There have been a few "iPod hand-crank generators" on the web however, we've not seen one using locally-Australian sourced parts. So, we've fixed that with this Hand-Crahnk USB powergen charger. All the bits can be purchased from Jaycar Electronics stores in Australia and New Zealand. 

The iPod Shuffle is one of a number of MP3 players and other devices that require a PC USB port in order to recharge their internal Lithium-ion battery.

That’s all well and good while you’re near a PC with a USB port but imagine you’re on the island set of Lost or your the only known survivor of a nuclear holocaust. OK, maybe something more realistic – you live in Sydney and you travel to work by train.
This hack turns a $20 dynamo torch from Jaycar Electronics into a hand-powered USB power generator with enough kick to give your iPod Shuffle 25minutes of playback time with just a four-minute workout on the crankhandle.

WARNING – This hack requires you knowing which is the pointy end of a soldering iron. If that’s not you, find a mate who does. Check the parts list box for all the things you’ll need but you shouldn’t need to spend more than $30. Using this will probably void your iPod’s warranty, particularly if you don’t build it up right and the player blows up. So, do this at your own risk.

Hacking the torch

First off, take the torch and remove the four Philips head screws from the back. Keep them safe and take off the top cover.

Underneath, you’ll see the back of the motor at back and a circuit board with two wires connected to the motor. Desolder these wires and remove the three Philips head screws holding the circuit board in place.

DON’T LOSE THESE SCREWS – you’ll need them later.

Pull up the circuit board with the LEDs and the front bezel. Put the circuit board aside – you won’t need it any more but keep the bezel – we’ll use it in a moment.

Don’t pull up the black base – keep this in place or else you’ll muck up the gears underneath.

The next step is to make the circuit board. Using a small hacksaw or Stanley knife cut out a 60x32mm section of 96x75mm PC board from the pack – make sure that the copper tracks on the back are running vertically when you hold the board with its long edge on the horizontal.

Before you solder anything in, drill out the three mounting holes – you’ll need to measure these out and use a 3/16-inch drill bit for these.

Once that’s done, follow our component overlay diagram and solder the components into place.

If you’ve never soldered before, I don’t recommend you build this gizmo on your own. If you want to learn how to solder, check out my video on the website but practice first on some scraps before you start working on this circuit.

Here’s the order in which I recommend you solder the components – start with the wire links, then the diodes, the resistor, the capacitors and finally the three-terminal regulator.

Installing the USB socket 

This is a little tricky but not too difficult.

First up, take a pair of needle-nose pliers and looking directly at the front of the socket, cut the outer clamp on the right-hand side of the socket. Alternatively, you can do what I did in the photo and that's to bend it underneath itself. However, you might it a little more difficult to get the socket to sit down neatly as the clamp tends to sit up a little bit. Anyway, the choice is up to you.

Next, installed the socket pins into the correct position on the circuit-board and solder them. After that, wrap the left-hand clamp around the end of the circuit-board to help anchor the socket into place.

The circuit

This is a good time to explain what you’re building. It’s what’s called a basic voltage regulated power supply and here’s how it works.

When you crank the handle, the gears increase the rotational speed from around 2RPM to around 10,000RPM. Normally, you apply power to a DC motor to make the sfat spin, but here, the motor coil cuts through the lines of magnetic flux created by the permanent magnets inside the motor, which causes electric current to flow through the motor coil.

If you want more detail, read the HowStuffWorks guide at http://electronics.howstuffworks.com/motor1.htm.

The motor in this particular torch is a 12VDC brush motor so crank the handle fast enough and it will deliver around 12VDC at up to 300mA.

In our circuit, the motor terminals are connected to four diodes themselves connected up as what’s called a “bridge rectifier”. Normally, this turns AC power into DC power we can use but here, they have a different use.

If you crank the handle in one direction, we get a flow of electrons (making the electrical current) in one direction, but crank it the other and the electrons go the other way.

That won’t do our iPod Shuffle any good so we use the bridge rectifier to redirect the current, so that regardless of which way we turn the handle, we always get the current flowing in the direction we need.

(Electrons run from the negative termal of a DC power source to the positive terminal, but it’s often easier to follow a circuit by talking about “conventional current” flow, which is said to run from the positive to negative terminal.)

From the positive output of the bridge rectifier, the current is fed via a 100uF filtering capacitor to our three-terminal regulator chip. This chip ensures that our output voltage never varies more than 5% from 5V DC, matching the base USB specifications. We’ve used a special LM2940CT-5 low-dropout regulator here, as it only needs an input of 5.5V to ensure a smooth 5VDC output. You could use a cheaper and more common 7805, but it needs 7V DC input, which means you’ll need to crank a bit faster for it to work.

