Re: [TCML] Permanent Magnet GDT(?)

[dave pierson <dave_p@xxxxxxxxxxx>]

 There are subtleties here.

> Having a permanent magnet core wouldn't cause any difference on the
> output of the transformer.
     I'd expect the output would change.
     If the 'permananet' field has 'used up' some of the
     available 'flux capacity', then the output can't track
     the input..  One would expect not partiularly efficient
     quasi rectifier effect.

>  It simply biases the core material with a large initial
> flux.
    Agreed.

> The AC component of the flux swing would not change,
    I believe it would.  The direction of swing where 'some/all'
    of the 'flux capacity' (ability of the core to handle
    flux lines.) is used up means the putput would not see
    the 'swing'

> and that determines the output.  Using a magnetic core
     Permananent megnetic core?
     (Most cores are magnetic, until rf....)

> would just be likely to saturate the core sooner.
     Agreed.

  Also it would probably buzz quite a bit.

>> I've been pondering this topic for some time, now, and I've been
>> wondering if it were reasonable to use a ferrite permanent magnet
>> (in toroidal shape) as a core for a GDT.

> > My thinking is based on the fact that transformer action is based
>> on changing magnetic flux, so if the primary of such a GDT
>> were driven in a single-ended configuration with the magnetizing
>> current opposing the natural flux of the magnet, during the
>> 'dead time' of the signal, a full flux-reversal would be made,
>> naturally, by the magnetic material.
    [My comments above Assume common sinewavish bipolar drive:
     the unipolar case will differ...]

>> This would - in my mind - give rise to an extremely simple push-pull
>> gatesignal.

> > The only problem I see, prior to receiving your answers, is the
>> complete lack of control over one half of the waveform, since it
>> would be determined solely by the properties of the magnetic
>> material.

   best
    dwp
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