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Competition: High Voltage Power Supply

Discussion in 'High Voltage' started by DerStrom8, Jan 18, 2013.

  1. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    Nice story KISS :D

    I presume the host is going to protect the experiment from environmental factors such as small gusts of air, etc, since he mentioned it will be in a "controlled environment". I don't think that's anything we'll have to worry about.

    Regards,
    Matt
     
  2. throbscottle

    throbscottle Well-Known Member

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    I did something like this as a HV obsessed teenager - when trying to understand how TV LOPT drivers worked, in particular the "efficiency diode". Ended up being able to produce a very destructive fat purple/pink arc - had a lot of fun with that. Probably bathed myself in X-rays.

    Wish I could remember how it worked - was a simple circuit, ran rather hot I seem to recall, was self oscillating I think. It's worth remembering LOPT's have several windings, so there are various options for primary and feedback windings.
     
  3. tcmtech

    tcmtech Well-Known Member Most Helpful Member

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    I am more than just a little reluctant to participate. I work 60 hour weeks now, 12 hour shifts for two days and three nights, plus I no longer have my electronics workshop. When we moved the old house to make room for digging the basement for the new house I cleaned it out and put the torch to it once it was free from the house.

    Moving it and fixing it up would have been more work and cost than just building newer and bigger one which I have yet had time to work on this winter.

    That plus all of my electronics parts, supplies, fabrication equipment, and everything else other than a basic soldering gun and a few multi meters are packed up in boxes and in cold storage in main shop being my wife wont let me have any of that in the house.:(

    To be honest the $100 doesn't mean much for me either. I make more than that every week sleeping at work. :p

    So if anyone wants to take my concept and run with it go a head! I have no problem with it! ;)
     
  4. dave

    Dave New Member

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  5. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    Bump. Competition is open now, and closes in one month and two days.
     
  6. tvtech

    tvtech Well-Known Member Most Helpful Member

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    How are you doing Matt? I did try and kind of warn you. A friend and all.

    You know what I mean. And, coming from a TV background.....it will not happen. Tell the "host" to get lost. No matter who it is.

    Seriously. Otherwise.......you are going to end up with pie on your face. Instead of the "host". Not fair :(

    You don't want that.

    Regards,
    tvtech
     
    Last edited: Feb 1, 2013
  7. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    There's no call for that. There's nothing anyone can say or do that would affect me negatively in any way. This is supposed to be fun and educational. If people choose not to participate, it's their own loss.

    Don't think we don't have a plan B.

    Matt
     
  8. tvtech

    tvtech Well-Known Member Most Helpful Member

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    Now I am at a loss for words. Be very carefull.

    Stay well Matt

    Regards,
    tvtech
     
  9. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi guys,
    This Thread is for the HV Competition being Coordinated by DerStrom8, PLEASE keep the Posts on Topic.

    Moderation.
     
    Last edited: Feb 2, 2013
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  10. tvtech

    tvtech Well-Known Member Most Helpful Member

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    Hopefully on Topic still :confused:

    Don't be cross with me Matt. Looking after your Integrity here. If I cannot do that for you.....I am worth buggerall as a friend.

    Regards,
    tvtech
     
    Last edited: Feb 12, 2013
  11. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    Did not intend to be cross with you tvtech. My integrity is not at stake, but I appreciate your concern.

    Eric, thank you for your post. I think it was needed ;)

    Regards
     
  12. tvtech

    tvtech Well-Known Member Most Helpful Member

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    Settled :). I feel better.

    Regards.
    tvtech
     
  13. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hi,


    Just noticed this thread :)

    I have to say first that silent partners are not uncommon.

    Second, i believe Ian had the right idea when he suggested using TWO transformers instead of one to deliver more power due to the fact that one single transformer will overheat. This is very common in high power supplies. Using more than two would also be an option for increased power output.

    This thread reminded me so much of the early 1980's, when myself and several others worked on a simple design to kill flies. The garbage cans would often be loaded with garbage but the top left half on half off, so the flies became a problem. The design was very simple, an old flyback transformer and a single power transistor driver with oscillator (with smaller drive transistor). The output was enough to create an 1/8 inch spark that would zap the insect once they landed on the wire grid that was wired across the bottom of the chamber (every other wire was the opposite polarity. The spark could be seen entering the body of the critter and it would maintain the arc for a while until presumable part of the insect dried out. This time period could be a few seconds probably at most.
    Unfortunately we never measured any of the output parameters, like voltage, current, etc. And not sure what kind of TV the transformer came out of.

    A TV transformer isnt the best idea anyway as i think you've discovered. That's because if it came from an old TV you probably will have a hard time reproducing the product for someone else for example. There's no sense in designing a one off product when other people might benefit from it too, so it would be best to use a transformer that can be found without too much difficulty. Im not sure anymore, but i think the TV flybacks are not that cheap either right? (been a long time now since i've looked into the pricing on this stuff).

    Winding high voltage transformers is a little different than winding 12v transformers as im sure you know. The layers have to be separated carefully and leads run out carefully, so it has to be wound with great care really. Not sure if anyone would really want to do this except for the true aficionado.

    I had to laugh at the "paper size" specification too. That's the first thing i thought of too...how do we design something that can handle 600 watts and is paper thin. Spatial specs like that are always 3d. But i think the silent partner is flexible enough to accept almost any size within reason, size commensurate with functionality...the better it works the more acceptable the size.
     
