"white" LED's vs. incandescent and halogen lights

"white" LED's vs. incandescent and halogen lights

Post by thirty-si » Wed, 16 Dec 2009 05:03:52



Quote:

> First, if you use two LEDs in anti-parallel, there is no rectifying
> needed. ?One conducts the positive half of the waveform and thus
> protects the other from excessive reverse voltage; the other does the
> same for the negative half of the waveform.

Good point.  The conducting junction will keep the supply voltage down
from the generator as long as it is drawing a decent current.

Quote:

> Second, regulation isn't needed with a typical bike generator.
> They're naturally constant current devices, and the (essentially)
> fixed half amp they produce is fine for most high-powered white LEDs.

> That's how I visualized it, that's what happened when I bench tested
> it, and that's what I was told by a friend of mine who's vice
> president of engineering research for a firm that builds lighting
> systems from high performance LEDs.

Edit point--*

Quote:
> ?Using similar logic,
> cranksets for bicycles are too expensive! Why? Because a Campy carbon
> crank costs over $600. ?Therefore, we should all scoot along with our
> feet on the ground, Draisienne-style!

It would be way more efficient.  No need to supply a crank support
bearing and framework.  Just use extendable stilts and  variable
saddle height on a cantilevered beam.  Hmmmmn.
 
 
 

"white" LED's vs. incandescent and halogen lights

Post by Just zis Guy, you know » Wed, 16 Dec 2009 05:23:00



Quote:
>LOL, I was referring to the dynamos sold by Peter White, not the ones
>sold by Yellow Jersey 37 years ago.

http://www.simpsoncycles.co.uk/product.php?xProd=1937

34.99 (under 60 of your colonial dollars). I have one, it works
flawlessly and will comfortably power a B&M IQ Cyo which produces 60
Lux, which is five times the German legal required light output.

Looks like your guesstimates are a bit out of line.

Incidentally, it looks like the Cyo will fit a Brom with pannier (the
IQ Fly did not).  Has anyone tried this?

Guy
--
http://www.chapmancentral.co.uk/urc
GPG public key at http://www.chapmancentral.co.uk/pgp-public-key.txt

 
 
 

"white" LED's vs. incandescent and halogen lights

Post by SMS » Wed, 16 Dec 2009 05:37:55

Quote:






>>>> That's the crux of the problem. Rectifying the AC to DC, filtering it,
>>>> and regulating the voltage or current, isn't difficult or expensive, but
>>>> there's a big penalty in terms of efficiency, and you can't afford those
>>>> efficiency losses with a dynamo.
>>> Care to quantify "big penalty"? Coz LED dynamo lights are out there,
>>> front and rear, and are darned bright.
>> Can you quantify "darned bright" first?

> Stop ducking the question in the manner of a 5-year-old in a school
> playground.

LOL, so I guess you can't quantify "darned bright" huh?

The loss of efficiency in rectification and regulation has been
explained here numerous times. I'm sure you can google it. Unlike
"darned bright" the loss of efficiency is an actual quantifiable number
based on the buck-boost regulator efficiency and the efficiency of a
full wave bridge rectifier.

Even at the maximum theoretical efficiencies you're still at only xx%
(your homework is to Google the maximum efficiency of a buck boost
switching regulator, and a bridge rectifier and multiply the two numbers
together).

 
 
 

"white" LED's vs. incandescent and halogen lights

Post by Peter Col » Wed, 16 Dec 2009 05:54:16

Quote:

> The loss of efficiency in rectification and regulation has been
> explained here numerous times.

As has the lack of need for either (also at least once in this thread).
 
 
 

"white" LED's vs. incandescent and halogen lights

Post by Clive Georg » Wed, 16 Dec 2009 05:59:50


Quote:






>>>>> That's the crux of the problem. Rectifying the AC to DC, filtering it,
>>>>> and regulating the voltage or current, isn't difficult or expensive,
>>>>> but there's a big penalty in terms of efficiency, and you can't afford
>>>>> those efficiency losses with a dynamo.
>>>> Care to quantify "big penalty"? Coz LED dynamo lights are out there,
>>>> front and rear, and are darned bright.
>>> Can you quantify "darned bright" first?

