On Thu, 11 Aug 2016 09:30:00 +0100, The Natural Philosopher
wrote:


I remember seeing some dynamo systems which had a battery container
attached to the frame. The advantage of batteries was that when you
stopped moving - eg at traffic lights, your cycle lights stayed on. But
nowadays cyclists never seem to stop for traffic lights, so behaps a
back-up battery isn't needed. ;=)

Yep. pack of nicads clamped to the vertical tube under the saddle and a
hub dynamo.

Long time ago that was.

My other had a back up system on her Dawes bike back in the forties,
apparently quite an upmarket option back then. There was no charging
involved , I don't actually know if the set up switched automatically
to the dry batteries which would have been the std zinc carbon or if
it had to be done manually by a selector switch as a approached an
area that stopping was to be anticipated.

G.Harman

wrote:


I can't imagine any scenario where a dynamo makes more sense than a rechargeable battery.

Then you are a man of very little imagination.

Tim

--
Trolls and troll feeders go in my killfile

On Thursday, 11 August 2016 08:58:59 UTC+1, harry wrote:
On Wednesday, 10 August 2016 11:46:05 UTC+1, David wrote:
The standard ways a

a hub dynamo (ridiculously expensive considering I had one on my bike in
the 1960s) but this needs a wheel rebuild as well as the purchase of the
hub.

a bottle dynamo (which is a pain to get to rub against the tyre when you
want it to and not when you don't). Also noisy and perhaps not very
efficient.

There was a dynamo a while back which fitted to the frame just in front of
the rear wheel and contacted the tread of the tyre instead of the side
wall but I haven't seen this around for a while. Cant locate it via Google
after a quick search.

I did wonder if there was another way. For example using a disc brake like
assembly, with a metal plate rotating through two fixed contacts (just
like a disc brake and pads).

For another example, having a light metal cover on the front wheel (like
the aero wheels on time trial bikes) and fixed contacts all the way up the
front forks.

Both (badly described) methods should provide the basic rotating split
ring and metal brushes of a DC generator. I just have no idea how
efficient this would be compared to a hub or bottle generator.

Of course, an adverse reaction to water and grit might play a part as well.




Bicycle generators are all AC.
Why would they need to be DC?
Have you never dismantled one?

Because LEDs run on DC not AC like filiment bulds so you'd be wasting half a cycle (dont forget it's a Bi-cycle) to only rectifcy half the wave.

But I still see little point in it.

be fun to put a wind turbine on the back and a solar panel.

But I;m not sure how effcient a dynmo is I've heard most aren't

I don't remmeber pro cyclist using them in compitition or for anything.

On 11/08/2016 13:50, whisky-dave wrote:

But I;m not sure how effcient a dynmo is I've heard most aren't

Hub dynamos aren't noticable in normal use.

I don't remmeber pro cyclist using them in compitition or for anything.

There is a weight penalty, and a small power penalty (under a watt) when
off and obviously a few watts when on. Racers don't use any lights, so
why take that hit?

However they are popular for the long distance audax rides which aren't
races, but do include eg paris-brest-paris which is 1200km in 4 days.

The Natural Philosopher wrote:
On 11/08/16 10:48, Syd Rumpo wrote:
On 11/08/2016 10:15, Theo wrote:
NY wrote:
Do modern dynamos that can power USB devices still generate AC, or do
they
have the commutator rings wired to reverse the phase of the negative
cycles
to give full-wave rectification? I suppose it's about as easy to
modify the
generator as it is to add a couple of extra diodes as part of all the
other
electronics needed to provide a smoothed and regulated 5V for USB,
together
with a bit of storage in a battery to cover times when you are going
slower
or when you stop at lights.

I haven't seen the USB kind, but it seems unlikely they would make big
changes to the dynamo mechanics based on the application when they
could
send a few pennies on some diodes. The standard lighting systems (be
they
hub or bottle) are all AC, with diodes inside the LED lamps to
rectify. It
would be quite a bit of effort to make a non-standard system. Most
are 6v
but there are some 12v systems around. I suspect most of the goal
is USB
charging rather than USB power, so it's expected that cutouts will
happen
from time to time.

Theo

Make your bridge rectifier out of LEDs.

Not a great idea. They are not designed to take much reverse voltage.

I think the reverse breakdown is around 5V.

What I would do for a quality bike light solution is first of all
select a rugged rechargeable. LiFePO or NiCd.

Then get some kind of hub based alternator featuring Neodymium
magnets and as lot of iron and copper with a bridge rectifier and some
seriously large capacitor to drive a smart inverter that would provide
a stabilised battery charge and light driving circuit coupled to some
decent high intensity LEDS with or without strobing.

Normal day riding would recharge the battery, and at night one would
hope that the alternator would be enough to at least drive the lights
except when stopped.




Cheers



Too inefficient, the forward volt drop is well over 1V can be as
high as 3V I believe.

On Thursday, 11 August 2016 16:55:34 UTC+1, Capitol wrote:
The Natural Philosopher wrote:
On 11/08/16 10:48, Syd Rumpo wrote:
On 11/08/2016 10:15, Theo wrote:
NY wrote:
Do modern dynamos that can power USB devices still generate AC, or do
they
have the commutator rings wired to reverse the phase of the negative
cycles
to give full-wave rectification? I suppose it's about as easy to
modify the
generator as it is to add a couple of extra diodes as part of all the
other
electronics needed to provide a smoothed and regulated 5V for USB,
together
with a bit of storage in a battery to cover times when you are going
slower
or when you stop at lights.

