On 14/08/16 16:28, Fredxxx wrote:
On 14/08/2016 06:18, 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.

I don't see any transformation of DC to AC I apply to my car starter
motor? In fact all I have is a 12V battery and a switch.


Well no you wouldn't. That's what the commutator is - a mechanical inverter.


Perhaps you live a sheltered life?

Perhaps you are ignorant of how an electric motor works....?

--
"The great thing about Glasgow is that if there's a nuclear attack it'll
look exactly the same afterwards."

Billy Connolly