Discussion in 'The Projects Forum' started by Adolph012, Apr 28, 2015.

  1. Adolph012

    Thread Starter New Member

    Apr 15, 2015
    I am using a Common Emitter amplifier to receive the reflected ultrasonic from an object.I also have to Integrate the transmitter and receiver to make an ultra-sonic proximity detector that can detect the presence of an object from a distance of 50 cm. And finally I have to Indicate the detection of the object by an audible tone.

    I am using a 741 op amp and i need help with the design. any input will be highly appreciated.
  2. sirch2

    Well-Known Member

    Jan 21, 2013
    There are loads of ultrasonic distance circuits on the Web, try Google.
  3. Dodgydave

    Distinguished Member

    Jun 22, 2012
    dump the 741, and use a better op amp, can you post your circuit..
    Sensacell likes this.
  4. Reloadron

    Active Member

    Jan 15, 2015
    You do not mention what you already have? Given a choice, based on your post, I would find an ultrasonic sensor package like this one. Simply because it offers an analog output. I would run that analog output through an amplifier, the sensor outputs about 10 mV / Inch (2.54 cm). Give the amplifier a gain adjustment to allow calibration, you do not need much. Then pass the amplified DC level to a window comparator to detect an object in your 50 cm range. Using a window comparator will allow you to omit objects closer than and further than 50 cm with relatively good accuracy. There are, as mentioned, much better operational amplifiers available today that the 741. Maybe 40 years ago I would have used a 741 but not today. I kept this analog for simplicity, this can also be done using a micro-controller.

  5. AnalogKid

    Distinguished Member

    Aug 1, 2013
    Is this a school project, a work project for a product design, a home project, or what?

  6. Adolph012

    Thread Starter New Member

    Apr 15, 2015
    Okay... sorry guys my bad, what I am actually designing is an ultrasonic proximity detector. I am going to modify a CE circuit design that i previously did and use it as a receiver, and I also designed a 40KHz wien bridge oscillator at Output voltage of 2V(p-p) which I wish to use, obviously I will have to modify it also, and use it as transmitter.

    Its a school project. I will post the circuit later on because I am currently busy with the design part.