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One Power Supply to Rule them All

  1. Aug 4, 2015 #1
    I have a thing I want to build(scanning electron microscope) that requires like 5-10 different power supplies within the 1-20 kv range. Instead of building all of them, cant I build one 250kv power supply and split its power into all of these different high voltage components? How would you recommend this in the cheapest DIY, yet effective, orientation?
  2. jcsd
  3. Aug 4, 2015 #2


    Staff: Mentor

    Yikes! Those voltage levels can be lethal. We do not post advice on dangerous subjects on this public forum.

    You need the advice of a professional engineer.
  4. Aug 4, 2015 #3
    Everything on this forum can be considered dangerous. If it's a rule, you cant just be selective to what dangerous things can and cant be discussed. Im asking about electrical components and concepts that can be applied to minimizing the costs of a microscope. I am not in the possession of any electrical equipment at this time and would not commit actions based solely on smalltalk found here because I am, as far as I know, not retarded. Im here for information, not sensationalism. This is a question about a fully virtual design that does not exist in the real world and is therefore not dangerous.
  5. Aug 4, 2015 #4


    Staff: Mentor

    I have no knowledge of your qualifications. More important, I have no knowledge of who may read the archived thread in the future.
  6. Aug 4, 2015 #5

    jim hardy

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    why would you want 250k if your highest need is 20k?
    Build one 20.
    Every plasma globe and CRT TV set has one in it.
    Figure out how to add taps.
    Don't go over 25, that makes Xrays.
  7. Aug 4, 2015 #6
    So I can have a 20 kv power supply that supplies constant, regulated power to up to 10 different devices?
  8. Aug 4, 2015 #7

    jim hardy

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    You've put no numbers on anything - so nothing is yet impossible.
    Do you know your voltage and current needs ?
  9. Aug 4, 2015 #8
    It seems 10 killivolts is actually the top, not 20. I dont know those other values, they would be specific to what parts I could find after hunting for them on ebay and such. After looking at tap changers they seem to offer different voltages at different times, not simultaneously, but im assuming im wrong.
  10. Aug 4, 2015 #9


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    Understanding how a SEM works is one thing, building one from scratch is another. The design of the power supplies are the least of your worries. First design your electron optics, sample handling chambers and vacuum pumps. Then built it all and run it on voltages up to say 3kV. If you get that far, the EHT supply will be trivial.

    If you google and study the design of X-ray machine power supplies you will see how 1kV to 20kV variable voltage supplies are built. Insulation and corona prevention become critically important.

    For variable high voltages I use cheap and very dangerous oil filled power supplies from scrap or second hand X-ray machines. They are adjustable and current limited. The transformer insulation oil may contain PCB carcinogens. The machine may emit X-rays. Electrocution is not survivable because the burns are deep and the resulting fire will prevent rescue and make collection of evidence by the coroner difficult.
  11. Aug 4, 2015 #10


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    Staff: Mentor

    However, this is a public forum so everything posted goes not just to you but to thousands of other people. This thread is closed.

    No, because voltage isn't power and it doesn't divide that way. That's like asking if you can split the air flow coming out of a 400 psi compressor to simultaneously fill 40 tyres each with a safe pressure limit of 10 psi.... No.
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