On Mar 14, 8:36*pm, "(PeteCresswell)" wrote:
What light bulbs/LED emitters are you powering with your
Sturmey-Archer Dynohub?

Front? * Back?

I did the thing with the bridge rectifier to convert it's output
to DC - figuring I'd drive some LED emitters to get max light.

But I'm having problems with the voltage regulator part. I get
the circuit tuned to put out, say, 1.5 volts with 6 volts coming
in from a 4-battery test source and then when I put another
battery in series, the output voltage rises to 2.something.

Probably something dumb I'm doing in the regulator, and I expect
to do it right eventually.

But it got me to wondering how voltage-tolerant light bulbs and
LEDs are. * My assumption going into this has been "not very",
but I don't have much to base that on.

Am I doing the voltage regulation piece in vain? *Do I really
need regulation? * When I hang a voltmeter on the DC output it
varies from 3 volts at a walking pace to about 20 volts on a
downhill.

So, bottom line, who is using what without toasting a lot of
bulbs yet getting plenty light?
--
PeteCresswell

In the tradition established in this thread: I was educated as an
economist and psychologist and became an artist who occasionally
publishes books on engineering as well. But I do know a little about
electronics, in that I've worked for fifteen years or so with the
kilovolt thermionic tube amplifiers I design and build.

1. I'm assuming your Sturmey-Archer dynohub is rated the same as every
other dynohub, which is theoretically 6V 0.5A or 3W. It will in fact
probably deliver more as it is built to German regulations that demand
a high percentage of its total output at the equivalent of only 9mph.

2. The standard assignment of this power is 0.6W to the rear light and
2.4W to the front light; this assumes that the front light is halogen
and the rear a red LED, so, if you don't lead any power to the rear,
you can use a 3W front halogen.

3. Forget a dynopowered rear light of any kind. Even the best are
dangerous to your health. The expensive BUMM ones are not watertight
and the best of the rest, made by Basta (I have one they custom make
for Gazelle but it is basically just an aesthetic variation of their
best rear lamp) and by Spanninga (their Ultra; I have that one as
well) are merely better waterproofed, not more illuminative. I keep
them on my bikes simply because they came with the bikes. Even the
best of the dynodriven rear lights are little glimmers that you can
barely see across the street. None of the dyno-driven rear lights
flash, because it is streng verboten to have flashing lights in
Germany and The Netherlands, their prime markets.

4. Get a battery rear light. If you're rich, get a Dinotte rear light
(ask Jay; he has one), if not a Cateye TL-LD1100, which is pricey
enough. There is only one other taillight that is good enough for your
life and that's the Trek Disco Inferno, which is no longer made. The
Dinotte and the Cateye 1100 are *bright*, they cast very substantial
light to the sides as well as the rear, and they flash. Those are the
minimum requirements for good taillights, and they are the only ones
who truly meet them. The Cateye 1100 is bright enough to be seen in
bright sunlight; I use it as a daylight running lamp. It is supposed
to last 200 hours on a set of 2 AA batteries; I don't know how long
the batteries last in hours because I use rechargeables and swap them
out every three or four months or so.

5. Now you're ready to consider your front light. Your dynohub will
power halogen or LED lights that will give substantial light.

6. For a start, if you ride faster than about 10mph, you can fit a
second halogen light and the dynobub will power both of them. A
circuit is on the netsite of a guy who comes to RBT, name of Marten I
think; possibly the firm is called M-Engineering. Peter White also has
a circuit. You don't need the expensive SON lights; all they are are
Bisy lights with switches, or BUMM lights with switches. You can buy
the cheapest BUMM (round) halogen lights and make your own switchbox
-- I made one with a three-position switch (off, one on, both on) in a
plastic pill container and sealed it with superglue and fixed it to
the handbars with a fat rubber band.

7. Or you might want to considering overvolting a single halogen lamp:
you get far more light and you won't blow a Philips MR16 or MR11
longlife unit --anyway, what do you care if you reduce a 3000 mtbf
lamp to 1500 hours of life if you get nearly twice as much light? The
trick is that you must be able to get them in the 6V versions to work
with your dynohub, and the 6V MR16 or MR11 are not easy to find, at
least not where I live. But, once you have the right voltage lamp,
they're incredibly easy to work with. I built a lamp with a common
decorating type of MR16, 12V 20W, by simply soldering wires to the
pins (you can buy plugs for the pins at any lamp store, electrical
goods store or hardware store but they're more expensive than the
lamps themselves which are supermarket items), glueing the lamp into a
small Roma tomato puree can (it is exactly the right size) and glueing
the wires into a hole in the back for strain relief; I overvolted it
with the 14.4V battery from my drill, and fixed it to the handlebars
with a clamp from a throwaway rear light I bought at the pound shop
(US "dime store") specifically for this purpose. It made a stunning
lamp, earning a lot of respect from drivers, and was capable of going
for a ten mile ride on narrow country lanes with the drill battery.
(Eventually I bought readymade lights because the package was cheaper
than buying suitable rechargeable batteries, charger, case and so
on.)


