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Re: [TCML] Permanent Magnet GDT(?)
Correct me if I am wrong, but won't running a current of any type
through windings on a magnet render it non magnetic in short order?
Scott Bogard.
On 5/31/11, Christopher Karr <chriskarr4@xxxxxxxxxxx> wrote:
>
> Mike, all,
>
>
> I understand that the magnetic material is already close to saturation
> when fully magnetized, as in a permanent magnet, but can that nearness
> to saturation not be reversed by applying an opposition to the current
> magnetic field?
>
> Here's a small example to illustrate what's in my mind:
>
> If you bias a core in one direction with a constant DC voltage of 9V (let's
> neglect current, for our purposes), you get what is akin to a permanent
> magnet. If you add two windings, one a primary and one a secondary, you will
> have a total of three windings - 1 = Bias; 2 = Primary; 3 = Secondary
>
> These are the theoretical voltages on each winding, with (2) as the
> independent variable:
>
> Zero degrees:
> 1 = 9V+ 2 = 0V 3 = 9V+
>
> Ninety degrees:
> 1 = 9V+ 2 = 0V- 3 = V0
>
> One-hundred-eighty degrees:
>
> 1 = 9V+ 2 = 18V- 3 = 9V-
>
> Two-hundred-seventy degrees:
>
> 1 = 9V+ 2 = 18V- 3 = 9V-
>
> (This is assuming a perfect square-wave on winding 2, no losses and no noise
> created)
>
>
> I understand that I'm overlooking the fact that current is induced by change
> in flux and at 270 degrees there hasn't been a change in flux for an entire
> quarter-cycle, but my thought is that, given sufficient protection to
> reversals on winding 2, winding 3 would effectively average out the
> difference.
>
> Thank you, again, for your time,
>
> - Christopher
>
>
>> Date: Mon, 30 May 2011 22:58:31 -0400
>> Subject: Re: [TCML] Permanent Magnet GDT(?)
>> From: mdt24@xxxxxxxx
>> To: tesla@xxxxxxxxxx
>>
>> Having a permanent magnet core wouldn't cause any difference on the output
>> of the transformer. It simply biases the core material with a large
>> initial
>> flux. The AC component of the flux swing would not change, and that
>> determines the output. Using a magnetic core would just be likely to
>> saturate the core sooner. Also it would probably buzz quite a bit.
>>
>> -Mike
>>
>> On Mon, May 30, 2011 at 3:48 PM, Christopher Karr
>> <chriskarr4@xxxxxxxxxxx>wrote:
>>
>> >
>> > Good day, Everyone,
>> >
>> > 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. This
>> > would
>> > - in my mind - give rise to an extremely simple push-pull gate signal.
>> >
>> > 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.
>> >
>> > Feel free to make corrections, or even tell me I'm *way* off-base. If I
>> > knew for sure, I wouldn't be asking. *wink*
>> >
>> > Thank you for your time,
>> >
>> > Best wishes,
>> >
>> > - Christopher
>> >
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