Completely Analog Ultrasonic Range Finder

Discussion in 'The Projects Forum' started by simply_me, May 6, 2010.

  1. simply_me

    Thread Starter Member

    May 6, 2010
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    0
    Hello,



    I'm trying to design an ultrasonic range finder using only analog components and that its range will exceed 2m. So far I've designed the Wien Bridge (40Khz), bandpass amplifier, and a sinusoidal to rectangular wave form converter. So what I have in mind is-- The oscillator generates a sinusoidal wave sends it to the bandpass amplifier and from there one input goes to the transmitter and the other goes to the sine to rectangle converter. Now, I'll use a time delay circuit to pulse the rectangular wave (with a delay of about 12ms-- distance/speed of sound--4m/(343m/s), from there i thought to use a comparator to turn the receiver on to wait for a reading. Does anyone know how I can turn the receiver on for just 12ms? On the other side I'll have the sinusoidal wave pulsed all the time. At the receiver end, once it's turned on I want to put a threshold op-amp (not sure on how to implement it, but I'll do some research) and from there to amplifier. Once I have the output voltage readings, I'll use something similar to a voltmeter to read the distance (i.e. just a needle w/distance marks after doing manual measurements). Does that sound a reasonable design? Does anyone can point me to how to go about turning the receiver on/off every ~12ms?
    Someone suggested to me to use frequency sweep and frequency to voltage converter instead of the above approach, but the only problem is that I don't know how to do a frequency sweep in analog or find any example circuit.
    I'll be happy to hear any input/different approach you might have.



    Thank you,



    A
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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