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  #101  
Old March 13th 17, 08:19 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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On 3/13/2017 2:06 PM, Joerg wrote:

Then you'd be back to this inferior dynamo lighting which goes out at
the traffic light, or uses dimmed or short-lived light if there is a
supercap installed.


Where are the tragic tales of cyclists who are seriously injured or
killed because their dynamo standlights were too dim or too short-lived?
Somehow those tales have failed to make it into the safety literature!


--
- Frank Krygowski
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  #102  
Old March 13th 17, 08:28 PM posted to rec.bicycles.tech
Joerg[_2_]
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On 2017-03-13 11:50, sms wrote:
On 3/13/2017 11:06 AM, Joerg wrote:

snip

That's how some cheap Chinese chargers work.


And a lot of non-Chinese chargers as well.

Not good as that is no
lomnger single-fault safe. It is as if you'd control a pump via tripping
a GFCI when a certain fill level has been reached.


Technically there are two safety circuits. First, with an 8.4V output
charger you're limiting the charging voltage to 4.2V per cell.



That doesn't really work because then the charge current would all but
vanish towards the end, a charge would take forever. You've got to
monitor cell voltage twice, once from the charger side and then in the
cell protector circuitry.


... Second,
the protection circuit on each battery, or on the battery pack, limits
the voltage to 4.2V per cell just in case someone plugs in a higher
voltage charger.


The usual bicycle packs have only one such supervisor ciruit and then
the bare cells.


I think the simplest dynamo to Li-Ion 2S pack circuit would consist of
only three parts. A 2A Schottky bridge. A filter cap. An 8.2V, 5W zener
diode. I don't think you even need a current limiting resistor because
the dynamo isn't going to put out much more than 500mA.


Zeners have huge tolerances. I wouldn't do that. If you must use a shunt
limiter at least employ a TL431 plus a big transistor or FET. Those are
way more accurate and just as cheap.


I don't think you gain much with a buck switcher unless you're often
putting out dynamo voltage well in excess of 6VAC, or unless you want to
do 5.25V for USB charging. You're going to lose some power with the
switcher which is likely to be only 85%-90% efficient.


You'd gain a lot. An old trick for well-trained commuter cyclists was to
hang two lights in series for 12V which resulted in a lot more power and
thus light. For slower pace one lamp could be shorted out.


You could stick in a Murata LXDC55FAAA-203
http://power.murata.com/data/power/LXDC55FAAA-203_data_sheet_E.pdf
instead of the zener and do a USB version also with only three parts.
But I know that you love designing your own switchers.


$3.50? Mon Dieu! :-)

My main gripe would be the 14V limit. I'd like this to be able to go a
tad higher for long downhill stretches.

I don't enjoy designing switchers all that much anymore after having
done 50-100 professionally. Gets boring.


I'm in shock when I see the prices of some of these dynamo to USB
adapters, since the parts cost is only a few bucks.

http://www.sinewavecycles.com/products/sinewave-revolution


I often have the impression that cyclists get taken advantage of.
However, in this case the produced quantities will likely be so low that
they have to charge a lot. It's not going to be a roaring market success.


Here's someone that did it DIY but using a linear regulator.
http://www.14degrees.org/diy-bicycle-dynamo-usb-charger-for-smartphones-and-battery-packs/


One of my bicycle rear lights (homemade) contains two MC34063. Not
terribly efficient but it can safely be used to a little over 30V and
costs 50 cents even if you only buy one. Can be pilfered from scrapped
electronics. Diodes Inc makes one on steroids that goes ... hold on to
your hat ... to 180kHz :-)


At lower output levels, a dynamo could even run a 2 cell battery powered
light if the batteries were removed.



Then you'd be back to this inferior dynamo lighting which goes out at
the traffic light, or uses dimmed or short-lived light if there is a
supercap installed.


No, I'm more thinking of a way to have a good light but with dynamo
back-up should the batteries go flat. As well as charging the batteries
during daytime riding when all you're using is the DRL flash mode.


That would be my goal. I have good lighting on both bikes but on the
road bike it would be nice to have a dynamo in the game. Like a hybrid
car which combines gas and electric. Over the course of a long ride 50%
of the juice would come from the dynamo and 50% from the battery,
allowing to use half the number of cells. Should I ever ride more than
5-6h I could dim the front light and milk the dynamo for 80-90% of the
budget. Or use more MUP where I can turn the lights off and then the
dynamo would deliver a net average of 100%, only the road sections where
I need full bore and have to wait at signals would need to be covered by
the battery.


Unfortunately, since dynamo lights are so rare in the U.S. we end up
with sub-standard lighting with poor beam patterns, low intensity, no
flash mode, and inferior brightness when stopped or riding slowly.

