Basic coil help for an idiot

Discussion in 'General Electronics Chat' started by kenw232, Feb 27, 2011.

  1. kenw232

    Thread Starter Active Member

    May 18, 2009
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    I have a normal coil. I'm going to send a clean 22V @ 1A square pulse into the coil. whatever frequency, say 2 hertz. So the coil will charge and discharge every two seconds.

    If I scope the coil it will look like <snip>. How can I keep the integrity of the square pulse high, like if I scope the coil the waveform will look like <snip>. I'm trying to keep the pulse going in (and coming out) as clean as possible. Any tips for a novice? I need to bridge the connectors of the coil with a diode to stop the back emf from discharging back into my circuit right? any recommendations on the proper diode for that? Just seems the more I pulse the uglier the square wave becomes. Maybe I'm not suppose to put the coil on the scope directly, should have a resistor?

    Sorry my question is kind of obscure.
    Thanks.
     
    Last edited by a moderator: Feb 27, 2011
  2. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    Post your schematic, also what's the purpose of the circuit?
     
  3. Jaguarjoe

    Active Member

    Apr 7, 2010
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    Current, lotsa current!
     
  4. kenw232

    Thread Starter Active Member

    May 18, 2009
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    I don't really have a schematic. Its just an n-channel MOSFET turning on and off a car battery. works well to light a bulb. straight forward, the bulb flashes because my freq gen is controlling the mosfet with a square wave.

    I now want to take that current from the car battery and put it into a coil to create an oscillating EMF field (for experiements and general craziness). I would like to keep the square wave as structured as possible in the coil as it charges and discharges. Like no high voltage spikes or distortion on the edges of square waves. Anything a novice needs to know?
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    I think that you need to study up on how inductors work.

    Inductors resist a change in current. They're sort of like automobiles or railroad trains in that regards. You might stomp down on the loud pedal, but it takes them a good while to get up to speed.

    Once they're moving along, they like to stay moving along - like the current in an inductor. Ever try to stop a train suddenly? Ever hit a concrete wall with a car? Not a pretty sight. A similar sort of thing happens with an inductor when it's circuit opens; the current tries to keep flowing in the same direction, but it can't - so the voltage across the terminals reverses and builds to a very high voltage peak. If you've planned for that eventuality, no damage is sustained, and the excess voltage is bled off before it can do damage. If you didn't plan for it, you'll punch holes in things.
     
  6. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    Ok I'll bite, why do you think you need a square wave? What is the goal of your project?
     
  7. kenw232

    Thread Starter Active Member

    May 18, 2009
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    right, I need to plan for this stuff. so what is the best diode to stop this backemf voltage spike. any zener will do? I noticed too as I pulse the coil I get an overshoot like in my attached screenshot (I just thew this together to make a point, its not very good). how do I clean up stuff like this?
     
  8. kenw232

    Thread Starter Active Member

    May 18, 2009
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    Just to learn how to create waveforms, and more powerful waveforms without loss of integrity.
     
  9. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    But for what use? You seem to have specific details 22V @ 1A, 2Hz Square wave. Where did you get these numbers? Why are they important?
     
  10. kenw232

    Thread Starter Active Member

    May 18, 2009
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    I just made it up. I'm working with a bunch of variations of those numbers. I eventually want to increase the Hz in the coil while maintaining waveform integrity, seems the wave breaks down once Hz gets too high. its just for learning and whatnot.
     
  11. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    I was worried it was another one of those Bedini motor idiotic projects. Like SgtWookie said earlier you need to read up on how inductors work.
     
  12. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    Joy! I have a better guess, a Rodin coil.

    It's smoke and mirrors, utter BS, snakeoil... The only thing Marko Rodin has invented is a way to get money from fools. His site is pure nonsense, good for a laugh and hypnotic doodles.
    Do I get a prize!
    http://www.rense.com/RodinAerodynamics.htm
    [​IMG]
    I'm hypmotized!
     
  13. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    What your asking is similar to wanting something almost impossible to achieve.

    The nature of physical structures known as an inductor DOES NOT ALLOW SUDDEN CHANGES OF CURRENT.

    This will ALWAYS cause a rapidly changing current to be LESS rapid. In other words it will put more slope on the rising edge of your square wave

    NO MATTER WHAT YOU DO.

    Please read up on the physics and uses of inductors.
     
  14. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    The answer was a Rodin coil.
     
  15. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    I can usually smell an overunity project from a mile away, they stink like moldy cheese.

    And in the off chance that Mr. Williams reads this:

    Overunity, HHO, Bedini motors, Rodin coils are all scams. They all violate at least one law of thermodynamics. The "inventors" are often uneducated hicks with just enough skills to connect a bag of wires to some coils and a motor (and there's always a battery nearby) and post some useless YouTube video. They're also either outright liars / scammers or poor fools who've convinced themselves they're just that one step away (reality) from overunity greatness (illusion)

    Summary, overunity will never ever happen. You always need more energy in then you'll ever get out.

    PS the Rodin guy is just plain nuts.
     
    Last edited: Feb 28, 2011
  16. kenw232

    Thread Starter Active Member

    May 18, 2009
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    Thanks blueroom, your insight is priceless.
     
  17. russ_hensel

    Well-Known Member

    Jan 11, 2009
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    It is not possible. You can have 22v or 1 amp. Not both all the time ( the square wave is high ) Read up on inductors.
     
  18. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    You've used the same user name all over the net, wasn't difficult.

    Well was I right or wrong?
     
  19. kenw232

    Thread Starter Active Member

    May 18, 2009
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    ok, I'll read up on inductors I guess. Not sure why I can't have a 22V potential difference moving at 1 amp. The square wave is high? Any clarification would be welcome.
     
  20. kenw232

    Thread Starter Active Member

    May 18, 2009
    54
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    I cross post to get more replies. what do you want from me? do you want me to say I'm making a rodin coil or something?
     
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