I haven't seen the USB kind, but it seems unlikely they would make big
changes to the dynamo mechanics based on the application when they
could
send a few pennies on some diodes. The standard lighting systems (be
they
hub or bottle) are all AC, with diodes inside the LED lamps to
rectify. It
would be quite a bit of effort to make a non-standard system. Most
are 6v
but there are some 12v systems around. I suspect most of the goal
is USB
charging rather than USB power, so it's expected that cutouts will
happen
from time to time.

Theo

Make your bridge rectifier out of LEDs.

Not a great idea. They are not designed to take much reverse voltage.

I think the reverse breakdown is around 5V.

What I would do for a quality bike light solution is first of all
select a rugged rechargeable. LiFePO or NiCd.

Then get some kind of hub based alternator featuring Neodymium
magnets and as lot of iron and copper with a bridge rectifier and some
seriously large capacitor to drive a smart inverter that would provide
a stabilised battery charge and light driving circuit coupled to some
decent high intensity LEDS with or without strobing.

Normal day riding would recharge the battery, and at night one would
hope that the alternator would be enough to at least drive the lights
except when stopped.




Cheers



Too inefficient, the forward volt drop is well over 1V can be as
high as 3V I believe.

FETs might make it viable energy-wise, they can rectify with minimal loss.


NT

On Thursday, 11 August 2016 09:12:02 UTC+1, NY wrote:
"harry" wrote in message
...
Bicycle generators are all AC.
Why would they need to be DC?
Have you never dismantled one?

I'd never thought about this. For lighting it doesn't matter at all whether
you generate AC or DC - it's only when you need to power electronic
equipment (eg USB charger) that you need some form of rectification and
smoothing.

Do modern dynamos that can power USB devices still generate AC, or do they
have the commutator rings wired to reverse the phase of the negative cycles
to give full-wave rectification? I suppose it's about as easy to modify the
generator as it is to add a couple of extra diodes as part of all the other
electronics needed to provide a smoothed and regulated 5V for USB, together
with a bit of storage in a battery to cover times when you are going slower
or when you stop at lights.

A commutator (and brushes) is just a mechanical rectifier.
Nobodies going to bother with such a thing when electronic diodes are available.
The traditional "dynamos" were all in fact alternators.
Just a permanent magnet rotating inside a coil.

The only reason you might need DC for is to charge a battery.
Or a capacitor these days.
Or maybe for LEDs. But that can be got round.
I'd have thought LEDs drew so little current that (rechargeable) batteries would not be a problem.
My LED torch batteries seem to last almost forever.

On 11/08/2016 09:12, NY wrote:
"harry" wrote in message
...
Bicycle generators are all AC.
Why would they need to be DC?
Have you never dismantled one?

I'd never thought about this. For lighting it doesn't matter at all
whether you generate AC or DC - it's only when you need to power
electronic equipment (eg USB charger) that you need some form of
rectification and smoothing.

Do modern dynamos that can power USB devices still generate AC, or do
they have the commutator rings wired to reverse the phase of the
negative cycles to give full-wave rectification? I suppose it's about as
easy to modify the generator as it is to add a couple of extra diodes as
part of all the other electronics needed to provide a smoothed and
regulated 5V for USB, together with a bit of storage in a battery to
cover times when you are going slower or when you stop at lights.

I would put moving magnets inside fixed coils and have no commutators.

The Natural Philosopher Wrote in message:
On 11/08/16 09:20, charles wrote:
In article , NY
wrote:
"harry" wrote in message
...
Bicycle generators are all AC. Why would they need to be DC? Have you
never dismantled one?

I'd never thought about this. For lighting it doesn't matter at all
whether you generate AC or DC - it's only when you need to power
electronic equipment (eg USB charger) that you need some form of
rectification and smoothing.

Do modern dynamos that can power USB devices still generate AC, or do
they have the commutator rings wired to reverse the phase of the
negative cycles to give full-wave rectification? I suppose it's about as
easy to modify the generator as it is to add a couple of extra diodes as
part of all the other electronics needed to provide a smoothed and
regulated 5V for USB, together with a bit of storage in a battery to
cover times when you are going slower or when you stop at lights.

I remember seeing some dynamo systems which had a battery container
attached to the frame. The advantage of batteries was that when you
stopped moving - eg at traffic lights, your cycle lights stayed on. But
nowadays cyclists never seem to stop for traffic lights, so behaps a
back-up battery isn't needed. ;=)

Yep. pack of nicads clamped to the vertical tube under the saddle and a
hub dynamo.

Long time ago that was.


Modern LED lights usually have a built in capacitor to power the
light when stopped for a few minutes.

Tehy are also brighter than the old lamps. We still have a bike
here with an old Halogen light on, it was considered a decent
lamp back in the day. It doesn't really get used at night and so
have not bothered to swap it yet, used it a few months back and
the light now seems rubbish compared to the dynamo powered LED
lamp on my bike

Clive George Wrote in message:
On 11/08/2016 13:50, whisky-dave wrote:

But I;m not sure how effcient a dynmo is I've heard most aren't

Hub dynamos aren't noticable in normal use.

I don't remmeber pro cyclist using them in compitition or for anything.

