Connect with us

vibration sensor magnetic

Discussion in 'Datasheets, Manuals and Component Identification' started by sherazi, Jun 20, 2011.

Scroll to continue with content
  1. sherazi

    sherazi

    91
    0
    Mar 8, 2010
    i want to implement a vibration sensor that has a amgnet attached ona spring and a coil that gets the magnetic flux change converted to current. and then the current is amplified and a relay is switched... but i cant find the coil and the magnet piar anywhere from internet... i dont know what is this components special name etc.. but i have some oics that i would share if some one knows the name or some supplier plz tell me its name or from where can i buy this, the blue one is a coil .
     

    Attached Files:

  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,411
    2,779
    Jan 21, 2010
    Waaaay too blurry to make anything out.

    I expect the yellow thing is a relay and the blue thing is a choke. There's a trimmer of some sort there. I've seen spring things like those that detect significant shocks over 2 axies, but I can't tell if that's what they are, or if my imagination is running away with itself.
     
  3. poor mystic

    poor mystic

    1,066
    31
    Apr 8, 2011
    What sort of vibration is it please? What frequency and amplitude is it?
     
  4. poor mystic

    poor mystic

    1,066
    31
    Apr 8, 2011
    do you reckon that's an acoustically active spring there? then all it needs is a microphone.
     
  5. davenn

    davenn Moderator

    13,645
    1,884
    Sep 5, 2009
    one wonders if people even review their pix before they post them

    try again sherazi, they are totally unreadable ;(


    cheers
    Dave
     
  6. sherazi

    sherazi

    91
    0
    Mar 8, 2010
    sorry for the bad quality of snaps, i will post new here
    this is for alarm systems, its used to check if someone try to hit the door or try to open it forcefully... the spring is the same as described by Steve

    the blue thing is a two terminal package for a coil, i had tried to tear open one and its just a coil wound on a plastic core. the concept is that the spring has a permanent magnet on it, when there are vibrations the spring makes the magnetic field to vibrate that induces some current in the coil, the signal is then amplified and through comparator fed to relay....
     
  7. sherazi

    sherazi

    91
    0
    Mar 8, 2010
    sorry once again for the older pics...

    this is marked L1 that means its an inductor, but i am just wondering if there is a pair for magnet value and the inductance value for optimum results, or is it just a separate inductor,

    how can i get optimum results?
     

    Attached Files:

  8. sherazi

    sherazi

    91
    0
    Mar 8, 2010
    can u plz explain this here ,i think this is the principle of doing it...
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,411
    2,779
    Jan 21, 2010
    OK, it almost makes sense now.

    I guess there's a magnet in the end of that spring thing?

    As the magnet vibrates a small current is induced in that inductor. That small current is amplified and possibly closes the relay.

    edit: ok, you know that much. I expect the inductor is a standard part. Just an inductor on the appropriate former. The magnet and spring thing is a custom piece of hardware I expect.
     
    Last edited: Jun 21, 2011
  10. sherazi

    sherazi

    91
    0
    Mar 8, 2010
    how should i choose the inductor? value etc
     
  11. poor mystic

    poor mystic

    1,066
    31
    Apr 8, 2011
    I was thinking that the magnet, wobbling around on the end of the spring, would induce a small current in the litz wire, which would be converted to a negative-going pulse in the collector of the darlington.
    The smoothed collector voltage (charge/discharge time constants can be jiggled using diodes) would be compared against a reference set with a potentiometer. The comparator would drive a MOSFET power switch.
     
  12. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,411
    2,779
    Jan 21, 2010
    Very hard to say. You'd have to consider the strength of the magnet, their relative spacing, the sensitivity required, and the amount of amplification available.

    I think it would be a trial and error thing.

    You could remove that one and measure it though (presuming it doesn't have markings).

    If I were going to experiment, I might start with a 1000uH choke though. I can't imagine it's too critical, there are so many other variables that can be used to adjust it's behaviour.
     
  13. duke37

    duke37

    5,364
    769
    Jan 9, 2011
    You could try a diddy earphone with a weight glued to the diaphram. This will give you a coil and magnet set up optimally. The output impedance will be low and could go into the base of an amplifying transistor.
     
  14. poor mystic

    poor mystic

    1,066
    31
    Apr 8, 2011
    ... something like this, maybe?

    PS well no , actually
    No matter how I try and bias the transistor (not shown) I can't get a single stage amplifier to feed a charge pump. Not when the starting signal is so small.
     

    Attached Files:

    Last edited: Jun 21, 2011
  15. poor mystic

    poor mystic

    1,066
    31
    Apr 8, 2011
    It just occured to me that a comparator could be biased just "off" by resistive ladders, and the pick-up coil could sit across the ladders.
    I also had the idea that a moving-coil magnetic pickup would be the ideal transducer.
     
  16. sherazi

    sherazi

    91
    0
    Mar 8, 2010
    can u describe that in a schematic?
     
  17. poor mystic

    poor mystic

    1,066
    31
    Apr 8, 2011
    Here's the comparator idea. Please take no notice of 1H - a pickup coil is less inductive than that. This cct needs low-pass filtering too, which I have not drawn.
     

    Attached Files:

    Last edited: Jun 25, 2011
  18. sherazi

    sherazi

    91
    0
    Mar 8, 2010
    I am going to try this circuit, but today i dont have the components, so i would be waiting for them, in the mean time i wished to share this here, and get some opinions, corrections or suggestions.

    the coil gets induced current by the change in flux due to the vibrating magnet,the signal is amplified by the lm358 and a relay and LED is switched... if some one can explain it in detail it would be really nice...
     

    Attached Files:

  19. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,411
    2,779
    Jan 21, 2010
    The key piece is D2/R8/C3.

    The signal is rectified by the diode. This places a voltage across the capacitor which is allowed to leak away slowly. This voltage is used to signal that a relay should be closed.
     
  20. sherazi

    sherazi

    91
    0
    Mar 8, 2010
    thanx, and can u explain the circuit with the coil, why we need caapcitor and coil in series
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-