help with a capacitor charger

Discussion in 'The Projects Forum' started by kirdaiht, Oct 15, 2009.

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  1. kirdaiht

    Thread Starter New Member

    Oct 15, 2009
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    hello.

    for a schoolproject I am using a capacitorbank. however, I have some troubles charging it. it cointains out of 8 350 volt, 1000 uF capacitors. unfortunately, our school can't provide me with a 350 volt powersupply. they do however have some other powersupplies which go up to 30 volts. I also want to have some kind of indicator which tells me when the capacitors are fully charged.
    Off course it is possible to take the charger circuit out of a disposable camera, but I could not get one of those. I also figuered it would most likely not survive decharging the capacitors.

    so my question is, can you help me with my circuite, if this is at all possible.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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    What might this be for? Those capacitors will carry a very lethal charge.
     
  3. russ_hensel

    Well-Known Member

    Jan 11, 2009
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    I would use 30 v or less, saves a trip to the cemetery. beenthere is dead on so to speak.
     
  4. kirdaiht

    Thread Starter New Member

    Oct 15, 2009
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    it is for accelerating small metal objects by use of lorentzforce.
    .we did try charging them up to 30 volt (even a little more since the actual voltage our supply delivers is a little higher)but it just didn't work. there wasn't enough power. I am also perfectly aware of the fact that these capacitors do not only kill you but also leave you with a nice brown crust if you decide to touch them on the wrong place.
     
  5. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    759
    If you are aware of the voltage level, u can always use an auto transformer with a line voltage level bridge.
    But Beware, u will be rectifying main AC voltage.
    Use an isolation transformer, but still be really careful.
    start with zero volts from the auto Tx, and use a voltmeter to measure the voltage rise at the CAPS terminal

    Rifaa
     
  6. t06afre

    AAC Fanatic!

    May 11, 2009
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    Theoretically if you charge a capacitor through a resistor. The current passing through the resistor will be zero then the capacitor is fully charged.
     
  7. SgtWookie

    Expert

    Jul 17, 2007
    22,182
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    Our Forums are very safety-conscious, and there are guidelines written into the Code of Conduct, posted here:
    http://forum.allaboutcircuits.com/announcement.php?f=6&a=3

    Bullet item 2, paragraph 3 begins:
    The project you are considering is commonly known as a "rail gun". There are great hazards in not only the potential energy stored in the capacitor banks, but also the possibility of injury and/or property damage caused by the kinetic energy of metal projectiles launched by such devices.

    Since such a project involves very real hazards, I would not think that it was an assignment by an instructor. If you attempted to bring such a device to a school, I would expect that you would wind up in a great deal of trouble for doing so.

    With all of this in mind, I suggest that this is not an appropriate board for discussion of such projects, and I would strongly recommend that you select another project that does not require more than 50v DC or 30v AC. This is for your safety as well as that of others.
     
  8. beenthere

    Retired Moderator

    Apr 20, 2004
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    This topic is against the safety guidelines.
     
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