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"?

He is talking about model aircraft motors which are much better than they once were.

If you want to understand modern high efficiency motors, here's where to start.
All made possible by rare earth magnets.
But these are synchronous motors.

https://en.wikipedia.org/wiki/Synchr..._magnet_motors

You might also look at this.
https://en.wikipedia.org/wiki/Brushl...electric_motor