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i want to make a circuit to detect flow of water using ir leds — Parallax Forums

i want to make a circuit to detect flow of water using ir leds

munotvipulmunotvipul Posts: 1
in General Discussion
i want to make a circuit to detect flow of water using ir leds which will be later on connected to arduino so the thing is I'm from computer department and I don't have much knowledge about electronics. so the thing is which resistor should I use how to find the appropriate one for transmitting and receiving ir signals

Comments

  • Hal AlbachHal Albach Posts: 747
    This should provide some information;
    http://startrobotics.blogspot.com/2013/05/how-to-use-ir-led-and-photodiode-with-arduino.html

    How do you plan on using an ir LED and photodiode to detect the flow of water?
  • Heater.Heater. Posts: 21,230
    Your problem is not computer science or electronics.

    Your problem is physics. How are your going to detect water flow with IR?

    Whatever, you should be more specific, this water flow in a household water pipe or a river or what?
  • Duane DegnDuane Degn Posts: 10,588
    edited 2015-09-01 19:59
    Heater. wrote: »
    Your problem is not computer science or electronics.

    Your problem is physics. How are your going to detect water flow with IR?

    The requirement isn't "with IR" it's "using IR LEDs."

    This makes it easy. You drop the IR LEDs in the water and see how fast they move.

    I do wonder why the "IR LED" requirement is added.

    I suppose some sort of paddle wheel which interrupts an IR beam could be used. Of course a lot depends on the specifics of the application.

  • Heater.Heater. Posts: 21,230
    I like the idea. Drop the LEDs into the flow and see what happens :)

    The question as stated is so vague as to be unanswerable in a sensible way.
  • Dr_AculaDr_Acula Posts: 5,484
    heater said I like the idea. Drop the LEDs into the flow and see what happens

    Ah, you mean poohsticks?! https://en.wikipedia.org/wiki/Poohsticks

    Hmm, but do leds float? More experimentation needed...
  • Cluso99Cluso99 Posts: 18,069
    You could always tie the LEDs to a piece of string at a certain distance apart ;)

    After all, that was the basics (similar) to how ships speed (in knots) was determined.
  • Heater.Heater. Posts: 21,230
    Yes, poohsticks, blue LED illuminated poohsticks. For playing poohsticks at night measuring flow in the dark.
  • SeairthSeairth Posts: 2,474
    munotvipul wrote: »
    i want to make a circuit to detect flow of water using ir leds which will be later on connected to arduino so the thing is I'm from computer department and I don't have much knowledge about electronics. so the thing is which resistor should I use how to find the appropriate one for transmitting and receiving ir signals

    To clarify, are you trying to detect (A) when water is flowing or (B) how much water is flowing? If the answer is (A), then you are looking for an IR break beam circuit. There is plenty of online material about this. Since you specifically mentioned arduino, here's a link to get you started:

    https://learn.adafruit.com/ir-breakbeam-sensors
  • bill190bill190 Posts: 769
    FYI - Note that "water" can be quite different from different sources. It is not consistent in any way, shape, or form. There is "well water" and "water extracted from rivers" - that alone can make the water quite different. Then well water can have different mineral contents. Water from private wells might not be chlorinated, but city water usually is chlorinated. Fluoride may or may not be added to city water. River water can have different turbidity levels depending on the time of year (flooding can make muddy water, calmer times will have more clear water in rivers).

    To learn more about this, search google.com for the following words...

    water turbidity

    water mineral content

    water testing

    water chlorination

    water fluoridation

    water pH
  • Heater.Heater. Posts: 21,230
    The question as stated cannot be answered.

    Are we talking detecting a presence or absence of a flow of water, from a tap say?

    Are we talking measuring the speed of flow in a pipe? In a river?

    What actually has the resistor on an IR LED got to do with it?

  • kwinnkwinn Posts: 8,697
    Looks like the op may have left the building.
  • Beau SchwabeBeau Schwabe Posts: 6,547
    edited 2015-09-04 03:42
    Although the OP seems to have vanished, here is a thought that might work based on oxygen levels within the water. Using what amounts to the equivalent of an optical current mirror, you have one IR transmitter and two receivers. Using the reference IC below, I have personally built this circuit with discrete components with quite pleasing/surprising results, so something in Water might just work as nice. There will still need to be some sort of calibration in order for the readings to hold any weight, but the output should be proportional to the flow if one optical receiver (to the output) is in the flow, and the other is used for reference (current feedback). The key here is to take the input voltage and the output voltage from the reference circuit below and look at those two voltages deferentially as if they were originating from something akin to a strain gauge.

    Oxygenation/aeration could also be introduced from a control point within the flow as well with something like a venturi valve.

    Note: The IC below is just a reference to the circuit (See datasheet Figure A on page 11)
    http://www.digikey.com/product-detail/en/HCNR200-000E/516-1522-5-ND/696022
  • kwinnkwinn Posts: 8,697
    @Beau

    Can you elaborate a bit on that idea?
  • Beau SchwabeBeau Schwabe Posts: 6,547
    Attached is a theory ...
    pdf
    pdf
    IR Water Flow.pdf
    71K
  • kwinnkwinn Posts: 8,697
    Thanks for posting that. Interesting idea.
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