precision pulse generator

Discussion in 'General Electronics Chat' started by karas, Jan 5, 2017.

  1. karas

    Thread Starter Active Member

    Sep 8, 2011
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    I have clk signal with frequency 100khz I need to generate another pulse at the positive edge of the clk for 1 micro second on and 9 micro second off ,can I use one shot timer or there is another idea more accurate.?
     
  2. dl324

    AAC Fanatic!

    Mar 30, 2015
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    Using a PLL to generate a 1MHz signal from your 100 kHz signal would let you generate the desired pulse accurately.
     
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  3. karas

    Thread Starter Active Member

    Sep 8, 2011
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    the signal I need to generate it will be 100khz but its on time 1 micro second.
     
  4. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
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    The PLL would generate 1MHz locked to the 100kHz, then use that as the clock for a '4017 decade counter. Any of the outputs from that chip will give you the signal you want - one cycle of the 1MHz high and nine cycles low.
     
  5. EM Fields

    Active Member

    Jun 8, 2016
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    How accurate is your 100kHz clock, how accurate do you need the width of the 1μs pulse to be, and how much delay can you stand between the rising edge of the clock and the rising edge of the 1μs pulse?
     
  6. dannyf

    Well-Known Member

    Sep 13, 2015
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    a capacitor + a resistor coupling to the 100KHz clock will do.
     
  7. crutschow

    Expert

    Mar 14, 2008
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    Need to know the pulse width accuracy you need, otherwise we are just guessing.
     
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  8. karas

    Thread Starter Active Member

    Sep 8, 2011
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    100khz+-1% and the 1 us=-10% ,and I need 1us every clk and is not important how accurate from the rising edge.
     
  9. karas

    Thread Starter Active Member

    Sep 8, 2011
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    1us+-10%
     
  10. crutschow

    Expert

    Mar 14, 2008
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    A 555 one-shot timer would be an obvious choice except they don't work well down to a 1μs period.
    Below is the LTspice simulation of a 74HC123 one-shot timer which should do what you want.
    The 74HC is fast enough to give a reliable 1μs pulse.

    The 5k ohm pot U2 allows adjustment of the pulse width to 1μs.

    Note that the unused inputs on the other one-shot in the package should be tied to ground.

    upload_2017-1-9_16-47-3.png
     
    Last edited: Jan 9, 2017
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  11. karas

    Thread Starter Active Member

    Sep 8, 2011
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  12. karas

    Thread Starter Active Member

    Sep 8, 2011
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    Thanks so much
     
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