retriggerable monostable. could you help me?

Discussion in 'General Electronics Chat' started by johnal2, Aug 21, 2014.

  1. johnal2

    Thread Starter New Member

    Aug 11, 2014
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    Hi All
    a week ago, I posted "I have a 12v circuit and it has a LED that is flashing repeatedly in a normal output. I want to make a new circuit that detect this flash and turn it into a normal on light or (motor run). If my circuit LED stops flashing, then the light or (motor) would turn it off."
    I tried the CD4047BE from http://www.electroschematics.com/6013/retriggerable-monostable/. it is very easy to make with 2 resistors and a capacitor 0.1uf. However, signal in but no signal out... Thanks
     
  2. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    "If my circuit LED stops flashing, then the light or (motor) would turn it off."

    This part does not make sense to me.
     
  3. johnal2

    Thread Starter New Member

    Aug 11, 2014
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    Hi Shteii01
    If the first signal circuit broad LED light flashing... the second circuit (maybe missing signal detector or retriggerable monostable circuit this is what I want to make circuit) would turn the motor or light on. If my first circuit LED light stops flashing, the second circuit control retriggerable would turn the motor off. Thanks
     
  4. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    What's the input to your circuit?

    Ken
     
  5. johnal2

    Thread Starter New Member

    Aug 11, 2014
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    Hi Kmoffett
    My input is from the PIC16F1826 LED signal to the cosmo1010 then I connect the c terminal from cosmo1010 to the retriggerable with or with out a capacitor.
    Thanks
     
  6. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    It sounds to me, overall, that you are trying to use opto isolator. Only instead of calling it opto isolator/using actual opto isolator you are using LED and some kind of light detector. Would it be helpful to you to just use opto isolator?

    Second thing. Motor control. The flashing LED reminds me of PWM signal. Do you realize that you are trying to control motor using PWM signal? Do you realize that when LED is Off, the motor will be Off so there is no need for other "stuff". Well... ok, you might need an H-bridge circuit for the motor.

    So far the simplified circuit looks like this, to me:
    uC-->opto isolator-->opto isolator signal conditioner circuit-->motor/motor circuit
    It seems pretty straight forward.
     
  7. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Stare at this...


    [​IMG]
     
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  8. johnal2

    Thread Starter New Member

    Aug 11, 2014
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    Hi Shteii01
    The problem is that my first circuit signal from the PIC16F1826 is a repeated cycle and therefore, direct output will be on and off and on and off repeating. I want to make a circuit to receive this signals and converse it to on only... then if the signal is turned off then the motor will be off too. Thanks
     
  9. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    So hook the relay and diode between the OUT pin of the 555 and ground.
     
  10. johnal2

    Thread Starter New Member

    Aug 11, 2014
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    Hi Mike ML
    I got hold of a CD4047BE and forgot about your 555 circuit. I will try to built this this weekend. Thanks
     
  11. johnal2

    Thread Starter New Member

    Aug 11, 2014
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    Hi MikeML
    I just finished the circuit above "Missing pulse detector; however, Output terminal #3 to Vcc+ is always on i.e. Light is always on if I put the relate then the relay is always on regardless of input signal or even completely no input signal the light or relay is always on.. (ICM7555 or 7555 IPA)
    Thanks
    Kyle
     
  12. johnal2

    Thread Starter New Member

    Aug 11, 2014
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    Hi MikeML
    the capacitor 100n is that the 104 capacitor?
    Thanks
     
  13. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    104=10n=0.01u
    105=100n=0.1u
    106=1000n=1u
     
  14. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    What is the voltage on node "rc"? (Pins 2, 6)?

    The CMOS version of the timer you are using can only source and sink 20mA on pin3, so it will have a hard time driving a relay. The NE555 (bipolar) version that I assumed you were going to use can source and sink 200mA.
     
  15. johnal2

    Thread Starter New Member

    Aug 11, 2014
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    Hi MikeML
    I will find the two capacitors 105 and buy a new LM555 from Radioshack today. 12v power input. I can't remember on the 2,6 pin but I will check it after work.
    Thanks you very much.
    Kyle
     
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