# circular waveform using oscilloscope

Discussion in 'Homework Help' started by Rubs, Jun 27, 2011.

1. ### Rubs Thread Starter New Member

Jun 20, 2011
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how can i generate a circular waveform on an oscilloscope using function generator?

2. ### beenthere Retired Moderator

Apr 20, 2004
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Rubs likes this.

Jun 20, 2011
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4. ### Georacer Moderator

Nov 25, 2009
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There is no rectangular shape possible with this method. Lissajous curves come in the pattern shown in the red images in the Wiki link beenthere gave you.

5. ### Rubs Thread Starter New Member

Jun 20, 2011
16
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u mean we cannot generate a parallelogram using a function generator?

6. ### Georacer Moderator

Nov 25, 2009
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A function generator can only give you, as it says, a function. That means that if you draw a vertical line anywhere in the graph, it will intercept the signal only at one point. A parallelogram will be intercepted at two and thus isn't a valid time signal.

Do you by any chance mean a square wave?
http://en.wikipedia.org/wiki/Square_wave

7. ### Rubs Thread Starter New Member

Jun 20, 2011
16
0
yea i knw dat...even a circle is generated using two sine signals with a phase difference of 90 degree. so my question remains..how to generate a parallelogram?

Apr 5, 2008
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Hello,

Try to reconstruct the signals needed to make a paralleogram.
It will be something like a trapezium like signal on one side.

Bertus

9. ### ErnieM AAC Fanatic!

Apr 24, 2011
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To draw a straight line one side is held steady while the other ramps from one voltage to the other. To draw a diagonal line both sides would ramp from one voltage to the other.

This was once done on computers and was called a "vector display." However, that term has been usurped by the latter day PC crowd so a search will generate many false hits.

To do it properly you might try a pair (or 2 channel?) of arbitrary waveform generators, but that widget ain't cheap. To do it on the cheap you might want to try the sound card audio output on your PC: left & right become X & Y.

10. ### BillB3857 Senior Member

Feb 28, 2009
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Two triangle waves, 90 degrees out of phase tied to X and Y inputs on scope?

11. ### Georacer Moderator

Nov 25, 2009
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If X and Y are the two input signals, starting from 0, a square with a side of 1 could be drawn parametrically like this:

For t=(0,t1) X=0, Y=t/t1
For t=(t1,t2) X=(t2-t)/(t2-t1), Y=1
and so on...

That requires an arbitrary signal generator as Ernie said. Why don't you try it in a simulation software for starters?

Is that clear?

12. ### #12 Expert

Nov 30, 2010
16,031
6,540
I can just about see it with a triangle wave on the x input and a clipped triangle wave on the y input. A resistor to a pair of diodes to do the clipping for the y input.

Function generators don't provide clipped triangles. That forces the use of hardware to do it this way.