Connect with us

Capacitors...Again

Discussion in 'General Electronics Discussion' started by Muhasaresa, Feb 9, 2012.

Scroll to continue with content
  1. Muhasaresa

    Muhasaresa

    45
    2
    Jan 2, 2012
    Hi everyone :D

    I'm afraid its another capacitor question from me....:rolleyes:

    I have a 555 square wave of around 1000 - 2000 hz (controlled by a potentiometer) that go to some speakers. Between the 12V and Ground I have a 470uF capacitor. When it is there, and when I turn the potentiometer handle, there is a nice smooth transition between the tones.

    However, when I rip the capacitor out and vary the potentiometer, the difference in tones are CHUNKY and only change to a few fixed notes (musicians: it actually is a minor arpeggio!).

    Why is there such a massive difference? Is it something to do with them smoothing out fluctuations?

    Thanks for the help,

    Muhasaresa
     

    Attached Files:

  2. GreenGiant

    GreenGiant

    842
    6
    Feb 9, 2012
    it seems that the 12V source is not a very clean /constant voltage

    The cap is just helping keep it a smooth constant voltage, and eliminating noise

    Just out of curiosity why do you want to rip out the capacitor?
     
  3. Muhasaresa

    Muhasaresa

    45
    2
    Jan 2, 2012
    I am sorry I just realised I made a typo: I am using a 9V battery to power the system, but even so there should not be such an enormous fluctuation to affect the tone so much.

    When I say I "rip" out a component, I just emphasise that I take it out of the circuit :D

    I have attached a diagram to illustrate exactly what the problem is:
     

    Attached Files:

    Last edited: Feb 9, 2012
  4. GreenGiant

    GreenGiant

    842
    6
    Feb 9, 2012
    that is a little weird, I still think its just a voltage fluctuation from when the timer and the resistor and the speaker draw from the battery

    Thats the best answer I can give you
     
  5. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    The (8 ohm?) speaker probably represents a very heavy load for the "super heavy duty" transistor battery (?) you're using.
    The rapid and large fluctuations you then get in the supply voltage to the 555 upsets its voltage-dependent timing circuit.
    If you had used a high-impedance speaker &/or an alkaline battery you would not have noticed any difference with or without the capacitor.
    The presence of the capacitor negates the (high) internal series resistance in the battery, on a short-term basis (milli-seconds).
     
  6. Rleo6965

    Rleo6965

    585
    9
    Jan 22, 2012
    Why don't you have capacitor connected to pin2 of 555 to gnd? Tis is suppose to be astable oscillator. Right?
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-