OT - generating electricity on a bicycle

[Tim Streater]

Does that run on magnetic monopoles?

[Fredxxx]

No, homopoles!

[Johnny B Good]

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

[harry]

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.

[harry]

A laboratory device of little/no practical use. There's one here:-

Doesn't it look useful?

[Tim Lamb]

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.

[Fredxxx]

I can't believe how ignorant you are, from:

"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.

[Fredxxx]

driven by DC and hence called a 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.

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

[harry]

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

[harry]

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

[harry]

They need brushes and a commutator to convert the DC to AC. Are you so thick you can't Google this?

[harry]

It runs on AC. It needs a mechanical inverter to make it run.

[harry]

Yes they have one built in.

[tabbypurr]

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

NT

[charles]

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.

[T i m]

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

[Tim Lamb]

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

[Tim Streater]

What's all this about brushes that harry is rabbitting on about. Didn't think motors had those these days (unlike the cheapies that ran toy electric trains when I was a nipper).

[The Natural Philosopher]

Then there is an electronic one

[The Natural Philosopher]

Some do, some don't.

If they are DC motors and they dont have brushes, they have electronics doing the same job.