it contains lot of information. I always prefer to read the quality content and this thing I found in you post. Thanks for sharing.

As mentioned in the Message from Mark's family this site has been made static. This means that it will be no longer possible to comment on his ideas and projects, but that we all can continue to cherish his creativity.

             you can find all of my projects overhere