Oscillator Problem!!

Discussion in 'The Projects Forum' started by emilj726, Apr 16, 2014.

  1. emilj726

    Thread Starter Active Member

    Oct 1, 2010
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    Hi,

    I am having problems with this oscillator circuit I have been working on. I am trying to adjust the hysteresis of the circuit based on R2 R3 and R4. But I am not even getting a square wave on the output. Is there something wrong with my circuit what am I missing here. Can anyone help?
     
  2. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    The gain-bandwidth product of the LM358 is only 1MHz, so the output won't be very square at high frequencies.
     
  3. ronv

    AAC Fanatic!

    Nov 12, 2008
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    The LM358 has trouble running at that frequency. Make the cap about 100X as big and see if that fixes it. If you really need it to run at 300Khz maybe a comparator would work better.
     
  4. emilj726

    Thread Starter Active Member

    Oct 1, 2010
    52
    2
    The waveform is just high its like 3.68V. Not even a waveform. I can use either a LM324 or LM393. But is the oscillator configuration ok though?
     
  5. ronv

    AAC Fanatic!

    Nov 12, 2008
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    Use the 393. It should work as drawn if it is wired right. Make R5 1k.
     
  6. emilj726

    Thread Starter Active Member

    Oct 1, 2010
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    Can I omit the 74hc14 for now?
     
  7. ronv

    AAC Fanatic!

    Nov 12, 2008
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    Yes you can.....
     
  8. emilj726

    Thread Starter Active Member

    Oct 1, 2010
    52
    2
    It works now. I am confused why it didn't before.
     
  9. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Perhaps you had a poor/wrong connection.
     
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