Re: Air cored Tesla coils for high voltage?

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi,

If you made it like a "continuous" DRSSTC driven by say a small motor 
H-bridge IC.  There is a "chance" you could make it "lighter"...  The 
coupling would probably have to be more optimal (0.6) which could be a 
problem...  An epoxy impregnated air core like the GMHEICSLR would be nice 
since the epoxy solves a lot of HV clearance issues.

I have a design for a few amp little charged pumped H-Bridge that is very 
small and light.  About the size of a quarter using surface mount ICs and 
such.  I could dig it up...  I think it could run at 100kHz++  It would 
need primary current feedback added and brought to the input...  The rail 
voltage would be pretty low which might be a problem...  Best to go for 
high battery voltage at lower current in that case.

Nice to know this thread is about Tesla coils ;-))

Cheers,

        Terry


At 06:00 AM 7/2/2005, you wrote:


> >  So my question could you make the transformers to
> > power a tesla coil be air cored?
>
> Yes. It's possible to make completely air-cored solid state Tesla coils. 
> There is no HV transformer needed- the coil itself is the step-up 
> transformer and it could run directly off 30V DC. The high frequency 
> inverter that drives it can be very small and light too.
>
> However, they may not be the best solution. An air cored transformer needs 
> to be resonant, and that implies higher current flow for the same output. 
> A Q of 6 is usual, and that means the wire is carrying 6 times more 
> current than a non-resonant transformer or C-W multiplier would. So it 
> needs to be thicker, hence heavier, if it's not to burn out.
>
> Ferrite transformers will work well even if non-resonant. So, while 
> ferrites are heavy, I would bet they would save more than their own weight 
> in copper. These are calculations _you_ will have to do if you're 
> interested in getting an autonomous lifter off the ground ;)
>
> But I notice that military and space HV supplies- where weight really 
> counts- are all made with a HF inverter driving a ferrite transformer that 
> drives a C-W multiplier stack.
>
>
> >  Then another question is could you make the toroid on
> > the tesla coil be lightweight?
>
> You don't always need one. Sometimes the self capacitance of the coil is 
> enough, if not you can add a series string of small ceramic disc caps. If 
> you use a ferrite transformer then you definitely don't need one ;)
>
> Steve Conner