LED frequency circuit

Discussion in 'General Electronics Chat' started by electronice123, Dec 13, 2008.

  1. electronice123

    Thread Starter Senior Member

    Oct 10, 2008
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    I am trying to build a circuit which does the following.

    The circuit has a frequency generator which drives a transistor, the frequency generator is also needed to turn some LED's on when frequency is in it's off time.

    What I want to do is use 2 LED's which will alternate during the off time. I don't want both LED's to be on at the same time, but to alternate, and I need them to both alternate in the frequency generators off time.

    How do I do this?
     
  2. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Can you draw a timing schedual?
    Are the frequency generators truned off for a while?

    Greetings,
    Bertus
     
  3. electronice123

    Thread Starter Senior Member

    Oct 10, 2008
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    I don't know what the timing will be yet as the frequency generator has a PLL that locks the resonant frequency of the LC circuit.

    The circuit is gated every few pulses.

    I'm thinking I can take the frequency and multiply it by 4, then use logic and/or a counter to alternate the LED's, I'm just not sure how to do it?
     
  4. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    At what frequency will the generator work?
    When it is to fast you will not see the leds go on and off.
    What kind of PLL are going to use?
    Here is a link with a lot of PLL circuits.
    http://www.educypedia.be/electronics/pll.htm

    Greetings,
    Bertus
     
  5. electronice123

    Thread Starter Senior Member

    Oct 10, 2008
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    The circuit will operate at atound 10kHz, so I'm sure I won't even see the LED's. I am going to use a 4046 PLL.
     
  6. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    The 4046 has two phase comparator circuits.
    Which one are you planning to use?
    Do you want to see if the PLL is locked or not?

    Greetings,
    Bertus
     
    Last edited: Dec 13, 2008
  7. electronice123

    Thread Starter Senior Member

    Oct 10, 2008
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    0
    I'm not sure which phase comparator it uses.
    I'll have to look into it more and read up a bit.
     
  8. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Here is the datasheet from TI.
    It also shows how to see if the PLL is locked or not.

    Greetings,
    Bertus
     
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