Quick Inductor question

Discussion in 'General Electronics Chat' started by MusicTech, Apr 17, 2008.

  1. MusicTech

    Thread Starter Active Member

    Apr 4, 2008
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    I know capacitors discharge very quickly, dangerously if they have enough voltage. Do inductors behave the same way, or does that determine to much on the resisitivity (the natural resistance of an object to lose charge, just in case I am using the wrong word, in which case I probably am) to give a solid answer. Thanks.
     
  2. Caveman

    Active Member

    Apr 15, 2008
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    Inductors actually do something similar (but different). A capacitor discharges quickly if you try to make its voltage equal to zero instantaneously. The way that it 'resists' this is by supplying a lot of current.

    An inductor doesn't want the current to change instantaneously. When you try to do this, it will generate a large voltage across itself trying to maintain voltage. Voltages can get quite high and even destroy parts, cause arcing, etc.
     
  3. thingmaker3

    Retired Moderator

    May 16, 2005
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    Both capacitors and inductors will discharge or charge more slowly as series resistance increases. Both use the same logarithmic curve. It is a voltage curve for capacitors (which store energy in an electric field), and a current curve for inductors (which store energy in a magnetic field).

    The universe hides its beauty in unexpected places.
     
  4. DC_Kid

    Distinguished Member

    Feb 25, 2008
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    i wouldnt say a inductor "stores" energy only because for the mag field to sustain there needs to be active current flowing. a cap on the otherhand will remain charged after pulling it from the potential it charged from.

    the fundamentals of voltage and currents in caps and inductors are basic phase shifts as to when a instrument "sees" each during a event (charge or discharge). if i recall correctly for DC the phase shift between voltage and current is 90 degrees for each component. in a inductor voltage comes before current, and in a cap current comes before voltage. phase will change with frequency.
     
  5. Wendy

    Moderator

    Mar 24, 2008
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    Actually you are incorrect. In the case of superconductors an inductor will store it's energy indefinately if you close the loop. The difference between the cap and the coil is the current has to be moving in the coil, remove the losses and it can do the same things.

    Inductance and capacitance are mirrors of each other, literally. Ever wonder why LC circuits are so necessary for electromagnetic radiation?

    And for my next trick, we will discuss time warps.
     
  6. Caveman

    Active Member

    Apr 15, 2008
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    Actually, an inductor does store energy, we just can't make them well enough to get rid of the leakage of energy via the resistance. This is simply because practically we can make huge resistances easily which helps caps not drain, while very low resistances which help inductors not drain are very difficult to make.

    The exception is superconductors. superconducting coils connected in a loop can have current injected into them, and store the energy for a long, long time.
     
  7. nomurphy

    AAC Fanatic!

    Aug 8, 2005
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    To answer your question: yes, they can behave in a similar fashion and one should take similar cautions whenever around storage devices capable of high voltages or currents (although you won't be able to charge a coil and toss it to somebody while saying "catch" with quite the same effect as with a capacitor).

    For instance, there are specific ways to discharge the hi-voltage from the flyback transformer on a TV set BEFORE working inside the set. Many have felt Mr. Coulomb's wrath by not abiding that rule.
     
  8. MusicTech

    Thread Starter Active Member

    Apr 4, 2008
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    haha very true. maybe I should get an inductor and study, I will use my hand as a conductor to connect the two leads, I assume the best way to do this is use the the coil with most amount of turns, right? ha
     
  9. SgtWookie

    Expert

    Jul 17, 2007
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    Absolutely - with a guy standing on the other side cranking a funny-looking handle. :eek: :D

    (0blique reference to the old military field telephones - they had a hand-cranked generator to ring the bell on the other end - if someone was holding the wires instead, they got their bell rung pretty good ;) )
     
  10. Papabravo

    Expert

    Feb 24, 2006
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    "Let's do the time warp again!"
    -- Rocky Horror Picture Show
     
  11. Wendy

    Moderator

    Mar 24, 2008
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    I've always heard it was a good emergency fishing technique, drop wires in water with weight, crank handle, collect floating fish...

    Not sporting, but nutritious.

    Sarge has a website that shows how to use the coils energy to create high voltage from a current. I used to do something similar with a simple relay wired as a buzzer. Used this way it is called a flyback transformer. I've been known to call it a tingler, it is used in a lot of gag props, like books with metal covers and catchy names like "Excite Your Life". Note: This was my way of getting the thread back on track after highjacking it.
     
  12. beenthere

    Retired Moderator

    Apr 20, 2004
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    Word of caution here. I used to build the electrofishing equipment for the state. If you have anything near a body of water with fish in it that can put a charge into that water, it's a "go to jail" card. State fish and game agents are very knowledgeable about any such gadget, and will never give you a pass on finding one.

    I you have to examine the effects of electronarcosis, do it to your goldfish.
     
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