Electromagnet polarity switching....

[NTL2009]

Thank you to all who contributed. Sorry if you feel I have not supplied sufficient information. I can only say I cannot think of a way to make, "I just want to be able to rapidly change the polarity of ANY two electro magnets simultaneously. (Interaction with permanent magnets experiment.)" any clearer. ...

No, it is not clear, and part of the reason is there is no context.

Provide some context, what exactly are you trying to show your grandchildren? It is not clear what you are trying to accomplish by 'rapidly' changing polarity "once per second to hundreds of times per second". Why those numbers? What are you trying to show?

At one point you said "If outcome is as I anticipate," - OK, what do you anticipate? If you communicated this, people could likely tell you how to accomplish this, or maybe something better/easier to educate/entertain your grandchildren.

You may not need much in the way of equipment - there are online tone generators on the web, here's one, search turns up many more:

http://onlinetonegenerator.com/

Some electromagnets (or loudspeakers, as has been mentioned several times), connected to an audio amplifier might be all you need to demonstrate something, but we don't know what that "something" is.

Despite your feeling that you are being clear, it should be clear from all the questions that you are not.

 

[sophiecentaur]

Thanks. I will outcome post if and when I am fit enough and get the necessary equipment.

What necessary equipment?
I think you do not realize that a random set of scientific equipment, used in a random way will produce very little and probably nothing. It's monkeys and typewriters.

If you are trying to entertain and inform your grandchildren then you owe it to them to do it right and plan a proper demonstration. You really don't want to teach them that Science Never Works, do you?

 

[Tom.G]

At the risk of being ostracised, here goes.

if anyone could advise where I could obtain a device (including magnets) which will change the polarity of two electro magnets from once per second to hundreds of times per second?

Come On Guys! There was a straight forward request for information from the start, and I think we let him down. He admitted to no knowledge in electronics or magnetics and with a ballpark size estimate added later. However some responders wanted to answer a different question, some wanted to use a computer and some didn't, some wanted more context, some asked how the results were going to be measured, some suggested a 'free energy' connection, some wanted to know the anticipated results, some accused the OP of being unclear in the requirements; and I'm tired of typing.

The OP is obviously trying to learn by doing an experiment. Good for him! That's the Scientific Method.

I would say the electro magnets would be rectangular and about two inches long.
Ideally, I see the device to have a dial which could be rotated to increase the number of times the polarity would be switched.

I just need to get ANY two electromagnets polarity simultaneously, rapidly controlled.

basically I just need to be able to control rapid switching of polarity of two electro magnets.

virtually ANY size and power will be sufficient

I don't have problem with electro magnets per se. Just how to rapidly change polarity.

Tom

 

[sophiecentaur]

The OP is obviously trying to learn by doing an experiment. Good for him! That's the Scientific Method.

That may be a way of teaching when the "doing" is well directed by a teacher. It is not 'scientific' to blunder about randomly because, as I have already said, the results are nearly always zero. The scientific method is to build up on an established body of knowledge. The Brownian approach to a journey is not the best.
The advice in this thread has been (typically for PF) a bit confusing for a beginner and that's because the OP asks about a very vague 'effect' of an alternating field from two electromagnets.
10/10 for wanting to give the grandchildren an interesting time but a good lesson depends entirely on good lesson preparation.

 

[Bo Cash]

It is not my intention to upset people or mislead them. This was never my intention. If people are frustrated by the lack of information I can supply, I can only apologise.
As Tom.G says, as far as I believed, it was a straightforward request. Nothing more.
If, I repeat, IF someone knows how I may set up ANY two magnets (I do know how to make or purchase such) and rapidly, simultaneously change their polarity, that is all I require. I don't understand the need to be supply size, current or even which colour might be best. I just require a system which will work for ANY two electro magnets. I reckon I would start with magnets around two inches long. That is the only information I can think of to offer.
My stage of comprehension at this stage is that I need to have a signal generator connected to an audio amp connected to the magnets. I am exploring this.
With signal generators on eBay at $3 and others at £3,000, I am trying to discover what I need. With no knowledge of how to check compatibility or actual connections, I trust the experts understand my dilemmas.
I would like to make it clear I appreciate the time and effort from all contributors.

 

[NTL2009]

It is not my intention to upset people or mislead them. This was never my intention. If people are frustrated by the lack of information I can supply, I can only apologise. ...

