OT - generating electricity on a bicycle

[Fredxxx]

So you are starting to admit that you supply DC to a DC motor.

Or are you the sort to suggest you should supply a DC motor with AC?

[Fredxxx]

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.

Perhaps you live a sheltered life?

[Fredxxx]

The synchronous application of voltage to a motor winding is normally called commutation, and the definition of "inverter" it is the means of converting DC to AC.

If I should apply an AC current from Harry's inverter to a DC motor, with a permanent magnet providing the field, I'm sure all you would hear is a hum.

Nevertheless, I would still apply DC to a DC motor.

[Fredxxx]

Clearly you are innumerate as well.

Try 1934, and you can find out for yourself how long this generator was used for.

[NY]

Will a motor that is designed to run on DC turn if you connect it to AC? No. It will buzz and vibrate. Will a motor that is designed to run on AC work if you feed it DC? No. The rotor will probably give a convulsive jerk and then stop.

A "DC motor" (one that is designed to run from a DC supply) has a commutator to energise the various coils in the rotor, in sequence, as the rotor turns through a stationary magnetic field from a permanent or electro magnet in the motor casing.

[Fredxxx]

I agree with you, and there is a consensus here that they are still called DC motors.

[harry]

Then it has an electronic one. Which takes us right back to the start of the post. There is an inverter. mechanical or electronic.

[harry]

Most "DC motors" will run on AC. Provided the the field magnet is NOT a permanent magnet. Their other name is a "universal motor" As found in traditional vacuum cleaners. (Not modern digital ones which have electronic rectification/invertion.)

[Fredxxx]

The only person here who doesn't agree with that statement is Harry.

[harry]

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.

You might also look at this.

[The Natural Philosopher]

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

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

[The Natural Philosopher]

Some will, yes.

Depnds.

No. The rotor will probably give a convulsive

I.e to turn the DC into AC synchronised with the shaft speed.

[The Natural Philosopher]

What something is called and what it is, are often wildly different.

I've heard comrade Corbyn referred to as intelligent and compassionate.

[Fredxxx]

Is it so hard to say "DC"?

[Dave Plowman (News)]

Common to refer to motors as AC, DC, or universal. Except in the likes of harry's fantasy world.

And just what makes harry think I was referring to model aircraft motors?

[Johnny B Good]

My apologies for not directly responding to Harry's attempt to respond to my follow up to your post but I have him killfiled so only see his activity via quotage.

Quite frankly, he didn't deserve responding to since he neglected to follow that wiki link, preferring to find something else off youtube as an example to back up his unsubstantiated claim that homopolar motors are

*only* toys with no real world applications.

Quite clearly, you're only wasting your own time by "Confusing him with Facts" that conflict with his own preconceived ideas. :-)

The only reason why I bothered to 'jump in' was simply to post that wikipedia link so that anyone in doubt and in danger of accepting Harry's false assertions as even remotely plausibly true would see these assertions for what they are, a load of bollix!

[Johnny B Good]

Actually, the phrase used is "DC Brushless Motor". In this case, the motor itself is actually an AC motor but the incorporation of a DC to AC converter which allows them to be powered from (and *only* from) a DC voltage supply allows them to be used in place of the classic mechanically synchronized commutated motor using brush gear (but without the problems of commutator and brush wear and friction) hence their name, "Brushless DC Motor".

The homopolar motor is a unique form of true DC motor where only slip rings are required to energise the rotor without any form of commutation being required. The major problem is their limitation to very low voltage high current applications unless you're prepared to design them for extremely high speeds of rotation on even very low voltage high current supplies (say a large 2v lead acid accumulator cell or a very large NiCd or KniFe cell).

[harry]

No they are AC motors with an electronic inverter. There is no commutator these days.

[harry]

The current is reversed as it passes under a brush turning it into AC.

[harry]

It was TNP. He is into model aircraft. As I once was.