OT - generating electricity on a bicycle

[harry]

Toys are all they are these days. A dead end technology.

[Fredxxx]

Do you still apply AC to a DC motor?

And I'm not talking about AC motors or universal motors.

[Fredxxx]

Are you now saying that you do apply DC to a DC motor?

[Fredxxx]

Do you still deny you apply DC to a DC motor?

[tabbypurr]

Ignore him, he's on his trolly trip.

NT

[The Natural Philosopher]

If its a brushless, yes.

And *if* you consider the motor is the far side of the commutator, yes.

The problem lies in the definition of 'motor' and 'DC motor'.

Is a motor designed ultimately to work on DC, a DC motor, when its terminals are clearly fed with AC?

[tony sayer]

No Harry .. thats switched reversed polarity DC;)...

[Fredxxx]

So you and harry would apply AC to a DC motor. Sheeez.

I thought you knew better. Yes I know all about commutation, brushed and brushless, but the significant thing about a DC motor is you apply DC to it. What happens inside the box isn't helpful.

Next you and harry will be saying that there is no such thing as an electrically powered motor, they're all magnetic.

[Dave Plowman (News)]

Well, yes. AC is generally a sine wave. Be good to see how you achieve that with a switch. Many inverters make a pretty poor job of producing a sine wave. ;-)

[The Natural Philosopher]

...otherwise known as 'AC'...

[harry]

AC can be any wave form. Sine/cosine wave forma re associated with rotating electrical machines. Simple switching gives a square wave. In a commutator, the point where the sine wave crosses the base line is where the brushes are ituated. Theoretically.

Changing the load/reversing needs the brushes to be moved ideally. If they aren't moved excessive arcing occurs which damages the commutator.

[harry]

Quite true. Electricity is convenient way of producing the two magnetic fields neccesary. Neodymium magnets have replaced electricity for one of the magnetic field in some cases.

[harry]

There ARE such things. Allegedly.

[The Natural Philosopher]

Well obviously from the comment above you DO NOT know what a brushless motor is, because if you apply DC to it, it melts.

It needs a controller which is usually externnal to the motor.

AS I keep saying, its a matter of what you call a motor.

Is this, for example, a DC or an AC motor?

Or only 'part of' a motor?

[Fredxxx]

The last 12V fan was brushless and was designed for 12V DC. There was no external controller and when I applied 12V DC to it it didn't melt.

Perhaps you should get your brushless DC motors from more reputable sources that include their own commutation, electronic or otherwise.

You are harry's sock puppet who believes that you should not apply DC to a DC motor.

[Fredxxx]

Ah, so we are now saying DC is a special case of AC.

[Tim+]

Where does this fit in the scheme of things?

Tim

[The Natural Philosopher]

No. the current and voltage have to reverse to be alternating.

I see your command of English is as poor as your understanding of motor theory.

[The Natural Philosopher]

Think that's another unipolar

[Fredxxx]

Its not a unipolar motor. It's commonly called a ball bearing motor attributed to Stefan Marinov.

It relies on the thermal expansion of the balls in a ball bearing.