>> Stop ducking the question in the manner of a 5-year-old in a school
>> playground.

> LOL, so I guess you can't quantify "darned bright" huh?

> The loss of efficiency in rectification and regulation has been explained
> here numerous times. I'm sure you can google it. Unlike "darned bright"
> the loss of efficiency is an actual quantifiable number based on the
> buck-boost regulator efficiency and the efficiency of a full wave bridge
> rectifier.

> Even at the maximum theoretical efficiencies you're still at only xx%
> (your homework is to Google the maximum efficiency of a buck boost
> switching regulator, and a bridge rectifier and multiply the two numbers
> together).

No, that's your job. Remember, you're the one who said "big penalty".

You might also want to consider the bit of my post you snipped.

 
 
 

"white" LED's vs. incandescent and halogen lights

Post by N8N » Wed, 16 Dec 2009 06:16:14

On Dec 14, 3:23?pm, "Just zis Guy, you know?"

Quote:



> >LOL, I was referring to the dynamos sold by Peter White, not the ones
> >sold by Yellow Jersey 37 years ago.

> http://www.simpsoncycles.co.uk/product.php?xProd=1937

> 34.99 (under 60 of your colonial dollars). I have one, it works
> flawlessly and will comfortably power a B&M IQ Cyo which produces 60
> Lux, which is five times the German legal required light output.

And that's how much with shipping?

AFAICT, the best deal going in the US is the prebuilt VO front wheel
at about $120ish - I bought one.  Unfortunately, the CR18 rear wheels
have been unavailable for months - I suspect that they may be
discontinuing them? - so the screaming dealness of the front wheel was
offset by the cost of having a rear wheel built at my LBS :(

nate

 
 
 

"white" LED's vs. incandescent and halogen lights

Post by Just zis Guy, you know » Wed, 16 Dec 2009 06:34:34



Quote:
>> 34.99 (under 60 of your colonial dollars). I have one, it works
>> flawlessly and will comfortably power a B&M IQ Cyo which produces 60
>> Lux, which is five times the German legal required light output.

>And that's how much with shipping?

34.99.  Free delivery.

Guy
--
http://www.chapmancentral.co.uk/urc
GPG public key at http://www.chapmancentral.co.uk/pgp-public-key.txt

 
 
 

"white" LED's vs. incandescent and halogen lights

Post by N8N » Wed, 16 Dec 2009 06:38:46

On Dec 14, 4:34?pm, "Just zis Guy, you know?"

Quote:



> >> 34.99 (under 60 of your colonial dollars). I have one, it works
> >> flawlessly and will comfortably power a B&M IQ Cyo which produces 60
> >> Lux, which is five times the German legal required light output.

> >And that's how much with shipping?

> 34.99. ?Free delivery.

To the YooEss?  I kinda doubt it...  Even Wiggle doesn't give free
shipping under about $80ish, and I can't see how they are making money
on orders at that level.

nate

 
 
 

"white" LED's vs. incandescent and halogen lights

Post by SMS » Wed, 16 Dec 2009 06:47:00

Quote:

> AFAICT, the best deal going in the US is the prebuilt VO front wheel
> at about $120ish - I bought one.  Unfortunately, the CR18 rear wheels
> have been unavailable for months - I suspect that they may be
> discontinuing them? - so the screaming dealness of the front wheel was
> offset by the cost of having a rear wheel built at my LBS :(

LOL, so it's $60 was just for a hub dynamo without the wheel? How much
is a whole wheel? Peter White charges quite a bit for his custom wheels
with a dynohub, OTOH the VO wheel is a pretty good deal at $120,
"http://www.velo-orange.com/vopbprimwnoh.html." I'm going to pick one up
for my touring bike.
 
