Are Tesla Coils really special?

[fog37]

Hello,

I have heard so much about Tesla coils in the context of wireless electricity.

I think I understand how a transformer works: there are two metal coils, near each other. A time-changing current in the primary coil generate a time changing electromagnetic field that is captured by the secondary coil (electromagnetic induction). The secondary coil now has an induced current.

What is special about a Tesla coil? Is it just a transformer that works at a higher frequency? I believe the two coils still need to be relatively close to each other...

Thanks,
fog37

 

[Jeff Rosenbury]

There's a little more to a Tesla coil.

A standard transformer works by concentrating the power with an iron core. The iron core keeps the energy from wandering out into space.

A Tesla coil encourages the energy to wander. The second coil is set up to resonate with the first coil. Thus the wandering electric field (the near field) is picked up by the second coil. The low Q of the first coil keeps losses low until the second coil can pick up the energy.

So in a standard power transformer, the quality of the iron is critical. In a Tesla coil, the quality of the resonance is critical.

 

[fog37]

Thanks Jeff.

I understand the role of the iron core in a regular transformer but I am not clear on the resonance aspect for the Tesla coil.

How is the resonance controlled? By the size and number of turn in each coil and the frequency used in the first coil?

How far can the two Tesla coils be?

Thanks.

 

[anorlunda]

There is a lot of information here

https://en.wikipedia.org/wiki/Tesla_coil

Please read that first, then if you still have questions, come back to PF.