Viewing 8 posts - 1 through 8 (of 19 total)
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  • #3659
    AvatarLuciano
    Participant

    Someone knows this sensor?
    I'm trying and I need its features
    I wrote to the seller and sent me a link but with very little information, only explanation for Arduino
    I need the datasheet but not “exists” I do not find anywhere
    Give me some good news
    Thanks Luciano

    #3665
    Avatartheremino
    Keymaster

    Plug it to GND and + 5V and consumes Master 40 mA, until everything is easy.
    Then there is the problem that its output goes from 2.5 It was the 4.3 volts while the ADC to read our 0 a 3.3 volt.

    So I would recommend you connect a red LED (which loses about two volts and has a fall fairly stable voltage with temperature) in series with the output and then a resistor 10 K to ground. The signal after the LED should go from about 0.5 He was in circa 2.5 volt, and then in the right range for our ADC.

    The signal SIGNAL connect it to the same Pin from which also fetch the 5V and the ground GND.
    You have to use one of Pins 1 a 6 which they are analog and can be configured as ADCs.

    And finally we set the Pin as Adc16 and controls with the HAL oscilloscope, and with maximum transparency and with maximum turbidity, the values ​​are in the range of 0 a 1000. Or rather no less than 200 and not more than 800, so do not get too close to the extremes.

    —–

    Here is the graph of the output voltage
    https://www.dfrobot.com/wiki/index.php/File:Relationship_diagram.jpg

    And here's the scheme
    https://github.com/Arduinolibrary/DFRobot_Turbidity_sensor/raw/master/SEN0189%20Turbidity%20sensor(V1.0)%20schematic.pdf

    #3668
    AvatarLuciano
    Participant

    Thanks for the answer but all this I was already aware
    For the sensor output to be connected to the master had solved with two resistors 22K and 12K
    The problem was the graphic, the Y-axis value indicates that? because calculating the value from the formula shown on the same, but what do I get?
    Luciano Greetings

    #3670
    Avatartheremino
    Keymaster

    With a divider still collapse the range that is already scarce. So exploiting an even smaller part of the ADC scale and decrease the resolution.
    However, it probably will be fine the same.

    To know what the values ​​mean just that:
    1) Do not put anything in between and read the number sull'HAL
    2) Put a black card and read the number sull'HAL

    The two readings are equivalent to zero turbidity and turbidity 100%.
    All intermediate values ​​will give an intermediate between turbidity 0% e 100%
    A linear proportion and you have the required result.

    #3727
    AvatarLuciano
    Participant

    I'm trying a new type of adapter for this sensor
    I want to amplify the weak signal coming out, because a change of 1000 NTU have a change 300 mV
    This signal would have about 0,3 mV x 1 NTU and it would be difficult to assess the changes when the value of drinking water and’ circa 5 NTU
    However, something I'm doing, to make him the new adapter scheme I opened the sensor to understand its circuit and I noticed that and’ different from that published, both as a pin that circuit, in fact, the pin 1-2-3-4 they do not exist
    I send you the actual schemereal scheme

    #3729
    Avatartheremino
    Keymaster

    For greater precision, you should use the form Adc24

    Or, to spend less, You may amplify the signal with an operational.
    But in this case you would have many more problems, less stability and less precision.
    And you should also adjust the minimum and maximum range of your interest with two trimmer in order to exploit the full dynamic of the ADC Master.

    #3770
    AvatarLuciano
    Participant

    I modified the sensor to obtain a signal that increases the turbidity increases if the adapter and replaced with a new circuit
    The input diode serves only to limit the signal so that I can increase the gain
    To power the’ LM358 a 12v. I have taken the 25v. from the circuit that I use for the control of conductivity
    This new evidence from the first circuit and’ more regular and repetitive, ie if a ripetto also measures the aftermath shows me the usual value
    The problem now’ calibration in NTU, the 0 I think calibrated using distilled water while the max example 100 NTU with 750mg of “RESIDUAL” What could I use?
    Thank you
    New adapter

    #3772
    Avatartheremino
    Keymaster

    This circuit amplifies the part that interests you and then the measurement is more stable and less affected by noise.
    It remains however the LEDs, like all LED, changes of brightness with the temperature, and then gradually reduces its light in the first minutes of ignition.

    For the 100 NTU can not tell you, I recommend to search the internet What is usually for these calibrations.

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