alt.energy.homepower

"Ulysses" wrote in
news:13sm0abgfku3a61@:

>
> "(PeteCresswell)" wrote in message
> news:c5ijs39mg1hg6flkr4upf6ioev26g267jm@...
>> Posted here bco the obvious expertise of group members in matters
>> electrical.
>>
>> Bicycle-mounted front wheel generator (alternator?) hub - puts
>> out AC.
>>
>> Numbers on the hub say 6 volts, 4 watts.
>>
>> Putting a volt meter on it, I get 3v at walking speed ( mph),
>> 6v at 5 mph, and more as speed increases. With me on it, I
>> don't see it ever getting up to 20v, but 10-12v could be fairly
>> common.
>>
>> From what I've heard, there is a problem with using bulbs wired
>> direct. You get a bulb that won't burn out at the higher
>> voltages, and it's dim where most of the riding happens - at 5-10
>> mph. It also goes out when the bike goes really slow or stops.
>>
>> I'm basically clueless re/electrical stuff, but what I've gleaned
>> so far is this:
>> ------------------------------------------------------------------
>> 1) Something called a bridge rectifier will convert AC to DC.
>>
>> 2) If I put a couple of NiCad batteries end-to-end, but
>> across the rectifier's output, they'll be charged when the
>> output exceeds 3 volts and supply 3 volts when the output is
>> less than 3 volts - limiting the voltage that any bulb or
>> LED emitter is subjected to about 3 volts.
>>
>> 3) There are myriad 3-volt LED lights out there that I can choose
>> from for the lighting part. Red, white, steady, flashing....
>> you name it, somebody's selling it.
>> ------------------------------------------------------------------
>>
>> Bottom line, I want maximum brightness when just noodling along
>> at 3-7 mph, but don't want tb burning out bulbs if/when I go down
>> a hill fast.
>>
>> My primary concern is the lighting that's visible to closing
>> traffic from my back. I avoid roads with any significant amounts
>> of traffic, but even in the quietest neighborhoods and parking
>> lots there's some exposure.
>>
>> The more light and the more attention-getting on the rear the
>> better, since I'm competing with cell phones, text messages,
>> email, and navigation screens.
>>
>> I use a hand-held flashlight for the front lighting and it works
>> well. (Lowe's TaskForce 4w LED... one *brave* little flashlight)
>> .. but I also want a token front light attached to the bike and
>> wired into the system in case some cop wants to get technical or
>> the hand-held fails when I still have to get back to my home.
>>
>> Am I on the right track? Seems like the capacity of the
>> rectifier would be a half amp max (4w/20v + fudge factor).
>>
>> One more time: I'm clueless about electrical stuff.
>> --
>> PeteCresswell
>
> You could make a bridge rectifier with four very small diodes and use
> an adjustable voltage regulator (LM317 Radio Shack). You would only
> need to add a couple of capacitors and resistors, one being
> adjustable, and the whole thing would be not much bigger than a book
> of matches. You could then choose 3 volts or 6 volts (3 would be
> easier) as long as the bulb does not use more than amps. If
> necessary you could use the bicycle for a heat sink. The Radio Shack
> regulator has the circuit diagram on the back of the blister pack.

I was thinking along the same lines -- (without the actual knowledge to
build it) -- if you wanted, you could rig the heat sink as hand warmer
grips!

Like four wheelers have hand warming grips, so when your batteries are
getting too much voltage you could shunt into resisters in the grips and
keep yer mits warm :)