There is a weight penalty, and a small power penalty (under a watt) when
off and obviously a few watts when on. Racers don't use any lights, so
why take that hit?


Quite, they don't use panniers either and lots of other useful
things :-)

Old bottle dynamos, even good ones are quite noticeable in use
(not just the noise, but stop pedaling and you can see how much
quicker the bikes stops, you can't tell if a lamp powered by hub
dynamo is on or not from the difference it makes to the
cycling.



--
--
Chris French

In article ,
Chris French wrote:
There is a weight penalty, and a small power penalty (under a watt)
when off and obviously a few watts when on. Racers don't use any
lights, so why take that hit?


Quite, they don't use panniers either and lots of other useful
things :-)

Old bottle dynamos, even good ones are quite noticeable in use
(not just the noise, but stop pedaling and you can see how much
quicker the bikes stops, you can't tell if a lamp powered by hub
dynamo is on or not from the difference it makes to the
cycling.

Yup. Although the bottle type tended to give a brighter light in the days
when I cycled. But a friction drive is horribly inefficient.

--
*When chemists die, they barium.*

Dave Plowman London SW
To e-mail, change noise into sound.

On 11/08/2016 16:55, Capitol wrote:

Then get some kind of hub based alternator featuring Neodymium
magnets and as lot of iron and copper with a bridge rectifier and some
seriously large capacitor to drive a smart inverter that would provide
a stabilised battery charge and light driving circuit coupled to some
decent high intensity LEDS with or without strobing.

Normal day riding would recharge the battery, and at night one would
hope that the alternator would be enough to at least drive the lights
except when stopped.

Too inefficient, the forward volt drop is well over 1V can be as
high as 3V I believe.

The generators on bike lights are slightly more complicated. They're
designed to current limit, which means you get 0.5A or so at most speeds
- but if you increase the resistance, you get more than 6v. So 3V volt
drop isn't necessarily that big a deal - though I'd try a bit harder.

What TNP is describing is close to what people use in real life - though
the battery backup isn't needed, it's just a capacitor.

On 11/08/2016 23:29, Dave Plowman (News) wrote:
In article ,
Chris French wrote:
There is a weight penalty, and a small power penalty (under a watt)
when off and obviously a few watts when on. Racers don't use any
lights, so why take that hit?


Quite, they don't use panniers either and lots of other useful
things :-)

Old bottle dynamos, even good ones are quite noticeable in use
(not just the noise, but stop pedaling and you can see how much
quicker the bikes stops, you can't tell if a lamp powered by hub
dynamo is on or not from the difference it makes to the
cycling.

Yup. Although the bottle type tended to give a brighter light in the days
when I cycled. But a friction drive is horribly inefficient.

Sturmey hub vs other bottle? Yes, the sturmey hub wasn't very powerful -
the wheel turns quite slowly, so the magnets required weren't available
(or at least not at a sane price) back then. The modern hub dynamos give
rather more.

On 12/08/16 00:19, Clive George wrote:
On 11/08/2016 16:55, Capitol wrote:

Then get some kind of hub based alternator featuring Neodymium
magnets and as lot of iron and copper with a bridge rectifier and some
seriously large capacitor to drive a smart inverter that would provide
a stabilised battery charge and light driving circuit coupled to some
decent high intensity LEDS with or without strobing.

Normal day riding would recharge the battery, and at night one would
hope that the alternator would be enough to at least drive the lights
except when stopped.

Too inefficient, the forward volt drop is well over 1V can be as
high as 3V I believe.

The generators on bike lights are slightly more complicated. They're
designed to current limit, which means you get 0.5A or so at most speeds
- but if you increase the resistance, you get more than 6v. So 3V volt
drop isn't necessarily that big a deal - though I'd try a bit harder.

What TNP is describing is close to what people use in real life - though
the battery backup isn't needed, it's just a capacitor.

These days the line between a battery and a supercapacitor is
increasingly blurred.



--
If you tell a lie big enough and keep repeating it, people will
eventually come to believe it. The lie can be maintained only for such
time as the State can shield the people from the political, economic
and/or military consequences of the lie. It thus becomes vitally
important for the State to use all of its powers to repress dissent, for
the truth is the mortal enemy of the lie, and thus by extension, the
truth is the greatest enemy of the State.

Joseph Goebbels

In article ,
Clive George wrote:
Yup. Although the bottle type tended to give a brighter light in the
days when I cycled. But a friction drive is horribly inefficient.

Sturmey hub vs other bottle? Yes, the sturmey hub wasn't very powerful -
the wheel turns quite slowly, so the magnets required weren't available
(or at least not at a sane price) back then. The modern hub dynamos give
rather more.

That certainly makes sense. Modern low voltage DC motors have also been
improved out of all recognition by better magnets.

--
*Tell me to 'stuff it' - I'm a taxidermist.

Dave Plowman London SW
To e-mail, change noise into sound.

On Wed, 10 Aug 2016 18:43:23 +0100, Clive George wrote:

On 10/08/2016 18:19, David wrote:
On Wed, 10 Aug 2016 13:00:17 +0100, Clive George wrote:

On 10/08/2016 11:46, David wrote:
The standard ways a

a hub dynamo (ridiculously expensive considering I had one on my bike
in the 1960s) but this needs a wheel rebuild as well as the purchase
of the hub.

Is the right answer though.

