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  #41  
Old March 7th 17, 08:42 PM posted to rec.bicycles.tech
Sepp Ruf
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lou.holtman wrote:
On Tuesday, March 7, 2017 at 5:11:29 AM UTC+1, Frank Krygowski wrote:


http://peterwhitecycles.com/images/p...lux-II-800.jpg


Still too much chroma, but a more realistic looking comparison than the
aperiodical illumination of Mr. White's rustic driveway:
http://baslerbikes.de/index.php/baslerbikes-2-Scheinwerfervergleich-2013-november.html

That is the headlight I use and it looks exactly the same on a pitch dark street.


Must be an extra-bright asphalt mix they use in NL - or simply a layer of sand.


--
Merkel's new StVZO aiming instructions: crescent just below line H-H
http://i.dailymail.co.uk/i/pix/2016/08/08/08/36FC213600000578-0-image-a-2_1470641631742.jpg


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  #42  
Old March 7th 17, 11:56 PM posted to rec.bicycles.tech
James[_8_]
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On 07/03/17 04:22, Jeff Liebermann wrote:
On Mon, 6 Mar 2017 17:04:13 +1100, James
wrote:

On 06/03/17 12:26, Jeff Liebermann wrote:

Well, let's do some arithmetic. If your dynamo is rated at 3 watts,
and your lighting is rated at 70 lumens/watt, then the most you can
perhaps deliver is 210 lumens. 6 watts will get perhaps 420 lumens.
Usually, it's less as the losses accumulate. Rectification losses,
optical losses, heat degradation, and connector losses all conspire to
produce lower output.


We know that a 3W dynamo is quite capable of delivering more power than
3W, once the bicycle speed increases. 6W from a 3W dynamo is quite
achievable, and the retardation torque drops off as speed increases too.


Maybe:
http://www.myra-simon.com/bike/dynotest.html
See "Electrical Output" graph.

Kinda looks like all of them will sorta deliver 2.5 watts before the
core saturates (to provide some level of voltage regulation). Further
down the page is a "Low Speed Power" graph, which shows that most can
produce 2.0-2.5 watts at 10km/hr. One could assume that the dynamo
will deliver 4.0 watts, but that would require buying one of the few
better (hub) dynamos listed, and riding at 25-30km/hr (15-19mph).

If I were designing or sizing a lighting system suitable for my slow
style of "cruising", I would use the worst case 10km/hr (6mph) and 2.0
watt figures.




Back to electrical engineering school for you, Jeff.

--
JS
  #43  
Old March 8th 17, 12:01 AM posted to rec.bicycles.tech
John B.[_3_]
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On Tue, 07 Mar 2017 10:38:38 -0800, Jeff Liebermann
wrote:

On Tue, 07 Mar 2017 20:00:47 +0700, John B.
wrote:

On Mon, 06 Mar 2017 20:10:21 -0800, Jeff Liebermann
wrote:

On Mon, 6 Mar 2017 16:57:41 +1100, James
wrote:

What if I don't want to play with batteries?

Then play with calcium carbide (produces acetylene gas) instead:
https://www.google.com/search?q=acetylene+bicycle+lamp&tbm=isch


Ahem! I don't think you should suggest acetylene gas devices to some
of the folks here. After all the safe limit for acetylene gas is 15
psi, above which it tends to go BOOM! :-)


I once found a patent for an acetylene lantern design that used the
heated gas pressure from the burning acetylene to pressurize a reed
and thus act as a horn. I don't recall if it had a built in red tail
light.

What keeps an acetylene lantern from blowing up and ruining a ride is
that the drip of water into the calcium carbide chamber is regulated
by the back pressure produced by the reaction. No water means no gas
is produced. It's a gravity fed affair, that's quite reliable and
should never raise the internal pressure anywhere near 15 psig.

Well, yes, that sounds like a very good idea, but.... Over here you
can still buy an "acetylene generator" used to provide acetylene gas
for a welding torch. These use the same system "no water, no gas" that
the lamps do. But unfortunately over years of use they get rusty,
dusty, corroded or just clogged up and every once in a while they do
explode. Usually with loss of life.

(but maybe if you wear a helmet and have a bright light... :-)


The light isn't for me. It's for James who wants an alternative to
changing batteries. I solved my lighting problem long ago:
http://802.11junk.com/jeffl/pics/bicycles/slides/bicycle-flashlight.html


:-} I solvd my problems using a much simpler solution... don't ride at night :-{


The big problem with an acetylene bicycle lantern is that a typical
lantern only delivers about 30 to 50 lumens (my measurements).

If you need a project, build an acetylene lamp that screws into an
aluminum water bottle.
http://www.4bobandbob.com/pages/pics/PremierDia.gif


Don't need a project. But back when I was shooting on A.F. pistol
teams we used "carbide lamps" to blacken the sights. Very simple
lights with a canister for the carbide and a igniter incorporated in
the reflector that you could flick with your thumb. Spit in the
carbide receptacle, hold your hand over the reflector for a second or
two and flick the igniter. POP (sometimes BANG) and you had a nice
"rich" flame to blacken the sights.

