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Thread: Any one know how i can build a Step Up transformer?

  1. #1 Any one know how i can build a Step Up transformer? 
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    yeah, i've been known to make a lot of things just for the fun of it, but this one i am actually looking to make to supplements my plans on building a rail gun. i have 2 microwave oven transformers that i would use but i fear they may be AC instead of DC. i need a DC transformer because my rail gun circuts are already DC, and i dont really know a lot about AC.

    i usually look something like this up more exstensivley, but some form of virus has infected my searches on google and yahoo, so i am unable to effectively gather information about them.

    anyway, i just wanted to know if any one around here has any articles of info about how to make a DC step up transformer with simple tools and gadgets. by simple i dont mean tell me to go buy a $100 item just to butcher the insides of it for scrap.


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    A DC Transformer....I almost died laughing while trying to eat my dinner.


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    (In)sanity's right, there is no such thing as a d-c transformer. There are circuits, like in a camera flash, that step up d-c voltage. You can find them by googling camera flash circuit or something like that. I don't know how that would help your rail gun, though.
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  5. #4 Re: Any one know how i can build a Step Up transformer? 
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    Quote Originally Posted by slayer-72
    yeah, i've been known to make a lot of things just for the fun of it, but this one i am actually looking to make to supplements my plans on building a rail gun. i have 2 microwave oven transformers that i would use but i fear they may be AC instead of DC. i need a DC transformer because my rail gun circuts are already DC, and i dont really know a lot about AC.

    i usually look something like this up more exstensivley, but some form of virus has infected my searches on google and yahoo, so i am unable to effectively gather information about them.

    anyway, i just wanted to know if any one around here has any articles of info about how to make a DC step up transformer with simple tools and gadgets. by simple i dont mean tell me to go buy a $100 item just to butcher the insides of it for scrap.
    Usually they call them voltage doublers, quadruplers, ladders, or cascade voltage multipliers.
    You have to attach these to an AC source, like a transformer, either high or low voltage, and they will double, triple, quadruple the input AC voltage. Or multiply the input AC voltage by as many steps as you create in the multiplier.

    The bridge doubler is a sweet little device. I use four small diodes with low forward voltage drop.

    "V" escalation is also a form of voltage multiplier. It is simply two bars of metal, laid in a "V" formation. As the arc travels up the rails, it increases the voltage.

    This is some old information from Radio Shack, and Forrest Mims III



    You can get high voltage wire, and diodes on ebay at rather low prices. They have two amp 30,000 volt diodes. You can injure yourself with these devices though. So use care. If you shock your heart or cause it to stop. Laugh. It really makes it feel better. And unlocks it. If you blow a valve though, it is not that funny.

    As you get up in voltage you can get some pretty weird things happening. Sparks jumping to you. I have never been hurt by a spark jumping to me. It just shakes you up when you are working with your hands on high voltage components. Ha-ha. Just don't let it make you put your hand on something bad.

    I have had some DC arcs go around corners and find a gap in a Formica seam to get to ground. Using neon transformers and diodes.

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    William McCormick
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    I built these years ago.





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    William McCormick
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    The closest thing I can think of to take DC to higher voltage DC would be a pump charge capacitor system. It more or less charges a bunch of capacitors in parallel and then switches (rewires) them all to series.

    So if you charged say 100 capacitors @ 12 volts each and then switched them all to series you would have 1200 volts. These tend to be expensive and complicated at such high part count. I've built one to get to around 380 volts from 12 volts but ended up destroying a whole bunch of mosfets when I got the duty cycle all wrong. The timing from switching the caps to parallel and series has to be just right. For certain applications this could be pretty slow. Ohh and the circuit tends to draw a massive amount of amperage.
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    lol yeah, i looked some things up while no one had posted, and i found a way to use my two MOT transformers. thanks for all the help anyway guys.

    though i still dont know why you cant have a DC transformer. from what i've learned so far of transformers, shouldnt it be possible?
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    The basic reason that a transformer doesn't work with d-c is Faraday's law which states that the induced voltage is proportional to the rate of change in magnetic flux.



    With direct current, the current in the primary of the transformer is not changing, so the magnetic flux is not changing, so the induced emf in the secondary is zero.
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    Quote Originally Posted by Harold14370
    The basic reason that a transformer doesn't work with d-c is Faraday's law which states that the induced voltage is proportional to the rate of change in magnetic flux.



    With direct current, the current in the primary of the transformer is not changing, so the magnetic flux is not changing, so the induced emf in the secondary is zero.
    You can DC pulse a transformer, with one polarity only. It will create a single pulse in the secondary winding of the same polarity. And you can repeat that.




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    if you need to increase voltage, hook a bunch more batteries up in series....

    or you could get a capacitor,

    or just listen to William those output DC power.
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    if your using pulsed DC you can use a choke alone often in the form of a Boost DC-DC converter. It's interesting to note that this circuit shares many AC characteristics internally during it's oscillation process. As soon as you add inductance to a pulsed DC circuit you almost always end up with some current of the opposite polarity due to the flyback effect of the collapsing field. This of course is undesirable for most applications, in the case of the boost converter it's used to our advantage.

    Here is some information on a boost converter.

    http://en.wikipedia.org/wiki/Boost_converter

    One should also note that the flyback effect does occur if you DC pulse a transformer, you will end up with some AC current. Normally a diode would be used to clamp off the alternate voltage. It drives the efficiency of the process down. Failure to realize this flyback effect can result in many a damaged circuit. Some MOSFET drivers have this "flyback diode" built in.
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    William's post is very helpful in your case because you need a very high voltage and the cascade multiplier will be the right idea for a rail gun. It emits a high voltage pulse. A spark discharge of a sphere gap, or the electrodes of the rail gun will cause a chain reaction with all of the capacitors and discharge them all very quickly. You will need to have fairly large capacitors, both in capacitance value and physical size to handle the voltage requirements. The railgun will have to be able to propel the projectile through it's length by the time the capacitors discharge. This discharge will probably happen on the order of a few milliseconds.

    Warning: The larger the capacitance, the more dangerous the shock.
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