The posh ones are expensive, but Shimano make some which are very
sanely priced.

http://www.bike-discount.de/en/shop/hub-dynamo-8865

20 euro. I wouldn't rebuild the wheel, as you'll need new spokes
anyway,
so factor in new spokes (16 quid from chain reaction) and rim (15 quid
or so?).

It'll give you the most reliable electricity supply on a bike. Pretty
much unnoticable when on too, unlike a bottle or a bottom bracket
generator. (the bottom bracket ones suffered from being in the worst
place for muck on a bike).

Apart from the question "why would I need a new rim" that sounds
sensible.
I can see that new spokes would be needed.

Because new rims aren't that expensive and it leaves you a complete
spare wheel.

However there is one minor issue - I was considering it for my Dutch
bike which has hub gears and brake at the rear, a hub brake at the
front, and so nowhere to fit a hub dynamo.

Which made me ponder.

Dyno-hubs are common on dutch bikes, complete with hub brakes :-)

http://www.ebay.co.uk/itm/Taylor-Whe...wheel-ZAC2000-
with-hub-dynamo-DH-3R35-silver-/231103011081?_trksid=p2141725.m3641.l6368

(they'll do a 28"/700c one too, you'll just need to look)

What sort of hub brake do you have?

Shimano Nexus with a bloody big lump of iron into a bracket on the frame
to stop it rotating.

I did look glancingly at the Shimano price for a combined dynamo and
brake, if I remember correctly, but I also seem to remember having to go
and lie down somewhere quiet for a bit afterwards.

Cheers


Dave R



--
Windows 8.1 on PCSpecialist box

On Thu, 11 Aug 2016 09:20:09 +0100, charles wrote:

In article , NY
wrote:
"harry" wrote in message
...
Bicycle generators are all AC. Why would they need to be DC? Have you
never dismantled one?

I'd never thought about this. For lighting it doesn't matter at all
whether you generate AC or DC - it's only when you need to power
electronic equipment (eg USB charger) that you need some form of
rectification and smoothing.

Do modern dynamos that can power USB devices still generate AC, or do
they have the commutator rings wired to reverse the phase of the
negative cycles to give full-wave rectification? I suppose it's about
as easy to modify the generator as it is to add a couple of extra
diodes as part of all the other electronics needed to provide a
smoothed and regulated 5V for USB, together with a bit of storage in a
battery to cover times when you are going slower or when you stop at
lights.

I remember seeing some dynamo systems which had a battery container
attached to the frame. The advantage of batteries was that when you
stopped moving - eg at traffic lights, your cycle lights stayed on. But
nowadays cyclists never seem to stop for traffic lights, so behaps a
back-up battery isn't needed. ;=)

I had one on my bike in the early to mid sixties (which also had a hub
dynamo). Alloy tube which held about three U2 batteries (whatever they are
called now). The headlight had a 3 position switch underneath; on, off,
battery.

Cheers


Dave R



--
Windows 8.1 on PCSpecialist box

On Friday, 12 August 2016 19:20:01 UTC+1, David wrote:
On Thu, 11 Aug 2016 09:20:09 +0100, charles wrote:

In article , NY
wrote:
"harry" wrote in message
...
Bicycle generators are all AC. Why would they need to be DC? Have you
never dismantled one?

I'd never thought about this. For lighting it doesn't matter at all
whether you generate AC or DC - it's only when you need to power
electronic equipment (eg USB charger) that you need some form of
rectification and smoothing.

Do modern dynamos that can power USB devices still generate AC, or do
they have the commutator rings wired to reverse the phase of the
negative cycles to give full-wave rectification? I suppose it's about
as easy to modify the generator as it is to add a couple of extra
diodes as part of all the other electronics needed to provide a
smoothed and regulated 5V for USB, together with a bit of storage in a
battery to cover times when you are going slower or when you stop at
lights.

I remember seeing some dynamo systems which had a battery container
attached to the frame. The advantage of batteries was that when you
stopped moving - eg at traffic lights, your cycle lights stayed on. But
nowadays cyclists never seem to stop for traffic lights, so behaps a
back-up battery isn't needed. ;=)

I had one on my bike in the early to mid sixties (which also had a hub
dynamo). Alloy tube which held about three U2 batteries (whatever they are
called now). The headlight had a 3 position switch underneath; on, off,
battery.

But not recharging the battery.

On Friday, 12 August 2016 10:24:48 UTC+1, Dave Plowman (News) wrote:
In article ,
Clive George wrote:
Yup. Although the bottle type tended to give a brighter light in the
days when I cycled. But a friction drive is horribly inefficient.

Sturmey hub vs other bottle? Yes, the sturmey hub wasn't very powerful -
the wheel turns quite slowly, so the magnets required weren't available
(or at least not at a sane price) back then. The modern hub dynamos give
rather more.

That certainly makes sense. Modern low voltage DC motors have also been
improved out of all recognition by better magnets.

There is no such thing as a DC motor.
I've told you before.

In article ,
harry wrote:
On Friday, 12 August 2016 10:24:48 UTC+1, Dave Plowman (News) wrote:
In article ,
Clive George wrote:
Yup. Although the bottle type tended to give a brighter light in the
days when I cycled. But a friction drive is horribly inefficient.