Quite a bright light too. I've used one to look for things in dark
corners and they seem to give off sufficient light. Much better than
my old Japanese bike with the bottle generator and the incandescent
light bulb anyway. And, of course, you didn't have to pedal them to
have lights :-)
--
Cheers,

John B.

  #44  
Old March 8th 17, 12:09 AM posted to rec.bicycles.tech
James[_8_]
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On 07/03/17 06:15, jbeattie wrote:
On Sunday, March 5, 2017 at 9:57:44 PM UTC-8, James wrote:
On 06/03/17 10:22, Barry Beams wrote:


Burn time: What if you had five or ten hours battery time at your
generator's brightness? My Oculus gives at least that much
brightness, and a quickly field replaceable battery so you can put in
a fresh battery. Other rechargeables leave you out of light and out
of luck when the battery drains. Oculus also comes with a spare
battery included.


What if I don't want to play with batteries?


Then you're done with the battery light discussion and may move on to helmets.


Now that you mention it...

I don't like putting sun screen on the top of my head because in the
heat and humidity I sweat a lot and it tends to run down into my eyes
and stings most painfully with sun screen mixed in.

So my foam hat has big ventilation holes that let the sun light through
to my scalp.

If I was allowed to ride without a foam hat I could keep the sun off my
scalp with a cloth cap, but that's not an option in this country.

If I develop a skin cancer on the top of my head, I shall seek to sue
the government, for their law makes adequate sun protection with
sufficient ventilation near on impossible.

--
JS
  #45  
Old March 8th 17, 12:16 AM posted to rec.bicycles.tech
James[_8_]
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On 07/03/17 18:58, wrote:
On Tuesday, March 7, 2017 at 5:11:29 AM UTC+1, Frank Krygowski
wrote:
On 3/6/2017 9:37 PM, sms wrote:

This light http://supernova-lights.com/en/supernova-e3-triple-2
claims 640 lumens at 4.5W. 4.5W is definitely possible from a
nominal 3W dynamo. It claims 800 lumens peak.

Note that his light, while sold in Germany, is not "road legal."
because, according to reviews, it doesn't suffer the problems of
StVZO lights, "It has a very broad light output that is closer to
a floodlight than a focused beam, and so doesn’t give the
‘tunnel’ effect of some of the powerful battery-powered lights.
This means it’s great for illuminating branches and hazards above
you and off to the side." As we all know, the problem with StVZO
legal lights are related to the extremely focused spot beam.


Here's an example of an StVZO headlamp (2013 model) with the
"extremely focused spot beam" the Scharf complains about.
http://peterwhitecycles.com/images/p...lux-II-800.jpg


See that tiny spot? ;-)


That is the headlight I use and it looks exactly the same on a pitch
dark street. So again I don't understand why people find this amount
of light insufficient.


But when you're riding home through the local forest MTB paths, and it's
snowing and there are overhanging branches and a Joerg or SMS comes the
other way with a blinding 1200lm torch beam.....

You might not see that salmon swimming across the path!

--
JS
  #46  
Old March 8th 17, 12:56 AM posted to rec.bicycles.tech
James[_8_]
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On 07/03/17 11:50, Jeff Liebermann wrote:
On Mon, 6 Mar 2017 20:10:38 +0000 (UTC), David Scheidt
wrote:

Frank Krygowski wrote:
:On Monday, March 6, 2017 at 1:37:23 PM UTC-5, AMuzi wrote:
: I don't know about currents but 6V 4W bulbs for standard
: dynamo systems have been around for twenty years and some
: customers like them. I don't know if the dynamo drag is
: noticeably greater.


:6V 4W? I'm aware of 6V 3W bulbs, which are (or were) used mostly with bottle
:dyno systems when driving a headlamp but no taillamp. They were an alternative
:to 2.4 W in front and 0.6W in back.


:I'm not aware of any common use of 6V 4W bulbs.


It's a standard lantern size.


http://www.rayovacindustrial.com/Products/Lights/Bulbs/K13-2TB-Krypton-Bulb-for-4D-Flashlights.aspx
Ray-0-Vac K13-2TB. Made for 4D cell lanterns. 6v 3.6 watts.
I couldn't find a 4 watt version. Most of what I found were 2.4 and
3.0 watt bulbs for bicycles.


A 6V 3W dynamo will easily power a 12V 6W bulb, but at higher speed.

In the same way, it has been tried and tested to install two 6V 3W
headlights, and a switch that can bypass one light, or connect the two
in series.

--
JS
  #47  
Old March 8th 17, 01:35 AM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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On 3/7/2017 3:42 PM, Sepp Ruf wrote:
lou.holtman wrote:
On Tuesday, March 7, 2017 at 5:11:29 AM UTC+1, Frank Krygowski wrote:


http://peterwhitecycles.com/images/p...lux-II-800.jpg


Still too much chroma, but a more realistic looking comparison than the
aperiodical illumination of Mr. White's rustic driveway:
http://baslerbikes.de/index.php/baslerbikes-2-Scheinwerfervergleich-2013-november.html

That is the headlight I use and it looks exactly the same on a pitch dark street.


Must be an extra-bright asphalt mix they use in NL - or simply a layer of sand.