No need to apologize, I don't think people are upset, only frustrated, because we are trying to help you and your grandchildren. But you admit you have little knowledge in this area, yet, you question why we ask for the info we ask for. There is a reason - we want to help you and we need more info to do that. We know enough to know that and you (respectfully) do not.

So help us help you.

As Tom.G says, as far as I believed, it was a straightforward request. Nothing more.
If, I repeat, IF someone knows how I may set up ANY two magnets (I do know how to make or purchase such) and rapidly, simultaneously change their polarity, that is all I require. I don't understand the need to be supply size, current or even which colour might be best. I just require a system which will work for ANY two electro magnets. I reckon I would start with magnets around two inches long. That is the only information I can think of to offer.
My stage of comprehension at this stage is that I need to have a signal generator connected to an audio amp connected to the magnets. I am exploring this.
With signal generators on eBay at $3 and others at £3,000, I am trying to discover what I need. With no knowledge of how to check compatibility or actual connections, I trust the experts understand my dilemmas.
I would like to make it clear I appreciate the time and effort from all contributors.

No one system will work for ANY two magnets. Saying "two inches long" tells us very little, because you have not really told us why you want to switch polarity, what effect you hope to demonstrate, or why the several to hundreds of cycles per second is relevant to anything.

Why so secretive - just spit it out! What is it you are actually trying to demonstrate. Details, please! If you can't do that, I'm out.

To many of us, your question is a lot like "How long is a string?", and expecting a reasonable answer.

 

[sophiecentaur]

It is not my intention to upset people or mislead them.

I think most of us realize that but you need to help us by saying what you actually expect out of this. Would I be right in thinking that you want to hold the two magnets in your hand and feel the force between them?
Are you aware that, altering the polarity of each at the same time will not change the direction of the force between?
N-N poles, whilst S-S poles repel and N-S and S-N will attract so going from SS to NN will have the same effect.
One electromagnet only is needed if you want a force that changes direction.
As far as equipment is concerned, the sort of signal generator that would be idea for you would be a School Laboratory Oscillator, which will produce sine waves or square of very low frequency (Fractions of a Hz) up to several tens of kHz. You need a few Volts peak to peak output (say 5V) and the ability to feed a few Amps (more than that would make your coils too hot). Does that rough specification help you in selecting from eBay?
[Edit: I have seen transformer C Cores on google. These are marvellous for producing a horseshoe magnet (winding perhaps 50 turns on the centre of the C) . Two such magnets will stick together with just an amp or two through them and you cannot pull the apart. I wouldn't be surprised if you could lift a grandchild with the force.

 

[Windadct]

It seems a basic "elementary" curriculum in magnetism and motors - there are kits and pre-designed experiments available to cover this, and then there is a bit of guidance, vs miscellaneous playing around - which can still be done ( and needs to be) - but a foundation of specific learning steps is important.

Keep in mind a basic DC motor - has a polarity reversing electromagnet, that is how it works.

I think what threw a lot of people is the Frequency requirement - that seemed pretty specific, a loudspeaker does fit the bill.

 

[jim hardy]

The car alternator i suggested requires no electronics knowledge
and would let you excite the electromagnets simultaneously
or synchronously with 1/3 cycle of phase difference.
But it lacks the precision and easy adjustability of a function generator.

This outfit is in my hometown. They make permanent magnets. Do you need those too? What size?
https://azind.com/
Check their permanent magnet informational leaflets here. ...
https://3bjfj65j2skfse42ir91lknd-wp.../11/Permanent-Magnet-Guidlines-MMPAPMG-88.pdf
https://3bjfj65j2skfse42ir91lknd-wp...11/Permanent-Magnet-Materials-MMPA0100-00.pdf

That's a good site for speakerbuilding supplies surely there's somebody similar in UK.

This cheap little amplifier behind a function generator should drive a small electromagnet over the audio range.
https://www.parts-express.com/lepai...-stereo-amplifier-with-power-supply--310-3000
search on the brand - lots of places sell it and I'm not advertising for any of them.
I don't know how low it will go in frequency - its internal IC is capable of DC so probably changing an internal capacitor or two would get you down to subaudible frequencies. You'd want a stout power supply for that.
555 timer and function generator electronic hobbyist kits abound

Trying to be practical here and consider OP's probable experience level. - they'll learn as they go.

If the electromagnets don't work out grandkids can use that amp with their Iphones.
Teach them about Bass Reflex speakers and Thiele parameters - fine quality sound will bring them much joy in teenage years..
That's a good site for speakerbuilding supplies and surely there's somebody similar in UK.

old jim