Sinusoidal signal generator

Discussion in 'General Electronics Chat' started by samjesse, Dec 17, 2009.

  1. samjesse

    Thread Starter Senior Member

    Sep 14, 2008

    Please allow me to think a loud.
    If I have a coil "primary", pulse it with a square or saw tooth wave, then get another coil "secondary" near it, would not I get a sine wave out of the secondary coil due to the build/collapse of the magnetic field?
    If I play around with the physical orientation, put an iron rod in the middle of one, maybe turn one coil over the other, toroidal, or whatever, with the objective of making this sine wave pure.
    Is not this easily do-able? if not, why?
    Is not this who AC is generated? buy the moving interaction of a coil and flux?

  2. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
    This depends on the loading of the secondary, among other things. If you do this at the self resonant frequency of the transformer, with no loading, the transformer will give you a damped sine wave, which, if repeatedly excited, can give you a very clean sine wave on the output.

  3. samjesse

    Thread Starter Senior Member

    Sep 14, 2008
    OK, I need to chew on this a bit.

    Loading of the secondary:
    Is that the rate of flux density to the secondary coil metal volume?

    among other things:
    Maybe a link will help, google was not very helpful here.

    self resonant frequency of the transformer, with no loading:
    I thought resonant is in RLC, but now I hear something new about it in a transformer. which components juggle the potential vs. kinetic energy? primary vs. secondary coils? hummmm
    and with no loading? well, that makes my first question about loading sound subjective at least.

    more questions than answers till I do some home work. can you please provide a good link or two?

  4. Duane P Wetick

    Senior Member

    Apr 23, 2009
    Because of the nature of inductive coupling of 2 circuits, depending upon their orientation, you will have a time dependent mutual coupling of one to the other.
    Inductors by their very nature, do not respond well to steep wave fronts, so your square wave may very well produce a sine wave in a mutually coupled neighbor.
    See Inductance Calculations, ISBN 0486495779 by Professor Grover for more information.

    Cheers, DPW [ Spent years making heaters out of op-amps.]
  5. Ron H

    AAC Fanatic!

    Apr 14, 2005
    In an inductor, the flux is proportional to the current. If you apply a step of voltage to an inductor, you will get a ramp of current, because i=(1/L)*∫(v*dt). You will therefore get a ramp of flux. I don't think there is a way to get a sine wave, other than at resonance, as Eric said.