Sturmey hub vs other bottle? Yes, the sturmey hub wasn't very
powerful - the wheel turns quite slowly, so the magnets required
weren't available (or at least not at a sane price) back then. The
modern hub dynamos give rather more.

That certainly makes sense. Modern low voltage DC motors have also been
improved out of all recognition by better magnets.

There is no such thing as a DC motor.
I've told you before.

does that mean that those hand held fans run from a battery need an
inverter to work? I think not. And I'm sure the starter motot in my car
runs on DC.

--
from KT24 in Surrey, England

On 10/08/2016 21:38, Clive George wrote:
On 10/08/2016 20:56, wrote:

I can't imagine any scenario where a dynamo makes more sense than a
rechargeable battery.

Any bike used regularly at night. The light is always there, ready, no
need to remember to carry anything, charge anything. You wouldn't put up
with having to carry a car battery in to charge every day - why do so on
a bike?


I use cheap but bright LEDs, screwed to the frame. Used all through last
winter more or less daily (so 2 hours/week) on the same set of AAA
batteries.

I do have one of those super-bright LED front lamps for the rare
occasions I'm cycling on unlit roads.

--
Cheers, Rob

On 13/08/2016 06:55, harry wrote:
On Friday, 12 August 2016 10:24:48 UTC+1, Dave Plowman (News) wrote:
In article ,
Clive George wrote:
Yup. Although the bottle type tended to give a brighter light in the
days when I cycled. But a friction drive is horribly inefficient.

Sturmey hub vs other bottle? Yes, the sturmey hub wasn't very powerful -
the wheel turns quite slowly, so the magnets required weren't available
(or at least not at a sane price) back then. The modern hub dynamos give
rather more.

That certainly makes sense. Modern low voltage DC motors have also been
improved out of all recognition by better magnets.

There is no such thing as a DC motor.
I've told you before.

So what type of voltage do you apply to a "low voltage DC motor"?

On 13/08/2016 08:17, charles wrote:
In article ,
harry wrote:
On Friday, 12 August 2016 10:24:48 UTC+1, Dave Plowman (News) wrote:
In article ,
Clive George wrote:
Yup. Although the bottle type tended to give a brighter light in the
days when I cycled. But a friction drive is horribly inefficient.

Sturmey hub vs other bottle? Yes, the sturmey hub wasn't very
powerful - the wheel turns quite slowly, so the magnets required
weren't available (or at least not at a sane price) back then. The
modern hub dynamos give rather more.

That certainly makes sense. Modern low voltage DC motors have also been
improved out of all recognition by better magnets.

There is no such thing as a DC motor.
I've told you before.

does that mean that those hand held fans run from a battery need an
inverter to work? I think not. And I'm sure the starter motot in my car
runs on DC.

Every so often Harry like to show prowess in his greater
misunderstanding. I'm surprised he didn't join the argument about
centrifugal and centripetal forces.

The general definition of a DC motor is one that you apply DC to. Of
course there is also the unipolar motor!

In article ,
harry wrote:

There is no such thing as a DC motor.
I've told you before.

Yes there is. You are probably confusing something you read with reality.

Cheers
--
Syd

On 13/08/2016 10:55, Tim Streater wrote:
In article , Fredxxx
wrote:

On 13/08/2016 08:17, charles wrote:
In article ,
harry wrote:
On Friday, 12 August 2016 10:24:48 UTC+1, Dave Plowman (News) wrote:
In article ,
Clive George wrote:
Yup. Although the bottle type tended to give a brighter light in the
days when I cycled. But a friction drive is horribly inefficient.

Sturmey hub vs other bottle? Yes, the sturmey hub wasn't very
powerful - the wheel turns quite slowly, so the magnets required
weren't available (or at least not at a sane price) back then. The
modern hub dynamos give rather more.

That certainly makes sense. Modern low voltage DC motors have also
been
improved out of all recognition by better magnets.

There is no such thing as a DC motor.
I've told you before.

does that mean that those hand held fans run from a battery need an
inverter to work? I think not. And I'm sure the starter motot in my car
runs on DC.

Every so often Harry like to show prowess in his greater
misunderstanding. I'm surprised he didn't join the argument about
centrifugal and centripetal forces.

The general definition of a DC motor is one that you apply DC to. Of
course there is also the unipolar motor!

Does that run on magnetic monopoles?

No, homopoles!
https://en.wikipedia.org/wiki/Homopolar_motor
https://en.wikipedia.org/wiki/Unipolar_motor

On Sat, 13 Aug 2016 10:49:29 +0100, Syd Rumpo wrote:

In article ,
harry wrote:

There is no such thing as a DC motor.
I've told you before.

Yes there is. You are probably confusing something you read with
reality.

He's obviously oblivious to the concept of the homopolar motor, a true
DC electric motor so well described he-

https://en.wikipedia.org/wiki/Homopolar_motor

--
Johnny B Good

On Saturday, 13 August 2016 08:18:46 UTC+1, charles wrote:
In article ,
harry wrote:
On Friday, 12 August 2016 10:24:48 UTC+1, Dave Plowman (News) wrote:
In article ,
Clive George wrote:
Yup. Although the bottle type tended to give a brighter light in the
days when I cycled. But a friction drive is horribly inefficient.

Sturmey hub vs other bottle? Yes, the sturmey hub wasn't very
powerful - the wheel turns quite slowly, so the magnets required
weren't available (or at least not at a sane price) back then. The
modern hub dynamos give rather more.