I thought it was interesting that Barry Beams mentioned that his light
could work, at less than full intensity, off of dynamo output. He may
have a compelling product for dynamo users that want a brighter, safer,
light but that still want the assurance of not being caught out with
flat batteries. Even Frank realized the need for better lights and
bought an Oculus. And while the Oculus may not be a bargain battery
powered light (even though the price is still pretty reasonable), it's a
lot less than dynamo lights that are not as good.


I'd keep my lights as-is, MagicShine clones with diffusor lenses. The
dynamo would just be added into the mix, doing the same as the
alternator on a car except at standstill.

--
Regards, Joerg

http://www.analogconsultants.com/
  #103  
Old March 13th 17, 08:38 PM posted to rec.bicycles.tech
Joerg[_2_]
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On 2017-03-13 11:55, Jeff Liebermann wrote:
On Mon, 13 Mar 2017 11:06:18 -0700, Joerg
wrote:

A dynamo is essentially a current source where you can let
the voltage scoot up until a point is reached where the current drops
off so much that the total power begins to drop. Like MPPT for solar
generation.


Not exactly a current source. More like a resistor (coil resistance)
in series with an easily saturated inductor[1]. The problem is that
the bicycle dynamo operates over a range of frequencies, while the
typical solar charge controller operates at a fixed frequency. The
inductive reactance of the dynamo winding appears at variable series
resistance that increases as the dynamo goes faster. There are also
substantial differences in operating frequency between bottle and hub
dynamos:
http://www.pilom.com/BicycleElectronics/HubDynamo.htm
"Hubs rotate at a much lower frequency than bottles, and
though they have more poles to somewhat compensate, they still
end up delivering a much lower frequency. At 15 km/h, the
B&M Dymotec6 bottle dynamo (8 poles) outputs 168 Hz AC while
the Shimano DH-3D71 hub dynamo (28 poles) outputs only 28 Hz
at the same speed. At 8 km/h, a 28 pole hub is down to 15 Hz,
which causes visible flicker of the light"


However, in your link they say, quote "Hubs don't go into saturation
easily so that at moderate to high speed, they develop a higher voltage
than bottle dynamos, assuming they are not loaded with the typical 6 V /
3 W lights. To see whats possible, I ran a Shimano DH-3D71 at 136 km/h
in a test stand. The voltage generated was sufficient to ignite a
fluorescent tube and subsequently drive it at 55 V and 500 mA".

55V at 500mA. This is encouraging.

Highe power at high voltage also works with bottle dynamos. I have tried
with a Soubitez and a Ruhla dynamo, never a hub dynamo though because I
never had one.


Also, the dynamo iron and number of turns are selected so that the
dynamo saturates at some point near the operating speed and load. The
idea is not so much to regulate the AC output, as it is to reduce
mechanical resistance at higher RPM's.


I could make 12V filament lighting glow like halogen at high speed.


I tried to build an LTSpice model that simulated a real dynamo and
failed. I couldn't make it act like my bottle dynamo bench tests and
various online graphs. Maybe I'll try again this week. I'm suppose
to be on a (medical) vacation right now.


It's best to try that out on the bench, using a rechargeable drill and such.



[1] SON dynamo driving MOSFET bridge:
https://www.flickr.com/photos/kurtsj00/8480800746/in/photostream
http://www.candlepowerforums.com/vb/showthread.php?355392-Spice-code-for-dynamo-output



"CPF is currently closed for maintenance".


The author uses 0.1Hy in series with 2 ohm at 30 Hz. When I swept the
30 Hz over a 10 to 50 Hz range, it didn't look much like a dynamo.


--
Regards, Joerg

http://www.analogconsultants.com/
  #104  
Old March 13th 17, 08:50 PM posted to rec.bicycles.tech
Joerg[_2_]
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Posts: 6,016
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On 2017-03-13 12:19, Frank Krygowski wrote:
On 3/13/2017 2:06 PM, Joerg wrote:

Then you'd be back to this inferior dynamo lighting which goes out at
the traffic light, or uses dimmed or short-lived light if there is a
supercap installed.


Where are the tragic tales of cyclists who are seriously injured or
killed because their dynamo standlights were too dim or too short-lived?
Somehow those tales have failed to make it into the safety literature!


As we all know reports of fatal car-cyclist collisions are notoriously
short on details.

You claim to be something like a "teacher for safe cycling" yet you
don't know or ignore the most basic safety precautions. Astounding.
Actually, sad.

--
Regards, Joerg

http://www.analogconsultants.com/
  #105  
Old March 13th 17, 09:08 PM posted to rec.bicycles.tech
SMS
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Posts: 9,477
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On 3/13/2017 12:50 PM, Joerg wrote:
On 2017-03-13 12:19, Frank Krygowski wrote:
On 3/13/2017 2:06 PM, Joerg wrote:

Then you'd be back to this inferior dynamo lighting which goes out at
the traffic light, or uses dimmed or short-lived light if there is a
supercap installed.