8. Or, in LEDs, you can fit as many low consumption LEDs as you can
power. Each LED drops y volts, so the total must add up to what your
dynohub produces or must be regulated. You might want to look into
buckpucks to get the voltage right. Frankly, I wouldn't mess with LEDs
unless I could get the latest and the best, together with some means
of focusing the light correctly, and were also willing to sacrifice an
existing set of lights with hefty, preferably cast ali, shells for
cooling the LEDs. I looked into LEDs and decided that BUMM's Fly IQ
(at the expensive end of their range, which is generally overpriced)
would probably in the end cost less than messing around trying to make
my own.

9. If you're cheap or poor, consider this. Plenty of RBT dickswingers
will now weight in with how fabulous their BUMM Fly IQ is; I have one
too and it is a good light. However. A couple of halogen 2.4W lamps --
because that is what I had at the time of the test; 2x 3W lights would
do better still -- made as much light as the Fly at any speed over a
crawl and could be better arranged because the two lamps had different
spreads. The problem with a single light, any single light but
especially those driven by dynohubs where the output is by definition
limited, is that it is optimized for some particular patch, and there
isn't enough power to light up everything. With two lights you can
light the hole in front of the bike as well as the distance, and by
angling the two lights carefully either have a smooth spread or
distribute the available light to suit your preference. Example: I
ride on narrow lanes with a high crown and a very sudden drop-off into
the ditch -- I want to see both sides of the lane close to the bike,
and on the downhill i want to see the curves well ahead; no one dynamo
light can do both; in fact, even in big battery lights I use two
separate lamps, each dedicated to one desirable purpose.

10. Lights are the last bicycle frontier. We hear a lot of talk from
the technofreakies about how dynamo lights are now so much better than
they were. But better isn't automatically good enough. The best dyno
front light is still only nearly as good as a 10W MR11 battery light
-- whereas I don't feel comfortable on any aspect of lighting (being
seen, having my space respected, seeing) with anything less than about
25W divided between two lamps. YMMV, of course.

11. In summary: I recommend the Cateye TL-LD1100 battery rear light,
and two cheap BUMM halogen lights driven off the dynamo at the front
with a homemade switch, supplemented in case of regular commuting or
any strenuous riding circumstances by a rechargeable battery front
light set .

12. A simple test of whether lights are good enough is to go to the
most dangerous road you ride on and check when drivers first see you
and how they react. If more than one out of ten drivers don't see you
and react appropriately until you sweep a light directly through his
eyes, the lights are not good enough. The most dangerous road I ride
at night is less than a minute from my house and is ideal for setting
up an experiment because it is dark and has a hill to define the
driver's first sight of the bicyclist. I found that with 10W of
illumination on the bike, drivers 180 yards away did not slow after
the crest, with 15W some slowed, with 25W almost all slowed, and the
idiots would slow instantly if I swept that much light through their
eyes at 100 yards. That's still less than a quarter the light output
of a car putting two 55W beams on high to warn another driver.

13. Good strong lights are useful in daylight too. The flashing Cateye
1100 persuades a lot of people to slow behind me and to give me a
wider berth than they did before I fitted that light. The key for a
cyclist is to be seen and thought about. (When Jay has a bit more
experience with his Electra, he will notice that his higher profile on
the bigger -- and clearly expensive -- bike earns him more courtesy
from drivers than was the case on his old folder.)

14. That applies to front lights as well. Example: Yesterday
afternoon, while I was riding down a hill on another narrow road with
parked cars on both sides, a driver coming from the front clearly
intended, despite the fact that I had right of way, to bull his way
past me by forcing me to stop and pull off. I switched on my front
lights as a warning that I had seen him and had no intention of giving
way, and he immediately had second thoughts, pulling out of my way
between two parked cars to give me the road. A woman who was driving
behind me also drove into the supermarket where I stopped. "You
frightened that pushy son of a bitch ****less," she said, laughing
aloud; it turned out he's her unloved neighbour and people have been
talking about his foul manners on the hill to the estate where they
live.

15. I'm planning on fitting a flashing high-power white or amber LED
at the front, to operate whenever I'm on the bike including daylight,
because the flashing Cateye red at the back has been so successful. I
just haven't worked out yet if it will battery driven or if I should
let the dynohub drive it. An attractive option would be a pair of good
LED lights, with additional electronics to flash one, switched to come
on in steady mode when required.

16. If you buy one of the German or Dutch rear lights I'm advising
against, don't bother to get the self-switching one. I have three, and
I take potluck about when any of them are in manual-on-off or auto-on-
at-dusk mode because I cannot work out how to switch the modes.
Furthermore, one of them at least does not meter light reliably and is
confused by the common sodium type of street lights, and the motion
sensor has been inoperative from new. (By contrast the light sensor on
my Cyber Nexus groupset on my Trek Navigator works flawlessly to
switch on my dynohub-driven front light at dusk and off again at dawn.
Shimano used to make a light sensor/switch combo that reputedly worked
well too with dynohubs, but it is a long time since anyone had stock
of it.)

HTH.

Andre Jute
http://members.lycos.co.uk/fiultra/
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review