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SIGNALS RELECTED BY WATER

Discussion in 'General Electronics Discussion' started by joy, Nov 12, 2013.

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  1. joy

    joy

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    Nov 12, 2013
    im working on a project where i need a sensor to
    1)send a signal to the water surface,get reflected
    2)calculate the reception time at every instant

    can u plz suggest the best sensor to do tht
     
  2. GreenGiant

    GreenGiant

    842
    6
    Feb 9, 2012
    your best bet would probably be an ultrasonic range sensor.

    Though the absolute BEST option would be a float sensor with an encoder, something that floats on top of the water that senses how far it has travelled with a guide cable.
     
  3. joy

    joy

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    Nov 12, 2013
    but in my project "the sensor and the time calculation circuit " should be away from the water surface......so i think that float sensor will not work
     
  4. jpanhalt

    jpanhalt

    426
    4
    Nov 12, 2013
    I have used a TOF laser range finder (like the Stanley FatMax) to measure water depth. Something along that line might work for what you want to do, but your description of the geometry involved is quite vague. In particular, are you talking about reflection back from the water or forward, glancing reflection? What is your end goal?

    John
     
  5. GreenGiant

    GreenGiant

    842
    6
    Feb 9, 2012
    Is this for school?

    I was pointing out that the most reliable way would be to use a float with an encoder of some sort, but I would still recommend an ultrasonic as the best one for a distance measure, a laser sensor might work but I dont think it would be super reliable, especially if there is turbulance on top of the water.

    The Ultrasonic will only work straight on, well mostly straight on, and it will only work so far.

    We need more information, how far is it going to fluctuate?
    How big of a distance are you talking about?
     
  6. joy

    joy

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    Nov 12, 2013
    k...i ll give a clear picture...im designing a small CAP for a water TAP...
    REQUIREMENT: the device should have a transmitter and a receiver inorder to continously transmit and receive the REFLECTED radiation...

    the time taken for reflection will start remaining same once the beaker/utensil is filled.....
    this should trigger the CAP to close.......its a small approach to save wastage of water due to overflow
     
  7. joy

    joy

    5
    0
    Nov 12, 2013
    k...i ll give a clear picture...im designing a small CAP for a water TAP...
    REQUIREMENT: the device should have a transmitter and a receiver inorder to continously transmit and receive the REFLECTED radiation...

    the time taken for reflection will start remaining same once the beaker/utensil is filled.....
    this should trigger the CAP to close.......its a small approach to save wastage of water due to overflow
     
  8. jpanhalt

    jpanhalt

    426
    4
    Nov 12, 2013
    I am sorry, this sentence just doesn't make sense to me:
    The ellipsis at the end adds no useful information. It seems you are trying to determine the water level in a beaker so when that beaker gets full, the water flow can be turned off, and similarly, when the level reaches a pre-determined low mark, the water source can be turned on again.

    Why do you want to continuously transmit and receive the reflected "radiation?" To where are you transmitting the reflected radiation?

    Ultrasonic distance measuring has been suggested. That seems reasonable to me. But, you seem to have rejected it. The method I suggested will also work, if the container is reflective. BTW, in the method I used, the depth is determined from the reflection off the bottom of the container, not the top surface of the water.

    Can you post a sketch to help eliminate some of our confusion?

    John
     
  9. joy

    joy

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    0
    Nov 12, 2013
    continuously transmit and receive the reflected "radiation"- because my final goal is to turn off the tap when the water rise in the utensil stops.,inorder to do this i will have to monitor the distance between the mouth of the tap and the water surface.

    To where are you transmitting the reflected radiation?- im not transmitting the reflected radiation anywhere.im just trying to calculate the recption time for every second, the moment 2 concecutive samples gives the same reception time,i will have to turn off the tap

    and thanks for the UV distance measurement method . can u suggest me how to build the circuit? im kinda new to electronics but im good with my basics
     
  10. jpanhalt

    jpanhalt

    426
    4
    Nov 12, 2013
    Why not measure the distance between the water surface and the bottom of the container?

    The method I described is not based on UV. The laser beam is typically red light. Considering that the claimed accuracy is ±1 to 2 mm and the speed of light is 3X10^11 mm/sec (i.e., 1 mm ≈ 3 pS), you need some well-designed circuitry and a special laser to do that, I would buy a ready made unit and adapt it to my purpose. The unit I bought cost ca. $50 USD new. The time differences using ultrasounds would be orders of magnitude greater and easier to measure with home built equipment.

    You could also mount the beaker on a strain gauge and determine when the weight stops changing. Have you been told that you have to use reflected light?

    John
     
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