water flow sensor using ua741

Thread Starter

maeanne21

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

Thread Starter

maeanne21

Joined Jan 30, 2013
9
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
 

Thread Starter

maeanne21

Joined Jan 30, 2013
9
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.
 

thatoneguy

Joined Feb 19, 2009
6,359
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).
 

thatoneguy

Joined Feb 19, 2009
6,359
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):


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:



In short, to even start, you'll need

  • An Oscillator Circuit
  • A better Op Amp
  • Processing beyond the Op Amp
 

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Thread Starter

maeanne21

Joined Jan 30, 2013
9
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..
 

Thread Starter

maeanne21

Joined Jan 30, 2013
9
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.
 

thatoneguy

Joined Feb 19, 2009
6,359
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.
 
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