Bill of materials
The 3 main componenets are:
1. A small electric hydrogenerator (http://www.amazon.co.uk/Portable-Micro-hydro-Generator-Charger-Efficiency/dp/B00K74GPVM/ref=sr_1_2?ie=UTF8&qid=1449326254&sr=8-2&keywords=micro+hydro+generator) £9
2. A voltage regulator to convert 12v to 3v I bought this one: PowerPOD 1117 3V3 £1
3. Bicycle lights (rear)
4. Hose adaptors to fit the generator inline with the hose
Other tools needed to build this tool
Step-by-step build instructions
First connect the generator to the hose and it is good to measure the voltage output at various stages to make sure that it is working. The electrical current from the generator goes in to the power pod. There are various voltage regulators which can be limited to one small componenet. I used the power pod as I am not very knowledgable in electronics and it seemed (and proved) convenient. I noticed now that there are better micro generators which will produce smaller voltage (3.6v). that would skip the power pod step.
Again test that you are getting the correct voltage from the genertor and regulator.
It was a bit tricky to get the bicycle lights to work. I basically connected the output to where the batteries are meant to be and short circuit the switch. The one I used had a push button and different flashing options. As I said above I would have liked it to flash but didn't manage.
ie. SketchUp files, CAD drawings, photos, video, technical drawings.