Re: Online source for high power MOSFETs and FETs?

From: Walter Harley (walterh_at_cafewalterNOSPAM.com)
Date: 09/17/04

  • Next message: Robert Wolcott: "Re: Online source for high power MOSFETs and FETs?" 
    Date: Thu, 16 Sep 2004 18:41:05 -0700

    "Robert Wolcott" <rwolcott23@yahoo.com> wrote in message
    news:9f2dnezQ0rzqsdfcRVn-qA@comcast.com...
    > Walter,
    > Thanks for the reply. This is what I really need to accomplish:
    >
    > http://oregonstate.edu/~wolcottr/Switching%20supply%20outline.jpg
    >
    > Do you have an idea what the components for this would cost? I am
    > designing a 20 watt copper halide laser as a senior project. I could
    > probably get some help from the EE department with design but cost is a
    > concern. Do you have experience with this sort of thing? I would be able
    > to build the transformer as well, I think.
    >
    > Thanks,
    > Bob

    I don't have much experience with switch-mode supplies, especially not ones
    intended to generate 11kV at 1.5kW. But I have enough experience to say
    this: that's a hell of a lot of energy to be mucking around with.

    Even small switch-mode supplies sometimes go "bang" during development; but
    when a 1.5kW supply goes "bang" it takes other things with it. And voltages
    in the tens of kV encourage things to go "bang".

    If I were you, I would do two things:

    1. Get help from someone who really knows what they're doing (meaning at the
    very *least* that they have successfully designed and built a high-power
    high-voltage supply in the past), or purchase a commercially available
    supply (yes, expensive).

    2. Thoroughly ignore the advice of anyone (such as me) who doesn't have
    credentials in this area. There are some good switch-mode supply designers
    on sci.electronics.design, but I am not one of them; and in general the
    Internet contains a lot more people who think they know what they're talking
    about than who actually do.

    Or, you could just string together a bunch of neon sign transformers, and
    pray. After all, there's no reason you need a switch-mode supply; you're
    just trying to generate some high voltage, right? The primary advantages of
    a switching supply are that it can efficiently regulate voltage over a range
    of input voltages and output loads, and that because of the high
    frequencies, the transformer can be smaller and lighter. But neither of
    those matter to you, as I see it. Why not just use good old 60Hz AC?
    There's a bit of insight on that approach at
    http://home.earthlink.net/~jimlux/hv/xfrmr1.htm.

  • Next message: Robert Wolcott: "Re: Online source for high power MOSFETs and FETs?"

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