What are the differences between wave generator and oscillator? (Specific design)

Discussion in 'General Electronics Chat' started by itayd100, Jan 30, 2016.

  1. itayd100

    Thread Starter New Member

    Jan 30, 2016

    I design the attached circuit:
    75 MHz Sine wave that connected to R and C in parallel

    The output, the amplitude of the sine wave, is changing according to the C, more capacitance smaller amplitude of the sine wave.

    When I tried that in the lab I got 2 results:
    1. When I connected the signal generator as an oscillator I got the same results - higher C lower amplitude (of the sine wave in the output)
    2. When I connected it to oscillator (http://www.farnell.com/datasheets/75480.pdf) I'm getting different result: the output is a sine wave, but if I make C higher the amplitude becoming lower until the sine wave (in the output) is "flipping" (kind of changing phase) and, if I keeping the C higher, the sine wave in the output getting higher

    What are the differences between the two?
    How can I make the oscillator work like the wave generator in this case?
    • gen.png
      File size:
      4.3 KB
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
    Its called Reactance, as the frequency changes the capacitor acts like a resistor in parallel and as the frequency increases its reactance gets lower, viceversa so it attenuates the signal.
  3. itayd100

    Thread Starter New Member

    Jan 30, 2016
    thanks for the answer. I know that called reactance, but why with the two setups I'm getting deference results? (same frequency, came C, same R)
  4. dl324

    Distinguished Member

    Mar 30, 2015
    What is the other setup?

    You mentioned trying this in a lab. Is this homework?
  5. itayd100

    Thread Starter New Member

    Jan 30, 2016
    The setups are like the photo in the first post with one difference between them: In the first one the oscillator is wave generator and the second is with IC oscillator (http://www.farnell.com/datasheets/75480.pdf).
    The lab - is room in my house with some equipment :)