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  14. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    Good post Mr. Al, thank you very much!

    I have no idea where the "paper thin" thing came in. I thought it was a joke, but some people seem to be taking it seriously. The thickness does not matter at all--only the length and width (8 1/2" by 11").

    The reason TV flyback transformers were suggested originally is because the Host already has some at his disposal. However, he is very flexible and will take any designs that use different types of transformers, provided they fit the criteria.

    Thanks for the on-topic post. It's much appreciated after some of what's been posted in this thread :rolleyes:

    Best wishes,
    Matt
     
  15. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hi there Matt,


    Based on your reply this might seem nit picky, but i assure you it is not. The paper thin (and surface mount) humor came about because of the size specification, which was more or less in 2d (two dimensions). Since we live in 3d we would normally need a 3d specification. For example, an 8x10 piece of paper is 8 inches wide and 10 inches long, but only less than 1mm when laying flat on a flat table. So the design would have to fit within that volume, which as you can see is not very much.

    Or taking it the other way, the width is 8 and the length is 10, and the height can be anything...so that means we can design a circuit that is 8 inches wide, 10 inches long, and 20 feet high. Nice, as that gives us plenty of space for a high wattage product :)

    What i think you had in mind though was that the 'pc board' was to be 8.5 x 11 inches. The only problem here is that we are dealing with a possible high power circuit, which often needs largish heat sinks. So some specification on the height would be in order too. With today's components though it may be possible to lower the size of the heat sinks, but the transformers may still require a significant portion of the package size.

    If i had to guess, i would think again the size would be commensurate with the functionality.

    Again, not trying to nit pick just trying to feel out the limits.
     
  16. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    Hi Mr Al--

    I understand compltely. To my knowledge there isn't a height specification, provided the overall size is reasonable. Obviously 20 feet is a bit over-the-top, but I think the builder can make reasonable decisions as to the thickness/height.

    As for the transformers and heat sinks, I was thinking I mentioned somewhere that they are not to be counted in the size of the overall design. The circuit itself should fit on a sheet of standard letter paper, but the transformers, power supplies, heat sinks, etc are set aside from the rest of the design, and are not considered under the size constraints. However, they do still need to be reasonably lightweight.

    I hope this helps clear up some of your questions.

    Best wishes,
    Matt
     
  17. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hi Matt,


    Yes that seems good enough. I kind of assumed something reasonable would be accepted, but it's nice to know the actual limits just in case this thing has to fit in someone's small space which cant be expanded because of other constraints.
    Was the weight mentioned before this? That's a good point too.
     
  18. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    PS; Don't mind me, I have just been the Devil's advocate. Dotting i's and crossing T's, I guess. Maybe one day we'll have atomic thick circuits. I could be really wierd and ask, can anyone bury components within the PCB (possible now) to reduce the size? Ignore that. Having worked on a few HV, High current power supplies, the control circuit PCB in this particular one was basically 6" x 8". Just to support the regulator, you had a box 2' x 2' x 2' an casters etc. The interlocks, deflection etc, was handled by a separate 4RU case. I remember that the voltage divider was a string of about 6 or eight 625K, maybe 20-50 W resistors in series. The rectifier's were physically big and they also needed a few in series. Then you needed clearances just for the HV. Operator keys and control cabinet keys were also required. Very limited access to the HV area except by key. 30 kW, was a BIG supply. The HV was 15 KV at 1.5 Amps or so. Before this supply, I had never seen a three phase primary, single phase secondary transformer before.

    The other one was wierd, from the 1940's open nearly everywhere. The back was toward a wall, totally open. The oil filled transformer was about 2' diameter and 16" tall. It had to supply 100 kV at 0.1 A max.

    I should be devil's advocate again and ask "What if any protective features have to be incorporated?" Examples:
    1) Should survive being plugged into a GFI socket
    2) Over temperature shutdown
    3) You discussed, I think current limiting.
    4) Bleeder resistor?

    The list above is by no means exhaustive but I would consider it minimal. Other required interlocks, such as physical, would come after this phase.
     
  19. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    Yes, I believe it was. I'd have to go back and look for it though.

    EDIT: Found it. It's in the updated criteria listed in Post #92. Design weight should not exceed 3 lbs.

    Any extra features will gather favor in the judging. If you can incorporate any of the above features, on top of the basic requirements, your design will be given extra points. It's as simple as that :)
     
  20. tcmtech

    tcmtech Well-Known Member Most Helpful Member

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    So has anyone officially submitted anything yet? :confused:
     
  21. RODALCO

    RODALCO Well-Known Member

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    Interesting thread, just read through all the replies.
    My experience with LOPT is that they do overheat very quickly at higher currents.

    I have built a few ZVS drivers with IRFP250 mosfets (in 2-2 parrallel) , which can switch at 36 Volts 11 Amps to a LOPT with no problems.
    Drive current through 5 + 5 turns wound over the ferrite.
    Arcs up to 10 cm can easily be made in open air, most likely a lot bigger in a vacuum.
    Pushing 400 Watts out of a LOPT will heat them up in about 1 to 2 minutes.

    For portability this set up is not ideal. I use SLA's to supply the current.

    Happy to post some pics if someone is interested.
     

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