Anto,
You can check out photos of my setup in Danneaux's Nomad gallery or Danneaux's Sherpa gallery, but mine is just is one of many configurations that will work. I actually have several different setups on various bikes and they all work fine for my needs.
At its most simple, the basic setup works like this:
//==========headlight=====taillight
Dynohub
\\==========charging unit===buffer battery===gadget
When nothing is being charged, you can choose to have your headlight switched on...or off.
When something is being charged, it is best to turn your headlight off so your gadget can receive the maximum charge.
I have found I can charge some gadgets while my light is operating, but not others. It depends on how much juice is required. Best to turn off the lights when charging. Otherwise, charging will take longer or may not happen at all.
To hook it up, the easiest way is to use piggyback connectors at the hub. The two light wires plug into the first set of connectors, and the two taillight wires plug into the headlight. The two charger wires plug into the second set of piggyback connectors at the hub. It doesn't matter which goes where.
If you are simply charging batteries rather than powering a gadget, you probably don't need a buffer battery. If you need to keep your gadget operating while going slowly or stopped, then the buffer battery will keep it from turning off at those times (and you won't have to remember to turn it back on each time you restart).
Another reason to use a buffer battery is it can allow you to charge a gadget that would otherwise draw too much power to charge directly. Charge the buffer battery, then either use it to "pass through" electricity to power your gadget or...charge the buffer battery and use it later (perhaps while in camp) to charge your device. Next day, your cycling will recharge the buffer battery and off you go again.
This is a very simple explanation, but the diagram above covers all the basics.
The hookup is easy; the difficult part is determining if a specific charging setup will indeed charge or directly power your device. Output and requirements differ, so it can take some fussing to get a setup that will reliably charge a given gadget. This can be where some research, careful selection, and even trial and error come into play.
As for hardware, it is also pretty straightforward:
• A complete pre-built front wheel with a dynohub /or/ dynohub, rim, and spokes...just like you would with a standard front wheel. Only the hub differs.
• Headlight
• Taillight (optional, you can use a battery-powered LED blinky)
• Charging unit
• Two-conductor wire
• Some crimp-on spade connectors in the proper size.
• Some piggyback spade connectors for the hub connection.
• Some way to secure the loose wires to the bike (cable ties, tape, heat-shrink tubing, etc).
• Buffer battery (optional depending on requirements).
• USB charging cord appropriate to your gadget (shorter is better).
Hope this helps.
All the best,
Dan.