Help with ultrasonic sensors!

[ro5man]

Hey all,

First of all,I a total noob with sensors so I need a little help.

I need help with my ultrasonic receiver circuit,I got the transmitter circuit working (40kHz etc).I want the output to be based on the intensity of the received signal so that I can measure the voltage but I keep getting an output based on the frequency of the received signal.What kind of circuit can you guys recommend me so that I get a voltage output rather than a frequency output?

Many thanks to those who reply!

 

[ericgibbs]

Hey all,

First of all,I a total noob with sensors so I need a little help.

I need help with my ultrasonic receiver circuit,I got the transmitter circuit working (40kHz etc).I want the output to be based on the intensity of the received signal so that I can measure the voltage but I keep getting an output based on the frequency of the received signal.What kind of circuit can you guys recommend me so that I get a voltage output rather than a frequency output?

Many thanks to those who reply!

hi,
Can you post your receiver circuit.?

 

[dougy83]

For a voltage output relating to the intensity received, try connecting the receiver to an amplifier (must be capable of passing the 40kHz) followed by a peak-detector.

 

[ro5man]

Peak Detector,got it.Many thanks!

 

[tw0081]

Hi there, I am also building a transmitting circuit. Would it be possible for u to post a circuit diagram? Thanks

 

[RichTheDude]

As dougy said, create a non inverting amplifier with an OP-AMP (you may need 2 stages with something like a TL082 due to the gain bandwidth product), make sure you have an offset null on the input as well.

I would not even consider something like a 741, the GBP and slew rate make it horrible for 40 kHz amplification - in fact with enough gain you will end up with triangular waveforms...

Then just have a peak detector on the output (diode, cap and parallel resistor if the load is not sufficient to discharge rapidly enough).

(The only place I think a 741s should reside is in history books and teaching students the basics of op amps, I would never consider using one...).