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Pulse Stretching

Discussion in 'Automotive Electronics' started by Freddy1333, Jul 28, 2015.

  1. crutschow

    crutschow Well-Known Member Most Helpful Member

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  2. Freddy1333

    Freddy1333 Member

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  3. Diver300

    Diver300 Well-Known Member

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    I don't think that one will do the pulse stretching. It seems to be a a delay timer, so that the relay will be energised 1 - 20 seconds after power is applied.

    The three-way connector is connected by fatter tracks to the relay only. Those are the Common, Normally Open and Normally Closed connections. The two-way connector is the power input.

    A pulse stretching device would need at least three input connections, for power, ground and the pulse input.
     
  4. dave

    Dave New Member

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  5. Freddy1333

    Freddy1333 Member

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    Thanks Diver. Well ,the other ones is obviously the same. What do I need to do the job?
     
  6. crutschow

    crutschow Well-Known Member Most Helpful Member

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    Besides the circuits we've already shown, you can search for a monostable circuit, for example this.
     
    Last edited: Aug 9, 2015
  7. atferrari

    atferrari Well-Known Member

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    As the TS/OP describes it, it does not seem that a stretched pulse would do it. It sounds that it should be a bistable, set by event A (igniton turning ON) and reset by event B (ECU).
     
  8. Freddy1333

    Freddy1333 Member

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    Crutsy, isn't that the same as I already put a link to?
     
  9. Freddy1333

    Freddy1333 Member

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    Thanks atferrari. what now??? :confused:
     
  10. Freddy1333

    Freddy1333 Member

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    Getting back to the LED, despite what I said in reply 14 and upon further playing with the system, I cannot get the LED to come on with the key. The unit had 2 faults held in the ABS ECU, one was low battery voltage and the other was ECU trouble - operation abnormal (from a wrecked donor bike). I cleared those faults as per the manual, checked that they were clear, as per the manual, turned off the key, unplugged the front sensor and turned the key on for a bit then off. I put the system back into fault code mode and it had the code 43 - front sensor shorted or open. The really odd thing is that the LED works the opposite way it's supposed to in 'fault code' mode ie, it's on when it should be off and vice versa. I confirmed this by comparing it with my series 1 1400GTR (the type of bike the unit is from) in fault code mode for the same fault - front sensor unplugged, cleared and rechecked both a couple of times. So I have come to the conclusion that the bike's ECU, which is connected to the ABS ECU via the dash/meter, controls the LED and makes it works as it should and that having the bike's ECU out of the circuit on the 1000GTR I'm fitting it to causes the LED to work in reverse - if you follow what I'm on about. Page 12-44 (shown on page 2 of this thread) shows when it should be on and off under which conditions. It's actually off when it should be on and on when it should be off, so instead of counting blinks, I count blanks and get the correct fault code. Follow? I tried wiring in a change-over relay to reverse the operation but the current draw thru the ABS ECU is too low to activate a relay.

    Any help on how to get it 'into reverse?'
     
  11. Tony Stewart

    Tony Stewart Well-Known Member Most Helpful Member

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    LED operation can be reversed between Active High or Active Low easily with Anode on the + side always and using low side drive on the upper LED or high side drive on the lower example.
    upload_2015-8-17_22-13-36.png
     
  12. Freddy1333

    Freddy1333 Member

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    Thanks Tony. Can you please walk me thru precisely what I need to do/get/fit to make this happen. Thanks
     
  13. Tony Stewart

    Tony Stewart Well-Known Member Most Helpful Member

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    I dont know where the LED is physically located or wired, but this involves changing two connections on the LED as shown. From one to the other.

    {Perhaps it is easier to add a 2nd LED and resistor to correspond with your active signal High or low.}

    LED mount or unmount and rewire is up to you.
    IF 5mm it looks like this.


    upload_2015-8-19_19-57-15.png
     
    Last edited: Aug 19, 2015
  14. Freddy1333

    Freddy1333 Member

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    It'sa 12V aftermarket LED that I have fitted. Do you mean to reverse the wires to it? If so I'be done that to no avail.
     
  15. Tony Stewart

    Tony Stewart Well-Known Member Most Helpful Member

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    No only one wire is reversed , the other changes power polarity + or gnd.

    In order to help you, I need to know which configuration matches your circuit.

    If the red lead is always on 12V change that to input or visa versa.
    If the black lead goes to input , change that to gnd or visa versa.
     
    Last edited: Aug 20, 2015
  16. Freddy1333

    Freddy1333 Member

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    Tony, allow me to back up a bit due to my ignorance. Your pic above shows another diode, right? What is the 470, a resistor? I do not have these items yet.

    The LED red wire is always +ve.

    Thanks for you help.
     
  17. Tony Stewart

    Tony Stewart Well-Known Member Most Helpful Member

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    LED's must all have some current limiting resistor.

    Yours must be built into the wiring, so ignore that.
     
  18. Freddy1333

    Freddy1333 Member

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    OK Tony. Can you walk me thru the connections I need to make please.
     
  19. Tony Stewart

    Tony Stewart Well-Known Member Most Helpful Member

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    read my previous post , it still applies. YOu havn't told me what polarity your signal is.
     
  20. Freddy1333

    Freddy1333 Member

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    Ignorance isn't bliss. The signal is -ve.
     
  21. Tony Stewart

    Tony Stewart Well-Known Member Most Helpful Member

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    We call that active low, or 0V in to enable LED when Anode or Red wire is connected to 12V.
    Dont you have a volt meter.

    If not, disconnect and ground input and LED should turn on.

    Then rewire as directed before
     

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