Keyless Entry - External Circuit to Repeat Pulses

Discussion in 'The Projects Forum' started by dirtyrobinson, Aug 23, 2018.

  1. dirtyrobinson

    Thread Starter New Member

    Aug 23, 2018
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    I have a very basic keyless entry module and it only sends one pulse to the door lock solenoid, the problem is the car being old requires 2 or 3 pulses to actually lock or unlock the door. It is a negative trigger system.

    Is there something I can add between the module and solenoid that will receive the initial pulse from the module and repeat that pulse 2-3 times?

    Thanks
     
  2. danadak

    Distinguished Member

    Mar 10, 2018
    3,078
    686
    Not easily. Either you hack the fob circuits, or build from the ground up a
    repeater that receives the fob signal, decodes it and re modulates another
    RF transmitter to output the other two+ pulses.

    Regards, Dana.
     
  3. crutschow

    Expert

    Mar 14, 2008
    22,244
    6,491
    Would just a longer pulse work to trigger the solenoid?
    That's easy to do.
    Sounds like the problem is a marginal signal pulse width.
     
    Kjeldgaard likes this.
  4. dirtyrobinson

    Thread Starter New Member

    Aug 23, 2018
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    Sorry I should specify, I'm not looking to repeat the RF signal to the module, I was thinking more of another relay that is triggered by the relay in the module.
     
  5. ericgibbs

    Moderator

    Jan 29, 2010
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    hi dr,
    I would say by reducing from 3 pulses to one will greatly reduce the door locks resistance to random RF noise, also the security aspect.
    E
     
  6. crutschow

    Expert

    Mar 14, 2008
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    The problem is that it shouldn't require three pulses.
    He wants it to operate with only one pulse from the remote.
    That's why I suggested increasing the pulse width.
     
  7. ericgibbs

    Moderator

    Jan 29, 2010
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    I have seen car remotes that require 3 pulses in quick succession in order to activate the lock.
    If only one or two pulses are received and the third pulse is delayed too long or is missing, the first pulse record is dumped, so no lock action.

    So I would ask the TS is the handfob/lock action of the required 3 presses, stated in the operating notes or is it something that has happened over time.??

    The other possible cause is the fob push button contacts maybe worn, so two or three presses are required.
    If that was the case, fixing the fob push button would be the simplest repair.
     
  8. ArakelTheDragon

    Well-Known Member

    Nov 18, 2016
    1,247
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    If you can put a PCB between the 1 pusle source and the door solenoid, then yes it is possible. You will need 1 MCU. The MCU receives the 1 signal and then sends 3 signals. A simple PIC10F200 will do. This means the voltages have to be 5VDC for the MCU, or you will need some converter before and after.
     
  9. crutschow

    Expert

    Mar 14, 2008
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    Yes, the TS should clarify this.

    He stated that
    so I assumed that it was a functional problem with the door lock, thus his request for the automatic generation of 3 pulses.
     
  10. ericgibbs

    Moderator

    Jan 29, 2010
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    I see also that he says, its an old car, so my best guess would be the hand fob switch is worn.
    If I am correct, changing the received pulse length would not fix the problem.
     
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