how can i generate a circular waveform on an oscilloscope using function generator?

 

You probably want to generate a waveform that shows a circle on your oscilloscope - http://en.wikipedia.org/wiki/Lissajous_curve

 

You probably want to generate a waveform that shows a circle on your oscilloscope - http://en.wikipedia.org/wiki/Lissajous_curve

what should i do to get a parallelogram shape?

 

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.

 

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.

u mean we cannot generate a parallelogram using a function generator?

 

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

 

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

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?

 

Hello,

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

Bertus

 

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.

 

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

 

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?

 

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.

 

If you use the X and Y inputs of the scope (e.g., for Lissajous figures) and the Z input, then you can draw anything that you can draw on a piece of paper with a pen. I haven't seen a Z input on a scope in a couple of decades though... Theoretically, you can also do it without the Z input; it's just harder.