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frequency change


----------
From:  Andrew Chin [SMTP:chinny-at-ozemail-dot-com.au]
Sent:  Wednesday, March 11, 1998 6:11 AM
To:  Tesla List
Subject:  Re: frequency change

    I actually thought of doing this at one stage.  Running a high voltage
transformer at the resonant frequency on the mains side, such that it will
ring the primary at the same frequency.  The problem is that getting a high
voltage transformer to run at the frequencies of a Tesla coil (about 200kHz
for mine), is a feat to be seen.  Sure you can try and build your own
transformer, and this would take remarkable engineering skills.

    If you're thinking of maybe running a NST at that frequency, you can
forget it.  You'll most likely saturate the transformer and it will start
getting hot.  I tried this method and could only get the NST to 450Hz!!

    There is an alternative scheme that I devised, which involves using
several transformers, and pulse them each in turn.  The following diagram
will hopefully explain:

Transformer 1:    __                  __                 __
__
                         |  |                  |  |                 |  |
|  |
                    ___|  |__________|  |__________|  |__________|
|_____________

Transformer 2:         __                  __                 __
__
                              |  |                  |  |                 |
|                  |  |
                    ______|  |__________|  |__________|  |__________|
|__________

Transformer 3::              __                  __                 __
__
                                    |  |                 |  |
|  |                 |  |
                    _________|  |__________|  |__________|  |__________|
|_______

Transformer 4::                   __                  __                 __
__
                                         |  |                  |  |
|  |                 |  |
                    ____________|  |__________|  |__________|  |__________|
|_____

(excuse the ASCII art)

By doing this, you can keep the frequency to the indvidual transformers
within the tranformers capabilities.  You can then combine the outputs
together to get a frequency, in this case, 4 times the frequency of the
transformer.  i.e.  if you wanted to operate a 200kHz coil, you could get 4
transformers and run each at 50kHz.  You can see that this scheme can be
easily expanded to incorporate more transformers.

The critical thing with this method is getting the timing right, and this
usually means a single oscillator running some logic which does the wave
shaping.  In the example above I showed pulses for clarity.  In practice,
you could do it with a sinewave, and even a squarewave, swinging from
positive to negative. (using H-drive)

I never got around to testing this scheme due to the lack of transformers,
but I have simulated and built the logic circuits to it, and it is flawless.

To get to the point, you really need to get hold of some high frequency,
high voltage transformers, for this method of ringing the primary to work.

I'd also like to hear from anyone else who tried to alter the frequency on
the mains side of the transformer.

Andrew Chin    chinny-at-ozemail-dot-com.au

-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: 'Tesla List' <tesla-at-pupman-dot-com>
Date: Tuesday, 10 March 1998 10:27 AM
Subject: frequency change


>
>----------
>From:  Fox [SMTP:fox-at-netunlimited-dot-net]
>Sent:  Sunday, March 08, 1998 4:56 PM
>To:  tesla-at-pupman-dot-com
>Subject:  frequency change
>
>would it be possible (if the transformaer could handle it) to up the
>frequency with a solid state device on the mains side therby eliminating
>a hot noisy gap and expensive cap
>i think itd look like this
>
>________   _____  E
>mains  |  |   3E         3E
>_____|_|__3E____3E
> frequency    |
>changed       |
>here           hi volt tranny
>
>
>