 
 

"white" LED's vs. incandescent and halogen lights

Post by Just zis Guy, you know » Wed, 16 Dec 2009 06:48:37



Quote:
>> >> 34.99 (under 60 of your colonial dollars). I have one, it works
>> >> flawlessly and will comfortably power a B&M IQ Cyo which produces 60
>> >> Lux, which is five times the German legal required light output.
>> >And that's how much with shipping?
>> 34.99. Free delivery.
>To the YooEss?  I kinda doubt it...  Even Wiggle doesn't give free
>shipping under about $80ish, and I can't see how they are making money
>on orders at that level.

That's a UK site, I have no idea how much the same unit would cost
from a US shop but I can't recall ever having found any Japanese
manufactured item cheaper in the UK than in the US - usually it's very
much the other way around. Not to say it wouldn't happen, it would
just be unusual for it to be cheaper here than there.

Guy
--
http://www.chapmancentral.co.uk/urc
GPG public key at http://www.chapmancentral.co.uk/pgp-public-key.txt

 
 
 

"white" LED's vs. incandescent and halogen lights

Post by Just zis Guy, you know » Wed, 16 Dec 2009 07:28:12



Quote:
> $60 was just for a hub dynamo without the wheel? How much
>is a whole wheel?

I don't know about you but I usually buy my bikes with a front wheel
(eccentric, I know).  The Brompton was ordered with a SON on the
front, no charge was made for the build.  My last wheel build cost me
20, IIRC, but some people roll their own.

What you're missing here is that dynamo lighting is always on the
bike, a low theft risk in itself, and has a very long service life
often with close to zero maintenance.  

Put it another way: how many cars require you to remember to recharge
the lights every night, or replace batteries every few weeks?  

If you use a bike as a commuting vehicle then permanently fitted
always available lights make great sense, which is presumably why they
are so popular in Europe.

Guy
--
http://www.chapmancentral.co.uk/urc
GPG public key at http://www.chapmancentral.co.uk/pgp-public-key.txt

 
 
 

"white" LED's vs. incandescent and halogen lights

Post by Nate Nage » Wed, 16 Dec 2009 11:17:55

Quote:


>> AFAICT, the best deal going in the US is the prebuilt VO front wheel
>> at about $120ish - I bought one.  Unfortunately, the CR18 rear wheels
>> have been unavailable for months - I suspect that they may be
>> discontinuing them? - so the screaming dealness of the front wheel was
>> offset by the cost of having a rear wheel built at my LBS :(

> LOL, so it's $60 was just for a hub dynamo without the wheel? How much
> is a whole wheel? Peter White charges quite a bit for his custom wheels
> with a dynohub, OTOH the VO wheel is a pretty good deal at $120,
> "http://www.velo-orange.com/vopbprimwnoh.html." I'm going to pick one up
> for my touring bike.

To be fair to Peter (and my LBS as well) the VO wheels use straight
gauge spokes, while I believe both Peter and my LBS use double-butted.
But if it's an issue, I'll address it when it occurs and not worry about
it in the meantime.

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

 
 
 

"white" LED's vs. incandescent and halogen lights

Post by Nate Nage » Wed, 16 Dec 2009 11:19:44


Quote:


>>>>> 34.99 (under 60 of your colonial dollars). I have one, it works
>>>>> flawlessly and will comfortably power a B&M IQ Cyo which produces 60
>>>>> Lux, which is five times the German legal required light output.
>>>> And that's how much with shipping?
>>> 34.99.  Free delivery.
>> To the YooEss?  I kinda doubt it...  Even Wiggle doesn't give free
>> shipping under about $80ish, and I can't see how they are making money
>> on orders at that level.

> That's a UK site, I have no idea how much the same unit would cost
> from a US shop but I can't recall ever having found any Japanese
> manufactured item cheaper in the UK than in the US - usually it's very
> much the other way around. Not to say it wouldn't happen, it would
> just be unusual for it to be cheaper here than there.

> Guy

I believe that that is in fact the case, likely because hub dynamos just
haven't got a whole lot of traction over here for some reason.  Dunno
why; they're kinda cool.  Guess they're not "racy" enough though.

nate

--
replace "roosters" with "cox" to reply.
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