That certainly makes sense. Modern low voltage DC motors have also been
improved out of all recognition by better magnets.

There is no such thing as a DC motor.
I've told you before.

does that mean that those hand held fans run from a battery need an
inverter to work? I think not. And I'm sure the starter motot in my car
runs on DC.


No it runs on AC.
The "commutator and brushes" are a mechanical inverter.

These are expensive and wear out so these days it's replaced with electronics to turn DC to AC where ever possible.

On Saturday, 13 August 2016 15:21:15 UTC+1, Johnny B Good wrote:
On Sat, 13 Aug 2016 10:49:29 +0100, Syd Rumpo wrote:

In article ,
harry wrote:

There is no such thing as a DC motor.
I've told you before.

Yes there is. You are probably confusing something you read with
reality.

He's obviously oblivious to the concept of the homopolar motor, a true
DC electric motor so well described he-

https://en.wikipedia.org/wiki/Homopolar_motor

--
Johnny B Good

A laboratory device of little/no practical use.
There's one he-
https://www.youtube.com/watch?v=xbCN3EnYfWU
Doesn't it look useful?

In message ,
harry writes
On Saturday, 13 August 2016 08:18:46 UTC+1, charles wrote:
In article ,
harry wrote:
On Friday, 12 August 2016 10:24:48 UTC+1, Dave Plowman (News) wrote:
In article ,
Clive George wrote:
Yup. Although the bottle type tended to give a brighter light in the
days when I cycled. But a friction drive is horribly inefficient.

Sturmey hub vs other bottle? Yes, the sturmey hub wasn't very
powerful - the wheel turns quite slowly, so the magnets required
weren't available (or at least not at a sane price) back then. The
modern hub dynamos give rather more.

That certainly makes sense. Modern low voltage DC motors have also been
improved out of all recognition by better magnets.

There is no such thing as a DC motor.
I've told you before.

does that mean that those hand held fans run from a battery need an
inverter to work? I think not. And I'm sure the starter motot in my car
runs on DC.


No it runs on AC.
The "commutator and brushes" are a mechanical inverter.

These are expensive and wear out so these days it's replaced with
electronics to turn DC to AC where ever possible.

Hmm.. suppose the commutator is simply switching the current to a
different winding on the armature? Direction of flow may not change
which appears to me to be DC.

--
Tim Lamb

On 13/08/2016 18:00, harry wrote:
On Saturday, 13 August 2016 15:21:15 UTC+1, Johnny B Good wrote:
On Sat, 13 Aug 2016 10:49:29 +0100, Syd Rumpo wrote:

In article ,
harry wrote:

There is no such thing as a DC motor.
I've told you before.

Yes there is. You are probably confusing something you read with
reality.

He's obviously oblivious to the concept of the homopolar motor, a true
DC electric motor so well described he-

https://en.wikipedia.org/wiki/Homopolar_motor

--
Johnny B Good

A laboratory device of little/no practical use.
There's one he-
https://www.youtube.com/watch?v=xbCN3EnYfWU
Doesn't it look useful?

I can't believe how ignorant you are, from:
https://en.wikipedia.org/wiki/Homopolar_motor
"B. G. Lamme described in 1912 a homopolar machine rated 2,000 kW, 260
V, 7,700 A and 1,200 rpm with 16 slip rings operating at a peripheral
velocity of 67 m/s. A unipolar generator rated 1,125 kW, 7.5 V 150,000
A, 514 rpm built in 1934 was installed in a U.S. steel mill for pipe
welding purposes."

If you think you can wriggle out of claiming a DC motor isn't a DC
motor, and then claim a unipolar device has no practical use you should
consider seeing your doctor or simply stop spouting your ignorance on
subjects you know nothing about.

On 13/08/2016 17:56, harry wrote:
On Saturday, 13 August 2016 08:18:46 UTC+1, charles wrote:
In article ,
harry wrote:
On Friday, 12 August 2016 10:24:48 UTC+1, Dave Plowman (News) wrote:
In article ,
Clive George wrote:
Yup. Although the bottle type tended to give a brighter light in the
days when I cycled. But a friction drive is horribly inefficient.

Sturmey hub vs other bottle? Yes, the sturmey hub wasn't very
powerful - the wheel turns quite slowly, so the magnets required
weren't available (or at least not at a sane price) back then. The
modern hub dynamos give rather more.

That certainly makes sense. Modern low voltage DC motors have also been
improved out of all recognition by better magnets.

There is no such thing as a DC motor.
I've told you before.

does that mean that those hand held fans run from a battery need an
inverter to work? I think not. And I'm sure the starter motot in my car
runs on DC.


No it runs on AC.
The "commutator and brushes" are a mechanical inverter.

driven by DC and hence called a DC motor.
https://en.wikipedia.org/wiki/DC_motor

You can deny "A DC motor is any of a class of electrical machines that
converts direct current electrical power into mechanical power" but to
do so only emphasises your ignorance.

These are expensive and wear out so these days it's replaced with electronics to turn DC to AC where ever possible.

Care to give examples of car starter motors that don't use brushes?

On Sunday, 14 August 2016 01:34:56 UTC+1, Fredxxx wrote:
On 13/08/2016 18:00, harry wrote:
On Saturday, 13 August 2016 15:21:15 UTC+1, Johnny B Good wrote:
On Sat, 13 Aug 2016 10:49:29 +0100, Syd Rumpo wrote:

In article ,
harry wrote:

There is no such thing as a DC motor.
I've told you before.

