I need help. 12v LED flashing

Discussion in 'General Electronics Chat' started by johnal2, Aug 11, 2014.

  1. johnal2

    Thread Starter New Member

    Aug 11, 2014
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    Hi Anyone

    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.

    Thanks

    John Al

    <SNIP>
     
    Last edited by a moderator: Aug 11, 2014
  2. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Wrong forum!
     
  3. johnal2

    Thread Starter New Member

    Aug 11, 2014
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    Hi Alec
    This is my first post. You said it a wrong forum? Could you help me where can I get help?
    Thanks
    John
     
  4. inwo

    Well-Known Member

    Nov 7, 2013
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    He may mean that it sounds automotive.:( Not allowed!

    There are some similar threads on here. Do a search.

    If they are automotive, they have been closed.

    If it's a non-automotive general question, seems you could find an answer here.
     
  5. johnal2

    Thread Starter New Member

    Aug 11, 2014
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    Hi
    I am new here. It is not for fixing automobile. I am trying to find any circuit that will turn on my toy. I looked into the LM555 and LM741 but i can't find any that has a LED input 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 had tested and used cosmo1010 but unsuccessful.
    Thanks
     
  6. inwo

    Well-Known Member

    Nov 7, 2013
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    Do you want to wire to the led circuit or detect the light?
     
  7. MikeML

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    Oct 2, 2009
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    Is the LED a self-flashing one, or is it being flashed by the upstream circuitry?

    Do you have access to tack-soldering two wires to the anode and cathode of the LED?
     
  8. Externet

    AAC Fanatic!

    Nov 29, 2005
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    Search for "missing pulse detection" and photo electric input for that circuit.
     
  9. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    The basic building block for this is called a retriggerable monostable. Comes in an IC package, one of many logic devices out there.

    Something like a CD14538 should work. You still need a detector for the input and a driver for the light or motor output.

    And do take your email out of your signature, unless you need more spam in yuor inbox.
     
  10. johnal2

    Thread Starter New Member

    Aug 11, 2014
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    Hi Mike
    It is from the circuit provide electric to the resistor of 89ohm to the LED diode. Thanks
    To Externet. I did tested the PWA and missing pulse from LM555 like this one [/QUOTE][​IMG]
    However, when i turned off the circuit of signal. the new circuit light still on unless I cut the power supply. This is not what I am looking for
    I am looking for
    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.
    Thanks
     
  11. MikeML

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    Oct 2, 2009
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    Any idea what the existing flash rate is?
    Any idea what the duty cycle is (how long the LED is on)?
    What is the battery voltage for the whole system (assuming you want to use it to power your light/motor)?
     
  12. MikeML

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    You will have to adapt this to your flash rate, flash duration, and supply voltages...
     
  13. adamclark

    Member

    Oct 4, 2013
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    could you not just use a photodiode to trigger the motor when the led stops?
     
  14. johnal2

    Thread Starter New Member

    Aug 11, 2014
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    Mr. Ernie. How can I remove my email (sorry first time member). I will try to buy the CD14538 and try it today if I can.
    Main question, Would it turn off the light or motor if the signal is "off" from my LED? I got the input from the resistor that connect to the LED from the PIC16F1826 circuit.... then I connect to the diode part of the cosmo1010 (this mean is flashing inside the cosmo1010? The cosmo1010 transitor part signal to the input of retriggerable monostable circuitry (or the missing pulse signal circuit).? Any special circuit you can suggest to me? Thank you very much.
     
  15. johnal2

    Thread Starter New Member

    Aug 11, 2014
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    Hi Mike
    The flashing rate and duration is about 2 per sec. Thank for the circuit and I will try it tonight. To Adamclark, I used cosmo1010 IC and connect to the LED directly... that mean it is flashing in the cosmo1010 directly and the signal output is also from the cosmo1010 transitor to the new circuit. Thanks
     
  16. MikeML

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    Check if the LED in the existing circuitry has its cathode tied to ground. If not, you may have to use an isolated supply to power the 555 circuit, or we could revamp the input circuit to the 2n3904.
     
  17. johnal2

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    Aug 11, 2014
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  18. johnal2

    Thread Starter New Member

    Aug 11, 2014
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    To MikeML
    Happy Labor's Day. Today, I just have a little time and made up the missing pulse detector (circuit # 2), that you suggested to me on August 14. Circuit # 1 is my PIC16F1826 with a piezo detector to generate pulse output of the LED. The voltage is 12VDC and the circuit #2 (LM555) pin # 2, 6 voltage is 8.07V. when I connected GND of the circuit # 1 that consisted of IC PIC16F1826 to the circuit # 2. The circuit # 1 LED is flashing like crazy with no signal input. Circuit # 2 relay never turn on with or without pulse input to the 1K resistor. If I connect circuit #2 pin #6 to pin # 7 then the relay is "ON" regardless of pulse input. Thank
    Kyle
     
  19. johnal2

    Thread Starter New Member

    Aug 11, 2014
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    Hi MikeML
    I took the 2n3904 out and replaced with a cosmo1010. It works exactly like I want. However, if I connected my two circuit GND together then the LED flash like crazy (circuit # 1(PIC16F1826) GND to circuit # 2 (your suggested missing pulse LM555 ) GND).
    Now, I am trying to see if your Missing pulse circuit LM555 pin#3 output or maybe pin #4 or pin # 7 could do (ON and OFF in the opposite way of pin # 3). Many thanks for your circuit.
    Kyle
     
  20. johnal2

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    Aug 11, 2014
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