The output of the regulator goes to another filter capacitor and then onto the USB socket.

Here, pin 1 of the socket is the 5VDC rail and pin 4 is ground. You’ll need to check that you’ve got this right before connecting anything up of serious value, in case you blow it up.

We’ve also connected up a green 5mm LED to the output. Its job is to guide you to how fast you need to turn the handle. Once the LED reaches maximum brightness, you won’t need to spin the handle any faster.

And that’s pretty much how it works.

Checking the board 

Now before you install the board, check it carefully for soldering errors – in my experience, most problems with electronic projects usually involve soldering.

Here’s my best tip – connect up your digital multimeter. If you don’t have a digital multimeter, stop right now, get down to Jaycar Electronics and pick up one for $10. Got it? Good.

Set your digital multimeter to the lowest ohms (resistance) setting with the red lead in the positive (+) socket and the black lead in the negative (-)/ground socket. Preferably, the meter should have a beeper. See if yours does by just connecting the two probes together. That should get you a continuous tone from the meter.

Now connect the probes to each adjacent pair of copper tracks on the back from one end of the board to the other – and you should hear nothing. You may hear a quick little chirp when you come up to the two capacitors but that should quickly stop. You don’t want to hear any continuous tones.

If you do, check to see if you have a splash of solder connecting the two tracks. There should be no solder joining two tracks together. If so, use a solder sucker or a sharp box knife to scrap it away.

If you get through the whole board with no beeps, you’re ready to install it into the torch.

Installing the board 

Anchor the board now in place using the three Philips head screws and add two wires to the motor and the wires to the LED. Note the motor leads can be connected either way but make sure you get the LED wires right or else it won’t light up. Use the wiring diagram as your guide. I've taken a couple of liberties here by anchoring the LED leads directly to the resistor R1 - soldering them to the PC board proper would be the better way to do this. There's plenty of room to do this but it would obviously need to be done before you screw the board to the shell base.

Hacking the torch shell 

Next, now we need to make a hole for the USB socket to poke through.

Start by drilling three 3mm holes in the top shell.

Then using a small wood file, clean up the hole, using the USB socket as a guide.

Try and keep your work neat as it’s easy to scratch up the shell’s silver paint.

As you work with the file, try to keep all corners nice and neat. Try to fit the top shell back into position. 

As soon as the hole is big enough, clean up the edges with the file and then you’re ready to test it. You’ll need to angle the shell first and then straighten it up once the socket pokes through.

When using the socket, remember that it's only anchored in by those four soldered pins as well as the clamping action of the top shell coming down on the PC board. So don't be too rough with it - it should take the rigours or normal use, but don't swing it around like a cricket-bat! If you do leave that right hand clamp on the USB socket intact, you'll find the fact it sits up a bit will allow the top of the torch shell to press down more firmly, anchoring the whole thing that little bit more.

Testing

Set your digital multimeter set to 20V DC range and connect it to the test points on the wiring diagram and get someone to turn the handle for you. You should measure some voltage less than 5VDC until they get the speed up but importantly, you should measure a positive reading – if it’s negative, you’ve somehow managed to get things back to front. If so, stop look over the circuit and see where you went wrong, fix up the errors and try again.

If you get that positive voltage reading, try getting the cranking speed up to around 1.5RPM and you should measure close to +5V. If it’s more than 5.5V DC, you’ve got a problem so check over your work again.

If everything is working correctly, you’re ready for the big test – plugging in your player.

Remember, we can’t take responsibility for your blowing up your MP3 player because you haven’t built this thing properly so if you’re still a bit iffy, get someone to check your work for you.

If you’re ready for take-off, plug your iPod Shuffle into the USB socket and start cranking.

You’ll see the Shuffle’s main green LED on the front start flashing and then go out, the handle and this time will be very easy to turn. After about ten seconds, the charge LED on the back will light up and then about five seconds after that, the handle will all of a sudden become a lot heavier to turn.

If that happens, congratulations – your iPod Shuffle is now charging and you’ve hacked what I might say is a pretty cool USB hand-crank charger.

NOTES:

Of course, not only can you charge up an iPod Shuffle but any other MP3 player as well. The beauty here is that by including a USB socket in the design, you can actually use this charger with any USB device, including a mobile phone charging cable.

TIPS:

If you try to charge this with one of the full-sized iPods, you'll find that it won't charge. Having read a little around the USB specification (and although I've not tried it yet), it looks as though one solution could be to solder a 1kohm 1/4-watt resistor between the two middle pins of the USB socket (there is plenty of room for this at the top-left of the PC board). This tells the iPod that it's connected to a USB power source and it "should" start charging. (Again, there's no warranty on this hack - given or implied - so do it at your own risk.) 

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