Yes there is. You are probably confusing something you read with
reality.

He's obviously oblivious to the concept of the homopolar motor, a true
DC electric motor so well described he-

https://en.wikipedia.org/wiki/Homopolar_motor

--
Johnny B Good

A laboratory device of little/no practical use.
There's one he-
https://www.youtube.com/watch?v=xbCN3EnYfWU
Doesn't it look useful?

I can't believe how ignorant you are, from:
https://en.wikipedia.org/wiki/Homopolar_motor
"B. G. Lamme described in 1912 a homopolar machine rated 2,000 kW, 260
V, 7,700 A and 1,200 rpm with 16 slip rings operating at a peripheral
velocity of 67 m/s. A unipolar generator rated 1,125 kW, 7.5 V 150,000
A, 514 rpm built in 1934 was installed in a U.S. steel mill for pipe
welding purposes."

If you think you can wriggle out of claiming a DC motor isn't a DC
motor, and then claim a unipolar device has no practical use you should
consider seeing your doctor or simply stop spouting your ignorance on
subjects you know nothing about.

1912 Riiiight.
So where are they nowadays?
A dead end invention.

On Saturday, 13 August 2016 20:22:17 UTC+1, Tim Lamb wrote:
In message ,
harry writes
On Saturday, 13 August 2016 08:18:46 UTC+1, charles wrote:
In article ,
harry wrote:
On Friday, 12 August 2016 10:24:48 UTC+1, Dave Plowman (News) wrote:
In article ,
Clive George wrote:
Yup. Although the bottle type tended to give a brighter light in the
days when I cycled. But a friction drive is horribly inefficient.

Sturmey hub vs other bottle? Yes, the sturmey hub wasn't very
powerful - the wheel turns quite slowly, so the magnets required
weren't available (or at least not at a sane price) back then. The
modern hub dynamos give rather more.

That certainly makes sense. Modern low voltage DC motors have also been
improved out of all recognition by better magnets.

There is no such thing as a DC motor.
I've told you before.

does that mean that those hand held fans run from a battery need an
inverter to work? I think not. And I'm sure the starter motot in my car
runs on DC.


No it runs on AC.
The "commutator and brushes" are a mechanical inverter.

These are expensive and wear out so these days it's replaced with
electronics to turn DC to AC where ever possible.

Hmm.. suppose the commutator is simply switching the current to a
different winding on the armature? Direction of flow may not change
which appears to me to be DC.

The current direction reverses as the commutator segnebt passes under the brush.

On Sunday, 14 August 2016 01:42:30 UTC+1, Fredxxx wrote:
On 13/08/2016 17:56, harry wrote:
On Saturday, 13 August 2016 08:18:46 UTC+1, charles wrote:
In article ,
harry wrote:
On Friday, 12 August 2016 10:24:48 UTC+1, Dave Plowman (News) wrote:
In article ,
Clive George wrote:
Yup. Although the bottle type tended to give a brighter light in the
days when I cycled. But a friction drive is horribly inefficient.

Sturmey hub vs other bottle? Yes, the sturmey hub wasn't very
powerful - the wheel turns quite slowly, so the magnets required
weren't available (or at least not at a sane price) back then. The
modern hub dynamos give rather more.

That certainly makes sense. Modern low voltage DC motors have also been
improved out of all recognition by better magnets.

There is no such thing as a DC motor.
I've told you before.

does that mean that those hand held fans run from a battery need an
inverter to work? I think not. And I'm sure the starter motot in my car
runs on DC.


No it runs on AC.
The "commutator and brushes" are a mechanical inverter.

driven by DC and hence called a DC motor.
https://en.wikipedia.org/wiki/DC_motor

You can deny "A DC motor is any of a class of electrical machines that
converts direct current electrical power into mechanical power" but to
do so only emphasises your ignorance.

These are expensive and wear out so these days it's replaced with electronics to turn DC to AC where ever possible.

Care to give examples of car starter motors that don't use brushes?

They need brushes and a commutator to convert the DC to AC.
Are you so thick you can't Google this?
https://en.wikipedia.org/wiki/Commutator_(electric)

On Saturday, 13 August 2016 10:25:36 UTC+1, Fredxxx wrote:
On 13/08/2016 06:55, harry wrote:
On Friday, 12 August 2016 10:24:48 UTC+1, Dave Plowman (News) wrote:
In article ,
Clive George wrote:
Yup. Although the bottle type tended to give a brighter light in the
days when I cycled. But a friction drive is horribly inefficient.

Sturmey hub vs other bottle? Yes, the sturmey hub wasn't very powerful -
the wheel turns quite slowly, so the magnets required weren't available
(or at least not at a sane price) back then. The modern hub dynamos give
rather more.

That certainly makes sense. Modern low voltage DC motors have also been
improved out of all recognition by better magnets.

There is no such thing as a DC motor.
I've told you before.

So what type of voltage do you apply to a "low voltage DC motor"?

It runs on AC. It needs a mechanical inverter to make it run.
https://en.wikipedia.org/wiki/Commutator_(electric)

On Saturday, 13 August 2016 08:18:46 UTC+1, charles wrote:
In article ,
harry wrote:
On Friday, 12 August 2016 10:24:48 UTC+1, Dave Plowman (News) wrote:
In article ,
Clive George wrote:
Yup. Although the bottle type tended to give a brighter light in the
days when I cycled. But a friction drive is horribly inefficient.