Where are the tragic tales of cyclists who are seriously injured or
killed because their dynamo standlights were too dim or too short-lived?
Somehow those tales have failed to make it into the safety literature!


As we all know reports of fatal car-cyclist collisions are notoriously
short on details.

You claim to be something like a "teacher for safe cycling" yet you
don't know or ignore the most basic safety precautions. Astounding.
Actually, sad.


Unless their is a case-controlled, double-blind, study, Frank won't
believe that increasing visibility at night, both for seeing and being
seen, is beneficial.

Following that to its logical conclusion, he should be opposed to any
lighting at all. Or at least he should be able to provide a chart of
accidents versus lumens to prove that there is no benefit to a cyclist
improving his or her conspicuity and his or her ability to see the road
and off to the sides.

Yet there are numerous studies that have been cited in this group that
do prove the benefits of better conspicuity.

  #106  
Old March 13th 17, 10:25 PM posted to rec.bicycles.tech
Joerg[_2_]
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Posts: 6,016
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On 2017-03-13 13:08, sms wrote:
On 3/13/2017 12:50 PM, Joerg wrote:
On 2017-03-13 12:19, Frank Krygowski wrote:
On 3/13/2017 2:06 PM, Joerg wrote:

Then you'd be back to this inferior dynamo lighting which goes out at
the traffic light, or uses dimmed or short-lived light if there is a
supercap installed.

Where are the tragic tales of cyclists who are seriously injured or
killed because their dynamo standlights were too dim or too short-lived?
Somehow those tales have failed to make it into the safety literature!


As we all know reports of fatal car-cyclist collisions are notoriously
short on details.

You claim to be something like a "teacher for safe cycling" yet you
don't know or ignore the most basic safety precautions. Astounding.
Actually, sad.


Unless their is a case-controlled, double-blind, study, Frank won't
believe that increasing visibility at night, both for seeing and being
seen, is beneficial.

Following that to its logical conclusion, he should be opposed to any
lighting at all. Or at least he should be able to provide a chart of
accidents versus lumens to prove that there is no benefit to a cyclist
improving his or her conspicuity and his or her ability to see the road
and off to the sides.

Yet there are numerous studies that have been cited in this group that
do prove the benefits of better conspicuity.


The topper was a car driver. It was foggy and she was tearing down a
freeway. One passenger said "That's dangerous to drive so fast here, you
can barely see!" ... "Oh, that's ok. Because the others won't see much
either".

--
Regards, Joerg

http://www.analogconsultants.com/
  #107  
Old March 14th 17, 01:19 AM posted to rec.bicycles.tech
Sir Ridesalot
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Posts: 5,270
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On Monday, March 13, 2017 at 2:09:05 PM UTC-4, Joerg wrote:
On 2017-03-12 15:21, James wrote:
On 13/03/17 01:57, Joerg wrote:
On 2017-03-11 16:28, Sir Ridesalot wrote:



You need to look again at more modern stuff because many dynamo
hub standlights are quite bright for the time they stay on usually
a ferw minutes or so if needed. But then again absolutely NOTHING
ever works for you off the shelf.


Wrong, it does and I have written about it here in the NG. I bought
a Cree XM-L based light each for the road bike and the MTB. Of
course, since almost nothing in the world of cycling is very robust
or complete this had to be spiced up. Both lights got diffusor lenses
because they will otherwise blind others and the light distribution
wasn't to my liking. Big deal, you just buy diffusor lenses and
install them. Then the battery holders are lousy. This took a little
more work but nothing that can't be done with a trip to the hardware
store and basic hand tools:

http://www.analogconsultants.com/ng/bike/Battbox2.JPG


You just proved Sir's point. Well done Joerg.


Huh? I made it quite clear that my solution works. It does very well.

--
Regards, Joerg

http://www.analogconsultants.com/


Because NOTHING works for you umn.ess you modify it.

Cheers
  #108  
Old March 14th 17, 01:36 AM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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Posts: 10,538
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On 3/13/2017 4:08 PM, sms wrote:
On 3/13/2017 12:50 PM, Joerg wrote:
On 2017-03-13 12:19, Frank Krygowski wrote:
On 3/13/2017 2:06 PM, Joerg wrote:

Then you'd be back to this inferior dynamo lighting which goes out at
the traffic light, or uses dimmed or short-lived light if there is a
supercap installed.

Where are the tragic tales of cyclists who are seriously injured or
killed because their dynamo standlights were too dim or too short-lived?
Somehow those tales have failed to make it into the safety literature!


As we all know reports of fatal car-cyclist collisions are notoriously
short on details.

You claim to be something like a "teacher for safe cycling" yet you
don't know or ignore the most basic safety precautions. Astounding.
Actually, sad.


