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Stacking mosfets

Discussion in 'Hobby Electronics' started by Arpit, Sep 1, 2003.

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  1. Arpit

    Arpit Guest

    Hi, a design calls for some mosfets rated at about 20 amps and 500
    volts IRFP460 to be precice. But the mosfets I have access to only are
    rated at 200 volts, though have a substantial amperage rating. WOuld
    it be possible to stack them somehow in series or something to
    increase the effective voltage rating of the whole bunch?
  2. Mike Harding

    Mike Harding Guest

    In a word; No.

    500V is a serious voltage, unless you _really_ know
    what you are doing use the specified parts and don't
    mess with the design.

    What are you making?

    Mike Harding
  3. Arpit

    Arpit Guest

  4. Arpit

    Arpit Guest

    It'll probably only run off 315 volts or so, ie 240 volts rectified,
    and im used to that, thanks for the concern tho , makes me feel wanted
  5. Phil Allison

    Phil Allison Guest

    ** Arpit is a 16 year old.

    ............ Phil
  6. Victor Lamb

    Victor Lamb Guest

    So? What is your point? Many of us got into electronics when we were young.

    All the more reason to provide information and assistance to this person.
    It's better that they got the benefit of the experience of the people here,
    rather than put themselves at risk of injury, shock or causing damage to

    If I knew something about the use of MOSFET's in power applications, then I
    would tell Arpit something useful. Unfortunately I don't.

  7. Phil Allison

    Phil Allison Guest

    ** The danger to him.

    ** You must be a absolute idiot.

    ** Huh ?

    You are worse than I tought.

    ** Thank god for that.

    ............ Phil
  8. Mike Harding

    Mike Harding Guest

    To be fair to Phil I think that was exactly his reasoning.

    And he's right.

    That circuit is intended to run from 120V AC, if you
    connect it to 240V the voltage between "+350v"
    and "Power" will be closer to 700V! So you had
    better think carefully about the voltage ratings of
    BR2 and C15/C16. Not to mention all the other
    HV stuff on the secondary of T2 - and you'll need
    to upgrade (not downgrade) those MOSFETs.

    And keep in mind that with C15/C16 at 4700uF
    and 700V touching those is probably instant death.

    Arpit I fully understand the attraction of these sorts
    of circuits to you (we've all been there) but messing
    with that sort of stuff when you don't understand
    it may well kill you. Leave the high voltage stuff
    alone for now you need a lot more knowledge
    before you can work with it safely.

    Mike Harding
  9. Arpit

    Arpit Guest

    Yeah, I saw that, I'm just gonna run it off off my capacitor bank i
    made a couple of months ago- about 1500uf at 315 volts.
    What are some good books about the subject?
  10. Or do this (be careful), please exuse crude drawing and please heed all
    warning others have given, such as please do not attempt this at home - use
    it as a reference only.

    Live -----------/\ +----+------- 340Vdc
    / \ | |+
    +-<- +>------+ --- 4700uF
    | \ / --- 200V
    Neutral -----)---\/ |+
    | --- 4700uF
    | --- 200V
    | |
    +------------------+--------- 0V

    I also like to put bleeder resistors across each cap. Helps you not to get a
    belt after the unit has been sitting around.

    I was tought to always work with one hand behind my back!!
    Try getting hold of some Workplace Health and Saftey videos before you
    attempt anything. If they don't make you vomit, they will teach you to be
    extremely careful.
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