Wifi isolation for pir sensor



  • Hello

    I read that it was necessary to put a ferrite bead around the cables, I try but it doesn’t work. You know how to do it and where on the cable ?

    Thank you :)



  • @vicdilou said in Wifi isolation for pir sensor:

    Hello

    I read that it was necessary to put a ferrite bead around the cables, I try but it doesn’t work. You know how to do it and where on the cable ?

    Thank you :)

    The ferrite bead is not “necessary” it was found to be a good workaround to the problem where the Pi and Pir Sensor don’t really get on if they are placed too closely…
    The ferrite bead location on usb cables and such, is always near the power end, so I would say to place it about 1/3 away from your Pi.

    I always wodered why longer cables are not used in this instace, to take the sensor as far from the Pi so it won’t cause interferrence.



  • @johnnyboy the sensor will be about sixty centimeters of raspberry



  • @vicdilou said in Wifi isolation for pir sensor:

    @johnnyboy the sensor will be about sixty centimeters of raspberry

    60cm… Wow, that is a good distance away from the Pi… but it still won’t work? Strange :-(
    I’ve not got round to hooking mines up yet, so can’t tell you what other troubleshooting steps to take here, but going by the 60cm distance, I would not expect any interference.

    As an aside, did you make up that length of cables yourself? Ive not seen any commercially made ones that length.

    As for your initial question about the ferrite bead… use a Hacksaw and cut lengthways till your half way through (or all the way - it doesn’t matter)… prise it open, and place cable inside and close up the ferrite bead, and use sticky tape to keep the bead clamped around the cables… Its what is inside the bead that does the work.
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  • @johnnyboy I used several cables

    I have to put all the cables in the ferrite bead ?



  • @vicdilou said in Wifi isolation for pir sensor:

    @johnnyboy I used several cables

    Several cables joined together? So about 3 each per strand to take you to 60cm? say, 9 cables in total to give you 3 X 60cm lengths?

    Yes you need to put the 3 cables into the bead.

    This may be where your fault lays if there is the slightest break in any of the connections?

    Im sure there will be a method to see if the sensor is being picked up on the MM, but I do not know this way :-(
    If you had a breadboard, I suppose you could test the connections there?



  • @johnnyboy There is no break in connection I think, I use this to test the sensor and it says always “Motion detected”.

    from gpiozero import MotionSensor
    import time
    
    pir = MotionSensor(4)
    
    while True: #repeat this forever
        if pir.motion_detected: # if motion is detected print the message
            print("Motion detected!")
        if not pir.motion_detected: # if no motion is detected print the message
            print("No motion detected!")
        time.sleep(1)
    

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