I've noticed that the asphalt does lighten in color somewhat as it ages.
And I've noticed that dark road surfaces are not as visible in the
headlight beam. This is true even with car headlight beams; the dark
surface obviously reflects less light back to the operator's eyes.
(That's probably covered in the definition of "dark.")

This adds to the complexity of producing realistic screen shots of
headlight beams. And it's already complex enough, because different
camera exposure settings, different focal lengths, different lighting
environments, etc. make one website's beam shots look quite different
from another. Even if all testers used the same parameters, it might
not match what the human eye perceives.

If one were to develop an ASTM standard for headlight screen shots, all
those and other factors would have to be uniformly controlled.

Sounds like a good project for someone's masters' thesis.


--
- Frank Krygowski
  #48  
Old March 8th 17, 01:50 AM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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On 3/7/2017 7:09 PM, James wrote:
On 07/03/17 06:15, jbeattie wrote:
On Sunday, March 5, 2017 at 9:57:44 PM UTC-8, James wrote:
On 06/03/17 10:22, Barry Beams wrote:


Burn time: What if you had five or ten hours battery time at your
generator's brightness? My Oculus gives at least that much
brightness, and a quickly field replaceable battery so you can put in
a fresh battery. Other rechargeables leave you out of light and out
of luck when the battery drains. Oculus also comes with a spare
battery included.


What if I don't want to play with batteries?


Then you're done with the battery light discussion and may move on to
helmets.


Now that you mention it...

I don't like putting sun screen on the top of my head because in the
heat and humidity I sweat a lot and it tends to run down into my eyes
and stings most painfully with sun screen mixed in.

So my foam hat has big ventilation holes that let the sun light through
to my scalp.

If I was allowed to ride without a foam hat I could keep the sun off my
scalp with a cloth cap, but that's not an option in this country.

If I develop a skin cancer on the top of my head, I shall seek to sue
the government, for their law makes adequate sun protection with
sufficient ventilation near on impossible.


Now, now, now! This person in Melbourne
https://pricetags.files.wordpress.co...bike.jpg?w=560
proves that it's a simple matter to have sun protection, yet to have the
foam hat close enough to one's head for it's magic to be effective.

;-)

BTW, I've seen the same trick used in America. So I've learned that any
bike facility is a good bike facility, and a helmet anywhere near your
head will save your life.


--
- Frank Krygowski
  #49  
Old March 8th 17, 02:07 AM posted to rec.bicycles.tech
JBeattie
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Posts: 3,214
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On Tuesday, March 7, 2017 at 5:50:32 PM UTC-8, Frank Krygowski wrote:
On 3/7/2017 7:09 PM, James wrote:
On 07/03/17 06:15, jbeattie wrote:
On Sunday, March 5, 2017 at 9:57:44 PM UTC-8, James wrote:
On 06/03/17 10:22, Barry Beams wrote:


Burn time: What if you had five or ten hours battery time at your
generator's brightness? My Oculus gives at least that much
brightness, and a quickly field replaceable battery so you can put in
a fresh battery. Other rechargeables leave you out of light and out
of luck when the battery drains. Oculus also comes with a spare
battery included.


What if I don't want to play with batteries?

Then you're done with the battery light discussion and may move on to
helmets.


Now that you mention it...

I don't like putting sun screen on the top of my head because in the
heat and humidity I sweat a lot and it tends to run down into my eyes
and stings most painfully with sun screen mixed in.

So my foam hat has big ventilation holes that let the sun light through
to my scalp.

If I was allowed to ride without a foam hat I could keep the sun off my
scalp with a cloth cap, but that's not an option in this country.

If I develop a skin cancer on the top of my head, I shall seek to sue
the government, for their law makes adequate sun protection with
sufficient ventilation near on impossible.


Now, now, now! This person in Melbourne
https://pricetags.files.wordpress.co...bike.jpg?w=560
proves that it's a simple matter to have sun protection, yet to have the
foam hat close enough to one's head for it's magic to be effective.

;-)

BTW, I've seen the same trick used in America. So I've learned that any
bike facility is a good bike facility, and a helmet anywhere near your
head will save your life.


http://www.aerotechdesigns.com/cycli...protector.html Reasonable accommodation for the hair-differently-abled. Not recommended for wearing in Kansas, Washington or any other US state where one could be mistaken for a Sikh.

-- Jay Beattie.
  #50  
Old March 8th 17, 02:15 AM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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On 3/6/2017 2:12 AM, DATAKOLL MARINE RESEARCH wrote:
Assumptions or measured ?


I forgot to respond to that question.

I've measured dynamo torque vs. speed. As James says, the resistance
torque of a dyno decreases as speed increases. It doesn't decrease as
much as speed increases, however, so the power required still increases
with speed.

Example: Soubitez roller dynamo

Speed (mph) 6 12 18 24
Torque (N*mm) 26.4 22.6 18.1 14.3 with 12 Ohm load
Torque (N*mm) 22.6 23.4 19.6 15.1 with 24 Ohm load

I found similar behavior with other dynamos.

With an open circuit, drive torque did increase with road speed.

--
- Frank Krygowski
 




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