100V output power supply

Discussion in 'Electronics Resources' started by algio, May 29, 2011.

  1. algio

    Thread Starter New Member

    May 29, 2011
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    0
    Hello,

    I am interested in having a fixed 100V output power supply. It does not matter if it is not very stable. I would need about 50W power output (500mA).

    I did a lot of searches in the web and I could not find any ready to buy. Anyone knows any? In principle I would like it with 230Vac input, but a DC input (i.e 5 or 12V) could also work.

    Thanks
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    You could perhaps do this with TWO adjustable bench supplies capable of 60V output each. Adj. them to 50 Volt and then loop the positive output of the first to the negative output of the second. Several checks at much lower voltages would have to be made to insure the circuits were capable of being driven on a boosted DC level. Probably would have to insure the cases did not touch as well. Some reason you don't want to create the traditional transformer to rectifier style DC supply?

    Search google for DC to DC power convertors to find chips and example circuits for boosting 12VDC to higher voltages. These would not likely give more than a few milliamps however.
     
  3. someonesdad

    Senior Member

    Jul 7, 2009
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    Such supplies are not as common as they once were; one of the main reasons is solid state electronics replaced tube-operated stuff (supplies like you want were much more common 40 years ago). But all is not lost -- you can look on places like ebay to find such things. Another possibility would be to go to a local college's engineering and physics departments and see if they have an old supply they'd be willing to sell.

    I have a number of DC power supplies and when I need such voltages, I connect them in series as Kermit2 suggested. To be on the safe side, check the manual to see if there are any limitations in doing such things.

    There are a gazillion bench supplies that you could use to do this (here's one). You don't give any specs on ripple, regulation, need for adjustable current or voltage, cost, etc., so until you get more specific, this is at least a start.

    I also suggest that you describe what you're trying to do and why you're trying to do it. You may find that there are better ways of getting where you're trying to go.
     
  4. algio

    Thread Starter New Member

    May 29, 2011
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    I plan to use this voltage to feed some fotosensors which require few miliamps, but since every photosensor may require a different voltage I plan to use after the power supply a TL783 regulator (http://www.datasheetcatalog.org/datasheet/texasinstruments/tl783.pdf) for each sensor to regulate the voltage. This is the reason why I do not really mind the ripple, regulation, etc of the power supply, because the regulator will do the job later.
    I have some restrictions for the power supply in terms of space (aproximately 5cmx5cmx5cm) and I cannot use a bench power supply.
    I prefer to use an already made power supply which accomplish EMC regulations, so that I will not have to worry about this. The other option would be to create the traditional transformer to rectifier style DC supply (as Kermit2 suggested) but I do not find appropiate transformers: the most common ones are from 230VAC to 120VAC, but if I rectify and filter the 120VAC I guess that since the peak voltage provided by the transformer is 170V it will dissipate too much power (maybe I am wrong, since I am not familiar with designing rectifier style DC supplies...
     
  5. t06afre

    AAC Fanatic!

    May 11, 2009
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    Take a look at the lm723 datasheet. You will find some design examples for your voltage needs. And the LM723 is a cheap IC.
     
  6. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    @ t06afre , the LM723 can me used to an input voltage of about 40 Volts.
    The OP wants to make a powersupply with 100 Volts output.

    @ OP, when you use a transformer with an output of about 80 Volts, the rectified and smoothened voltage will be about 110 Volts.
    This can be fed to the TL783, giving a voltage difference of 10 Volts as headroom.

    Bertus
     
  7. t06afre

    AAC Fanatic!

    May 11, 2009
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    And what do you base that on friend. I grow up with the LM723, and have used it in many apps. I said what I meant, and I meant what I said;).
    Read the datasheet once more. One of the best is this one http://www.st.com/stonline/products/literature/ds/4553/lm723.pdf Refer to table 6........ As you see you can build a circuit with the LM723 that will give 100V
    Eh..by the way this is no big deal. Your work in this forum Bertus is very good 99.99% of the time
     
  8. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    OK I see what you mean.
    I am not very impressed by floating powersupplies.
    There can be troubles with the shortcircuit condition.

    [​IMG]

    Bertus
     
  9. algio

    Thread Starter New Member

    May 29, 2011
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    0
    "when you use a transformer with an output of about 80 Volts, the rectified and smoothened voltage will be about 110 Volts."
    This may be a good choice! Thanks

    Also the LM723 may be good! Also thanks

    I am also evaluating the option of using the ltc3813 to provide the 100V. With this I can use a commercial power supply and I can forget about EMC regulations.

    I have the dream of producing the desing and trying to sell it in Europe (lets see!), and I have two doubts:
    1- In case I want to sell the power supply I guess I have to have in mind EMC and HV safety regulations, right? Who has to certify that? Can I do it myself by following some procedure tests?

    2- Is 100V dangerous voltage for people? (I guess yes, because it is above 50V). In what degree this voltage is dangerous? I guess also depends on the current (I plan to have several outputs of 50mA). Anyone knows from where I can get more info about it?
     
  10. bertus

    Administrator

    Apr 5, 2008
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  11. #12

    Expert

    Nov 30, 2010
    16,261
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    There is another way to float a 723. You use another winding like, 24V center tapped to make a supply just for the 723 chip. The center tap is connected to the output terminal so the entire winding floats on the 100V output. If anything shorts, the output collapses and the 723 supply falls toward ground with it.

    Does this sound better to Bertus?
     
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