Requirements:

Tools:

• Soldering iron + tin
• (optional) Multimeter
• (optional) Soldering clamp
• (optional) wire stripper

Parts:

• Parallel Strip Veroboard (€ 8,22) )
• USB-A Receptacle (optional, a direct usb cable with micro or mini usb is also possible)
• 5Volt Regulator LDO (Low Dropout) LM2940 (CT) ( € 1,31)
• Heatsink for LDO (optional) (€ 0,5)
• C1             2200uF   16v (€ 0,65)
• C4             .47uF      Tantalum bead (€ 0,22)
• C5             22uF       Tantalum bead (€ 0.43)
• Bridge Rectifier, 1.5A, 100V (€ 0,5)
• Heat-shrink tubing (optional)
• ABS Case / housing (optional) (€ 1.17)
• Cable Gland Locknut (optional) or: a Grommet:
• hub dynamo connector (€ 2,- ?)

Note that these prices are ex FAT and I ordered them in larger volumes, ymmv.

Poor man’s (ms-paint) diagram

Step 1: saw a piece out of the veroboard, approximately 17 x 40 mm (the board below is too long, approx 65 in length)

Step 2: Solder the two tantalum bead capacitors on the voltage regulator. Be careful to not overheat the components, polarity is essential. Long leg is positive.
Place the 22uF Capacitor on the right,  the .47 uF on the left. Negative polarity combined in the middle.

Step 3: prepare capacitor C1 with the heat-shrink tubing, bend the pins (long leg = positive) as seen in the photo. Keep the legs as long as possible for flexible placement of this component inside the ABS case.

Step 4: place the components on the veroboard:
Looking at the first picture below; the middle three parallel stripes on the board serve as the main electrical paths for the components. The stripe on the left corresponds with the positive side on the diagram.
- C1: the long leg (+) should be placed on the left of the three middle stripes. The short leg should go in the middle. (in reference to picture 1)
Picture 1:

The bridge rectifier output legs should be placed as follows: The + (as indicated on the component) should go on the left of the three middle strips.
The – (negative) output should go in the middle. The AC input legs can be placed on the outer stripes of the board. (left and right in reference to picture 1)

And finally solder the voltage regulator as well.

Before going any further, check to see if it’s working properly.
Prepare the cable that runs to the dynamo, and connect it on the input legs of the bridge rectifier. Polarity is of course of no concern as we are dealing with an alternating current. Connect the dynamo to this kit, swing the wheel and measure the output voltage on the + (Vout) and – leg of the output regulator.

We should measure around 5 Volts

If it doesn’t work, carefully check the polarity of the capacitors and other components.

We can now safely cut the remaining component legs form the veroboard, and bend C1 to fit inside the ABS case.

I connected the heat-sink using a blind rivet this is ideal as it does not need any additional space (especially height).

Before connecting the cables, drill a small hole for the Cable Gland Locknut, connect the Cable Gland Locknut and route the wires through it.

Next, connect the USB A receptacle or if you like a mini or micro USB cable directly to the voltage regulator output legs. Connect the dynamo cable to the bridge rectifier.

In order for this whole package to fit inside the box, I had to saw one of the corners from the veroboard.

When using the same ABS case as listed in the requirements section, be sure to cut the two screw holes at the bottom of the case for more room.

That’s pretty much it. I will seal the case of with a polymer resin, to make it water proof. Be sure to only do this after you are absolutely sure everything works.

Revision 2 with grommets

That’s it! Let me know if you take on the challenge to build one yourself, or if I need to explain anything in more detail.

The latest incarnation is a stripped down version of the original. I left out the input tuning C2, C3, R1 (see original post for the diagram) and replaced the 4 Schottky diodes with an integrated bridge rectifier. The Schottky diodes  are more efficient due to the lower forward voltage drop, but require more soldering and space.  This version now fits into a small ABS case. I hope to replace the fixed USB cable with a USB A receptacle (if it fits).

I love to go on holiday by bike. And as a tech nerd I can’t be bothered by plain paper-maps!
Having a GPS-mapping application like OziExplorer on your bike makes navigation very easy.

The problem however is with the rapid draining of the battery-powered GPS / PDA.
Especially mobile phones / PDA’s have a very short (battery) lifespan, often no more then a couple of hours when the display is always on and a GPS-application running. Normally I just dragged a lot of AA aka penlite batteries with me and powered the phone with a simple battery holder like this one:

Of course this isn’t the best solution and I was looking for better alternatives.
Then I stumbled upon this genius, hub-dynamo driven “Bike mounted USB Charger” on an English bicycle forum.
The idea is quite simple. You take a HUB-Dynamo (Shimano DH-3R30) (I ordered one from ebay for less then 40 euro).
The hub-dynamo generates an alternating current that needs to be rectified and the voltage output should be regulated to 5 volts for USB powered devices.

The hub-dynamo:

These are the parts you need, available at any electronic (parts) store.
D1 – D4     1N5818
C1             2200uF   16v
C2, C3       470uF     63v   Low ESR
C4             .47uF      Tantalum bead
C5             22uF       Tantalum bead
R1             47K         .25W

Solder the parts according to this schematic:

And there you go, you have the best energy- efficient charger, all done with green energy!

This is my effort. It still needs some good housing and connectors but it works perfectly:

For more detailed information visit the bike forum at http://yacf.co.uk/forum/index.php
Many thanks go to Simon Galgut for providing the electronic schematic.