oscillator - toneburst

Discussion in 'The Projects Forum' started by krgoutham, Jul 20, 2006.

  1. krgoutham

    Thread Starter Member

    Dec 8, 2004
    22
    0
    hello

    i am working on a couple of projects simultaneously, and so you might see new threads under my name. I was trying to get a 5 cycle sinusoidal tone burst from an oscillator. Getting an oscillator is not a big deal but i dont know how to get exactly a 5 cycle toneburst. i am talking about frequencies on the order of a 1MHz. I did find a product from Analog Devices that actually can control the output of the oscillator using a D/A converter. But i want to keep everything analog and do not want to go into digital mode.

    any suggestions please.

    Thanks
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Hi,One way to do that is to use a four quadrant multiplier. You should be able to apply a signal to one set of inputs that will gate five cycles of your oscillator. It's been a while, so I don't have any particular device in mind. Another way might be to use a small power fet, like a 2N7000. Arrange the circuit so the signal passes through a resistor that will safely limit current. Use the fet to short the signal to ground after the resistor. Turn the fet off for a period that will pass five cycles.You might also be able to use analog switches, but they might not be fast enough.
     
  3. ttennis

    New Member

    Aug 16, 2006
    3
    0
    I know that you don't want to go digital, but it might be your best solution.

    Here is a simple way: Connect the 1 mhz to the clock input of a five stage D FF that has Q output 1 tied to Data in 2, Q out 2 to Data in 3 etc. Connect signal diode anodes to each Q out and then tie all the cathodes together. Your output for the five bursts will be at the cathodes' tie point. Of course, all your clock inputs are tied together.

    You can reshape this output with coils and caps to get a sine wave if desired.

    Reset all FFs before passing the next burst.
     
  4. krgoutham

    Thread Starter Member

    Dec 8, 2004
    22
    0
    Mr.TTennis

    Thanks for your reply. I have to go through your words a bit more carefully and understand it thoroughly before i can come to some conclusion. I shall put a few questions to you anyway on that issue sometime down the line.

    However i have another question and may be yourself or some other person in the group can suggest something. I managed to get an oscillator that produces a square wave (0 to +3volts). My sole purpose is to drive a piezoelectric sensor. But since my project requires driving the piezoelectric sensor at +/- volts. how would i do it. is there any other efficient way of converting the (0 to +3 volts ) output of hte oscillator into a +/- volts to supply my piezoelectric device.

    Thanks
     
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