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Back again, Was "Generate -100V"

Discussion in 'General Electronics' started by Denis Gleeson, Jun 4, 2004.

  1. Dear all

    Many thanks to all who contributed to my question about generating
    -100V. Given
    below for the readers information.

    To test the possibilities with the LM3578 I was using a TIP30A as the
    pass transistor.
    I followed Figure 21 in the data sheet. (some one said its at
    http://cache.national.com/ds/lm/lm1578A.pdf)
    I used a 22uH 0.7A inductor because it was handy. I was also building
    the thing on a plug in test board.

    To follow up on some of the replies:

    I said I didnt want to use a transformer and this is for a couple of
    reasons that may not actually be valid. Im un-familiar with their
    use(this is valid). I perceive them as being bulky and I need to make
    a small PCB size for the product. I think they are expensive and if I
    can get away without one Ill save money.

    So if anyone can enlighten me and tell me where Ill get a suitable,
    small and inexpensive transformer then Im interested.

    Winfield Hill had some interesting things to say:
    I wonder if you would explain these figures further Winfield.
    I cant see where the 833mA or 1.89A peak come from. Im not questioning
    them I
    just need to understand how they are derived.

    I think the transistor I chose was ok but the inductor selection seems
    to be a big issue for me. Anybody got any pointers on what size and
    rating inductor I need.

    Many thanks to all again.

    Denis
     
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