Sturmey hub vs other bottle? Yes, the sturmey hub wasn't very
powerful - the wheel turns quite slowly, so the magnets required
weren't available (or at least not at a sane price) back then. The
modern hub dynamos give rather more.

That certainly makes sense. Modern low voltage DC motors have also been
improved out of all recognition by better magnets.

There is no such thing as a DC motor.
I've told you before.

does that mean that those hand held fans run from a battery need an
inverter to work? I think not. And I'm sure the starter motot in my car
runs on DC.

Yes they have one built in.
https://en.wikipedia.org/wiki/Commutator_(electric)

On Sunday, 14 August 2016 06:16:30 UTC+1, harry wrote:
On Sunday, 14 August 2016 01:42:30 UTC+1, Fredxxx wrote:
On 13/08/2016 17:56, harry wrote:
On Saturday, 13 August 2016 08:18:46 UTC+1, charles wrote:
In article ,
harry wrote:

There is no such thing as a DC motor.
I've told you before.

does that mean that those hand held fans run from a battery need an
inverter to work? I think not. And I'm sure the starter motot in my car
runs on DC.


No it runs on AC.
The "commutator and brushes" are a mechanical inverter.

driven by DC and hence called a DC motor.
https://en.wikipedia.org/wiki/DC_motor

You can deny "A DC motor is any of a class of electrical machines that
converts direct current electrical power into mechanical power" but to
do so only emphasises your ignorance.

These are expensive and wear out so these days it's replaced with electronics to turn DC to AC where ever possible.

Care to give examples of car starter motors that don't use brushes?

They need brushes and a commutator to convert the DC to AC.
Are you so thick you can't Google this?
https://en.wikipedia.org/wiki/Commutator_(electric)

This argument crops up every now & then. It's fatuous.


NT

In article , harry
wrote:
On Saturday, 13 August 2016 10:25:36 UTC+1, Fredxxx wrote:
On 13/08/2016 06:55, harry wrote:
On Friday, 12 August 2016 10:24:48 UTC+1, Dave Plowman (News) wrote:
In article ,
Clive George wrote:
Yup. Although the bottle type tended to give a brighter light in
the days when I cycled. But a friction drive is horribly
inefficient.

Sturmey hub vs other bottle? Yes, the sturmey hub wasn't very
powerful - the wheel turns quite slowly, so the magnets required
weren't available (or at least not at a sane price) back then. The
modern hub dynamos give rather more.

That certainly makes sense. Modern low voltage DC motors have also
been improved out of all recognition by better magnets.

There is no such thing as a DC motor. I've told you before.

So what type of voltage do you apply to a "low voltage DC motor"?

It runs on AC. It needs a mechanical inverter to make it run.
https://en.wikipedia.org/wiki/Commutator_(electric)

sitting in front of me on my desk is a small fan which runs directly form
the 5v DC USB supply. There is no mechanical inverter.

--
from KT24 in Surrey, England

On Sun, 14 Aug 2016 09:15:36 +0100, charles
wrote:

In article , harry
wrote:
On Saturday, 13 August 2016 10:25:36 UTC+1, Fredxxx wrote:
On 13/08/2016 06:55, harry wrote:
On Friday, 12 August 2016 10:24:48 UTC+1, Dave Plowman (News) wrote:
In article ,
Clive George wrote:
Yup. Although the bottle type tended to give a brighter light in
the days when I cycled. But a friction drive is horribly
inefficient.

Sturmey hub vs other bottle? Yes, the sturmey hub wasn't very
powerful - the wheel turns quite slowly, so the magnets required
weren't available (or at least not at a sane price) back then. The
modern hub dynamos give rather more.

That certainly makes sense. Modern low voltage DC motors have also
been improved out of all recognition by better magnets.

There is no such thing as a DC motor. I've told you before.

So what type of voltage do you apply to a "low voltage DC motor"?

It runs on AC. It needs a mechanical inverter to make it run.
https://en.wikipedia.org/wiki/Commutator_(electric)

sitting in front of me on my desk is a small fan which runs directly form
the 5v DC USB supply. There is no mechanical inverter.


Of course, it's just harry desperately trying to justify the
unjustifiable to fit his warped ideas. Talking of FIT, I fitted a
small solar powered light on the shed yesterday and will be sending
harry the bill. Only seems fair as I'm am (well, 'we' are) subsidising
him and weren't asked if that would be ok.

For some reason though I bet he'll try to wriggle his way out of it.

I wonder if my panel picked up light from a light version of a pulsar
harry would say it was producing AC (as opposed to PWM DC with some
value of duty cycle)?

Cheers, T i m

In message ,
harry writes
On Saturday, 13 August 2016 20:22:17 UTC+1, Tim Lamb wrote:
These are expensive and wear out so these days it's replaced with
electronics to turn DC to AC where ever possible.

Hmm.. suppose the commutator is simply switching the current to a
different winding on the armature? Direction of flow may not change
which appears to me to be DC.

The current direction reverses as the commutator segnebt passes under
the brush.

You mean the armature is wound such that the magnetic flux generated by
the winding is reversed?

--
Tim Lamb