how to multiply or divide frequency from 555

Discussion in 'The Projects Forum' started by pheonix992, Jun 23, 2013.

  1. pheonix992

    Thread Starter New Member

    Jun 23, 2013
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    I want to increase my frequency from 555 ic or decrease it
    but by small ration
    it means that I don't want to multiply or divide by number
    I want by fraction so please how ???????
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    I assume you mean a fixed frequency oscillator and not necessarily a 555 circuit.
    To multiply or divide by a small quantity you use a phase-locked loop.
    A vfo (variable frequency oscillator) is used plus divide by n counters in the path of the vfo and the fixed frequency clock. A signal from a phase comparator followed by a low pass filter is used to send an error signal back to the vfo.

    Google phase-locked loop.
     
  3. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    For small changes in 555 oscillator, put a pot in series with timing resistor. Multi turn pots seem to be more stable- from what I heard on AAC.
    More information would help with responses.
     
  4. pheonix992

    Thread Starter New Member

    Jun 23, 2013
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    I am making quadcopter without microcontroller
    and I don't now any source of frequency I can adjust manually
    except 555
    and what is pot ?
     
  5. MrChips

    Moderator

    Oct 2, 2009
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    Here is another example where I've been sent on a wild goose chase.
    You must tell us on the opening post what you are attempting to do.

    What does a 555 oscillator frequency have to do with a quadcopter?

    A "pot" is short for "potentiometer" which is a voltage divider which can be implemented with a variable resistor.

    Put a variable resistor in the 555 timer circuit to adjust the output frequency. You can do this to make both small and large changes in frequency.
     
  6. pheonix992

    Thread Starter New Member

    Jun 23, 2013
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    the quadcopter motor is brushless motor which need speed controller and its input
    is frequency range from 460hz to 1.63khz
    my problem is in the stability
    I already used 4x (555) for each motor
    so I use the accelerometer and I use it to increase gradually the frequency of the motor which need to increase its speed to make the copter stable
    that's my idea
     
  7. MrChips

    Moderator

    Oct 2, 2009
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    Are you controlling the 555 timer frequency manually or is this done by automatic control?
    If the latter, a variable resistor will not work in this situation. You would need a voltage controlled oscillator (VCO).
     
  8. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    What is the output of the accelerometers,[ tilt sensor? ] variable DC V or PWM, or other?? 555 frequency can be varied over a limited range by modulating pin 5, or wide range with an analog opto-coupler [ LED & light dependent resistor, LDR ].
     
  9. pheonix992

    Thread Starter New Member

    Jun 23, 2013
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    the output of sensor of accelerometers is analog and Tilt Sensor Module its output is short circuit or open circuit
    put I use one source of frequency to the esc of 4 motors
    but how to adjust the frequency for each motor
    and how I use vco I think by pot also
     
  10. pheonix992

    Thread Starter New Member

    Jun 23, 2013
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    should use 4 (555) for my 4 esc
    or I use one 555
    and the esc is controlled by frequency only or with the amplitude of volt of frequency too
     
  11. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    I think a frequency adjustment is not needed, you need a method to change the frequency to a triangle wave then use a quad comparitor to to create a pulse-width-modulation to drive each motor. The comparitor will monitor your sensor and your triangle wave generator to control the DUTY CYCLE that each motor will need to maintain position.

    A triangle wave may not be perfect because the transfer function you need may not be linear but it will be a good start for you.
     
  12. pheonix992

    Thread Starter New Member

    Jun 23, 2013
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    but esc need square wave I guess
    and I have new problem when I use one 555 for the 4 motor
    they don't rotate fast I cannot reach their full power
    but when I connect 555 with one motor only it works
    why ???????
     
  13. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    The comparators that GopherT mentioned ,compare the triangle wave to the sensor output and then give the result as a square wave.
     
  14. pheonix992

    Thread Starter New Member

    Jun 23, 2013
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    there is a pin in 555 its number is 5 and it is called voltage control to adjust the copter to right or left or any direction I
    will make switch to input volt to it and to adjust its stability the same thing I do from the output of analog accelerometer
    but now I tried to use one 555 it didn't fly the motors not fast enough
    then I tried four 555 for each motor and the same problem
    now I adjust z-axis by pot and x,y axis by input volt to pin 5 in 555
    is there is any other source of frequency without processor or micro control
    some one help me its my project in college
     
  15. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Is the test platform tethered with control & power supplied by umbilical cord?
     
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