+ Post New Thread
Results 1 to 8 of 8
  1. #1
    Full Member level 3
    Points: 1,990, Level: 10
    Achievements:
    Created Album pictures 7 years registered
    pradeep_k_b's Avatar
    Join Date
    Dec 2011
    Location
    Nilambur, India
    Posts
    154
    Helped
    0 / 0
    Points
    1,990
    Level
    10

    What is inside a car shock/impact sensor?

    Hi ,

    I was trying to make a shock sensor.My idea was use a small condenser mic and detect the vibrations,and of course it works.But when I need to cover a large area for example 1mx1m area its difficult .Then I searched for the shock/impact sensors that used in old cars(I am not sure this is the same in new cars as well,but in new cars there are using many other sensors I think) .And I got a couple of product details and also some installation videos etc.But I couldn't find out how its working.Its just a box and it can detect the hit on the car

    This is one of the product https://www.amazon.com/Directed-Elec...993b086dedec9d

    And its an installation video https://www.youtube.com/watch?v=ri03oBDwpFE

    Anyone know what is inside that box? is it just a piezo sensor or a mercury tilt switch? then how it detecting any hit on the car using a single sensor?

    Looking forward to your feedbacks

    Thanks,
    Pradeep
    ".......One man's magic is another man's engineering. Supernatural is a null word......"

    •   AltAdvertisment

        
       

  2. #2
    Advanced Member level 5
    Points: 22,400, Level: 36
    barry's Avatar
    Join Date
    Mar 2005
    Location
    California, USA
    Posts
    4,284
    Helped
    949 / 949
    Points
    22,400
    Level
    36

    Re: What is inside a car shock/impact sensor?

    It says right there: "Uses patented electromagnetic technology".

    It DOES NOT say it uses a piezo; it DOES NOT say it uses a mercury tilt switch.

    Probably uses something like a ferrite rod that flops around inside a coil. But why do you care? If you really want to know, it looks easy enough to open.



    •   AltAdvertisment

        
       

  3. #3
    Super Moderator
    Points: 29,773, Level: 42
    ads-ee's Avatar
    Join Date
    Sep 2013
    Location
    USA
    Posts
    6,857
    Helped
    1635 / 1635
    Points
    29,773
    Level
    42

    Re: What is inside a car shock/impact sensor?

    From what I read about car systems, they use accelerometers to detect things like crashes for deploying the airbags and such. Old style car alarms used to use shock sensors (to detect things like windows being broken) can't tell you how many times back in the day that somebody on a Harley would rev their engine in a parking lot to set off all the shock based sensors of everybody who had a car alarm. Pre airbags I don't recall any kind of shock/accelerometers (other than possibly an engine knock sensor) used in cars, at least none were in any of the old shop manuals I had for cars I owned back then.



    •   AltAdvertisment

        
       

  4. #4
    Full Member level 3
    Points: 1,990, Level: 10
    Achievements:
    Created Album pictures 7 years registered
    pradeep_k_b's Avatar
    Join Date
    Dec 2011
    Location
    Nilambur, India
    Posts
    154
    Helped
    0 / 0
    Points
    1,990
    Level
    10

    Re: What is inside a car shock/impact sensor?

    Okay.Thank you very much for your comments

    But I am still curious about how they are achieving this by just connecting a small box under the dash board.I couldn't find any sensing element and all they are connecting a box only.If if detect the vibration ,the received vibration level will be different,right?.For example if someone hit on the back of the car there will be only a small vibration on the from dashboard
    ".......One man's magic is another man's engineering. Supernatural is a null word......"



  5. #5
    Super Moderator
    Points: 250,728, Level: 100
    Awards:
    1st Helpful Member

    Join Date
    Jan 2008
    Location
    Bochum, Germany
    Posts
    43,650
    Helped
    13275 / 13275
    Points
    250,728
    Level
    100

    Re: What is inside a car shock/impact sensor?

    I think you have difficulties to understand elementary law of mechanics. A car is a more or less rigid structure. If it's massively bumped, the acceleration can be sensed at any part of the chassis.



  6. #6
    Advanced Member level 4
    Points: 7,899, Level: 21
    Achievements:
    7 years registered Created Blog entry
    dpaul's Avatar
    Join Date
    Jan 2008
    Location
    Germay
    Posts
    1,174
    Helped
    254 / 254
    Points
    7,899
    Level
    21
    Blog Entries
    1

    Re: What is inside a car shock/impact sensor?

    I think there are more sensors rather than "just 1 box" in modern cars.

    But when I need to cover a large area for example 1mx1m area its difficult .
    You are just trying to build a prototype or proof-of-concept right?
    Why don't you try using 3 sensors placed 30cm apart, which each of them having the ability to trigger the main ckt when vibration is sensed.
    FPGA enthusiast!



    •   AltAdvertisment

        
       

  7. #7
    Full Member level 3
    Points: 1,990, Level: 10
    Achievements:
    Created Album pictures 7 years registered
    pradeep_k_b's Avatar
    Join Date
    Dec 2011
    Location
    Nilambur, India
    Posts
    154
    Helped
    0 / 0
    Points
    1,990
    Level
    10

    Re: What is inside a car shock/impact sensor?

    Quote Originally Posted by FvM View Post
    I think you have difficulties to understand elementary law of mechanics. A car is a more or less rigid structure. If it's massively bumped, the acceleration can be sensed at any part of the chassis.
    You are correct..Thank you

    - - - Updated - - -

    Quote Originally Posted by dpaul View Post
    I think there are more sensors rather than "just 1 box" in modern cars.


    You are just trying to build a prototype or proof-of-concept right?
    Why don't you try using 3 sensors placed 30cm apart, which each of them having the ability to trigger the main ckt when vibration is sensed.
    May be that will work if I try to do that.But in end product I need to cover 1m with one sensor
    ".......One man's magic is another man's engineering. Supernatural is a null word......"



  8. #8
    Advanced Member level 5
    Points: 22,400, Level: 36
    barry's Avatar
    Join Date
    Mar 2005
    Location
    California, USA
    Posts
    4,284
    Helped
    949 / 949
    Points
    22,400
    Level
    36

    Re: What is inside a car shock/impact sensor?

    Quote Originally Posted by pradeep_k_b View Post
    May be that will work if I try to do that.But in end product I need to cover 1m with one sensor
    You don't say what you're trying to sense, or why. If it's a rigid system, then you should be able to detect shock with a single sensor; if it's less than rigid, then you'll have problems (try pushing a rope). You don't say if you're just looking for the occurrence of ANY shock, or if you need more information from your measurement.



--[[ ]]--