Unless their is a case-controlled, double-blind, study, Frank won't
believe that increasing visibility at night, both for seeing and being
seen, is beneficial.


Oh, come on, Stephen. People getting hit because their standlights are
too dim? We don't even have anecdotes about that!


--
- Frank Krygowski
  #109  
Old March 14th 17, 01:58 AM posted to rec.bicycles.tech
Doug Landau
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Posts: 1,424
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On Monday, March 13, 2017 at 5:19:14 PM UTC-7, Sir Ridesalot wrote:
On Monday, March 13, 2017 at 2:09:05 PM UTC-4, Joerg wrote:
On 2017-03-12 15:21, James wrote:
On 13/03/17 01:57, Joerg wrote:
On 2017-03-11 16:28, Sir Ridesalot wrote:


You need to look again at more modern stuff because many dynamo
hub standlights are quite bright for the time they stay on usually
a ferw minutes or so if needed. But then again absolutely NOTHING
ever works for you off the shelf.


Wrong, it does and I have written about it here in the NG. I bought
a Cree XM-L based light each for the road bike and the MTB. Of
course, since almost nothing in the world of cycling is very robust
or complete this had to be spiced up. Both lights got diffusor lenses
because they will otherwise blind others and the light distribution
wasn't to my liking. Big deal, you just buy diffusor lenses and
install them. Then the battery holders are lousy. This took a little
more work but nothing that can't be done with a trip to the hardware
store and basic hand tools:

http://www.analogconsultants.com/ng/bike/Battbox2.JPG


You just proved Sir's point. Well done Joerg.


Huh? I made it quite clear that my solution works. It does very well.

--
Regards, Joerg

http://www.analogconsultants.com/


Because NOTHING works for you umn.ess you modify it.


So he's a tweak snob. I point my saddle 1 degree to the right 'cuz my left nut is bigger.

Cheers is right
  #110  
Old March 14th 17, 02:39 AM posted to rec.bicycles.tech
John B.[_3_]
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Posts: 5,697
Default More About Lights

On Mon, 13 Mar 2017 10:14:55 -0000 (UTC), Duane
wrote:

jbeattie wrote:
On Sunday, March 12, 2017 at 7:57:46 AM UTC-7, Joerg wrote:
On 2017-03-11 16:28, Sir Ridesalot wrote:
On Saturday, March 11, 2017 at 10:38:39 AM UTC-5, Joerg wrote:
On 2017-03-10 19:40, Sir Ridesalot wrote:
On Friday, March 10, 2017 at 7:52:30 PM UTC-5, Joerg wrote:
Snipped
With or without dynamo I'll never ride without a battery
because then it's lights out when waiting at an intersection.
Very bad at night.

Now, about the bicycle air conditioner ... :-)

-- Regards, Joerg

http://www.analogconsultants.com/

Most decent dynamo ights these days have a standlight that'll run
for several minutes when the bicycle is stopped.


I have seen that in Germany. Standlight was very dim though. I
prefer it to be lit normal like it is on my bikes.

-- Regards, Joerg

http://www.analogconsultants.com/

You need to look again at more modern stuff because many dynamo hub
standlights are quite bright for the time they stay on usually a ferw
minutes or so if needed. But then again absolutely NOTHING ever works
for you off the shelf.


Wrong, it does and I have written about it here in the NG. I bought a
Cree XM-L based light each for the road bike and the MTB. Of course,
since almost nothing in the world of cycling is very robust or complete
this had to be spiced up. Both lights got diffusor lenses because they
will otherwise blind others and the light distribution wasn't to my
liking. Big deal, you just buy diffusor lenses and install them. Then
the battery holders are lousy. This took a little more work but nothing
that can't be done with a trip to the hardware store and basic hand tools:

http://www.analogconsultants.com/ng/bike/Battbox2.JPG

Why would I want inferior light when I can have a Cree XM-L that affords
me almost the same quality light as a motorcycle has?

This light doesn't just offer a few minutes of "standlight", it offers
north of five hours of light at full blast, whether the bike move or
not. I also have a power outlet on the bike.


Hmm, I've managed without a battery box, outlet and motorcycle light on a
road bike for like 50 years. I was riding up and down narrow canyons and
city streets today without so much as a blinky. The one car that pulled
out in even a semi-perilous fashion did so while looking straight at my
son and me. No question of our location on the road. I get cars doing
the same thing when I'm in a car. They think they can beat you into traffic.


You gotta love the way he starts out telling Sir that Sir is wrong and then
doing exactly what Sir said that he does. :-)

I seem to get by with off the shelf equipment though I readily admit that I
haven't seen a mountain lion in ages.


But you probably aren't riding up mountain sides, leaping rocks and
riding through rivers, usually at 20 mph, either.
--
Cheers,

John B.

 




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