water flow sensor using ua741

Discussion in 'General Electronics Chat' started by maeanne21, Jan 30, 2013.

  1. maeanne21

    Thread Starter New Member

    Jan 30, 2013
    9
    0
    hello! can somebody help me on constructing a water flow sensor circuit diagram using ua741 IC ? please help me. . anybody. .
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,056
    3,245
    A 741 can amplify but it can't detect water flow.

    What water flow sensor are you using?
     
    Brownout and maeanne21 like this.
  3. maeanne21

    Thread Starter New Member

    Jan 30, 2013
    9
    0
    im trying to run my water flow circuit diagram at circuitlogixpro, but it doesn't work, can somebody gave an alternative water flow circuit diagram using ua741? thanks.



    mae anne
     
  4. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    Can you explain what the sensor is, as well as provide a schematic of the circuit?
     
    maeanne21 likes this.
  5. maeanne21

    Thread Starter New Member

    Jan 30, 2013
    9
    0
    good day sir,the sensor were using is a piezoelectric transducer. we choose ua741 opamps because its an all purpose op amp at the same time it is the alternative for our first choice lm613 which is not available here in our place. thanks and God Bless.
     
  6. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    If you are attempting to determine water flow using ultrasonic transducers, the LM741 will NOT work. You will need a newer, low noise op amp.

    Please provide a schematic (Attach to post using paperclip. Format preferred is .PNG, though .gif and .jpg are OK as well if legible).
     
    maeanne21 likes this.
  7. maeanne21

    Thread Starter New Member

    Jan 30, 2013
    9
    0
    heres our circuit diagram sir for water flow sensor.thanks.
     
  8. maeanne21

    Thread Starter New Member

    Jan 30, 2013
    9
    0
    by the way ,our flow sensor is a peizoelectric transducer. can somebody help me for this circuit diagram? thanks.
     
  9. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    One transducer, driven with a DC voltage?

    The schematic is illegible. However, the uA741 has noise issues, and very limited bandwidth. Since you are using a transducer, you'll be working with frequencies the 741 cannot process.

    What other op amps do you have access to?

    The schematic is FAR from complete for what I am GUESSING your project is. Is this what you are trying to achieve?

    The 741 doesn't provide gain past 20kHz or so, in addition to the noise it adds.

    Here is the 741 output swing vs. frequency, notice the sharp drop past 10kHz (With a ±15V Supply it can only output a 12V swing, which gets worse as frequency increases):
    [​IMG]

    For comparison, A TL071 op amp, one of MANY other options (at same or lower price) than a 741, Notice the flat response well past the frequencies you'll be using:

    [​IMG]

    In short, to even start, you'll need

    • An Oscillator Circuit
    • A better Op Amp
    • Processing beyond the Op Amp
     
    maeanne21 likes this.
  10. maeanne21

    Thread Starter New Member

    Jan 30, 2013
    9
    0
    good day sir, thank you so much for your reply, we would like to ask if this TL071 op amp is a good op amp for water flow sensor? we are trying to detect the flow rate of water flowing( creek water).


    thank you so much sir..
     
  11. maeanne21

    Thread Starter New Member

    Jan 30, 2013
    9
    0
    good day sir, we are using a piezoelectric transducer for our water flow sensor. are we going to use tl071 op amps? or do you have any suggested op amps sir?

    thank you.
     
  12. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    I don't know what frequency you plan to use. Free air ultrasonic transducers operate around 40kHz, I don't know what frequency your transducer will be using.

    Do you have a block diagram or full schematic of how the system will operate? Flow sensing via ultrasonic is not a simple and easy task, a fast microcontroller is usually involved to interpret timing and display the output. I've honestly never seen a flow meter measure a non-confined flow, such as a stream. Only flow meters that connect to pipes that have water moving in them.
     
Loading...