how to this build this circuit which uses oscillator and amplifier

Discussion in 'General Electronics Chat' started by PG1995, Aug 19, 2011.

  1. PG1995

    Thread Starter Active Member

    Apr 15, 2011
    753
    5
    Hi

    It would really kind of you if you could help me to build the circuit which does what has been explained in the linked diagram below. I'm new this stuff. Have never used oscillator or an amplifier. If you want to change some parameter to make the circuit simple, then you can. Thank you.

    the diagram: http://img89.imageshack.us/img89/3427/invercrkt.jpg

    Best wishes
    PG

    PS: I just made that block diagram up. You could any other frequency instead of 5 Hz. Thank.
     
    Last edited: Aug 19, 2011
  2. praondevou

    AAC Fanatic!

    Jul 9, 2011
    2,936
    488
    You will need an oscillator e.g. like THIS
    If you want to use an PWM-inverter that's also possible but the circuit will become MUCH bigger.

    Then you need a fullwave rectifier e.g. like THIS (pic 12.37)

    After this you pass the signal through a non-inverting amplifier, with an opamp for example. Yes the amplifier could also "de-amplify", if it's gain is set to less than 1.
     
    Last edited: Aug 19, 2011
  3. Adjuster

    Well-Known Member

    Dec 26, 2010
    2,147
    300
    It may help to begin by sorting out a bit of terminology: The word "inverter" generally means a device for turning DC into AC, usually working at a relatively high power level. This is the kind of thing that might be used to power AC equipment from a storage battery during a power cut. A device which only produces a low-level AC signal (for instance used to drive an amplifier) would normally be called an oscillator. Power inverters do not usually consist of an oscillator followed by a linear amplifier: such an arrangement is possible, but would not be very efficient.

    In your block diagram, your oscillator appears to be producing something like an un-smoothed full-wave rectified DC signal (at 5hz!!!), which is then amplified two times. This seems an odd requirement: do you really want this, or did you just make it up at random?

    In answer to your questions:

    1) To do this with analogue circuitry would require something like a Wien bridge or phase-shift oscillator, to give you as a sine wave. Inductors and transformers get difficult at such low frequencies, so LC oscillators are probably out of the question. Note that at such a low frequency as 5Hz, you will probably not be able to use the little light-bulb sometimes suggested as a level stabiliser.

    A precision rectifier circuit using op-amps would probably fit the bill for rectifying the sine-wave. This link may give you some ideas:

    http://www.physics.udel.edu/~nowak/phys645/More_opamp_circuits.htm

    2) A feedback amplifier can be designed to have a voltage gain of less than one. http://www.electronics-tutorials.ws/opamp/opamp_5.html
     
  4. PG1995

    Thread Starter Active Member

    Apr 15, 2011
    753
    5
    Thank you, Praondevou, Adjuster.

    @Adjuster: Special thanks. Your post was very helpful.

    I was simply playing around. Truth be told once again (although I have already told it in first post above) that I have never used an amplifier or an oscillator. You can change some parameters such as frequency, you can change amplification gain to any other number (the gain used by me is "2"). If someone of you have MultiSim, then can you build that circuit up so that I can understand its working by asking follow-on question? Thank you.

    Best wishes
    PG
     
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