Starting to explore & play

Yeovil

I obtained the necessary LEDs from America at a reasonable price, got the optics and heat sinks from Germany and started to play with them to find out what was obtainable. The following is a writeup to one of the forums explaining what I had in mind.

Hi I just registered this evening, but have been following your write-ups on using the seoul LEDs I had just discovered them myself prior to discovering your forum on the same subject. I am interested in organising myself some L. E. D. bike lamps, and to add more meat to the subject I also am an avid dynamo user, the reason being I like to go touring on my bike and the dynamo is my only consistent power source. Last year I did a month in France with a normal bottom bracket dynamo charging a pack of two AAcells, in retrospect this was not enough and my hastily constructed bridge rectifier was not sufficient for the power output and on one particularly good downhill run the rectifier popped, at least that's what I thought happened because it ceased to work even though the dynamo still put out power at the lights.
I have not constructed my lamps yet, but I do have the lenses for them, I am using a couple of six degree by 25 degree beams and one very narrow beam which needs a different holder than the rest, the P4 emitters are coming from the USA the pretty way via Hong Kong.
My proposed setup will be two banks of four AA cells in series giving approximately 10 volts input for a good stable output from an LM317T variable voltage regulator, I am hoping to regulate the current through the leds by simply running them in their operating parameters by forward voltage control; as the LM317T has over current protection in the region of one half amps and one p4 is capable of 1000 milliamps, with three LEDs in circuit they should be adequately protected from over current by the natural shutdown protection of the device itself so it probably could run at 1 amp all things being well which will mean approximately 350 milliamps each LED.
The power supply will also be used to charge my mobile phone/MP3 player/satellite navigation receiver without having to worry about supermarkets being shut on Sunday or having to buy batteries.
Charging the batteries by means of the Hub dynamo and bridge rectifier, with a double pole double throw centre off switch charge each bank of batteries separately, this can be done when most convenient during daylight hours taking advantage of downhill runs etc. and of course when using the lights. I am not quite sure how am going to configure the actual lights themselves, but I am rather interested in that http://ktronik.com/index.html hardware! looks really plush.
Also I am very interested in achieving maximum output from my Shimano Dyna hub.Anyone want to pick holes in my idea you are very welcome to do so, you may think of something I haven't or see a potential problem, anyway it is thanks to this forum that I have done this much already. Thanks chaps.


I had some very good feedback from the members, and some suggestions that my idea was not very good, I refer to that of using the voltage regulator as my prime limiting device.
After playing with that voltage regulator I found that it was not suitable really although I had not done any damage to any of the LEDs I decided not to continue in that direction.


http://www.cyclingplus.co.uk/forum/topic.asp?TOPIC_ID=124379&whichpage=2

Some very good writeups on that above link