Function Generator Sweeps

[walters]

Why does function generators have a Sweeping parameters?

What are the sweeping parameters used for?

What are some sweeping patterns? Linear, Log , Exp. what other ones?

How do i turn a Linear sweep circuit into a Log sweep circuit?
what would be the difference?

Thanks for the help and information on this

 

[panic mode]

let's say you want to test and/or adjust an amplifier or filter.
you could bring signal from function generator to input, connect some sort of device to measure output (oscilloscope, rf probe or whatever) on the output and test the stage. now you could do this by hand (set one frequency and measure output, set another slightly higher frequency and measure etc.) until you are finished. then you make small adjustment and repeat the whole thing from beginning. as you can see this could take a long time. so wouldn't it be nice to have some sort of automatic system that changes frequency over and over in range?

 

[walters]

Thanks for the information

frequency and measure output

When the generator is sweeping the frequency what would i be measuring? the voltage of the eq stage?

How would i test the frequency respones of a Filter stage or circuit with a sweep function generator?

 

[Russlk]

The log sweep produces a log display of frequency but the voltage sweep that drives the modulator is not logrithmic. You need a shaper circuit to convert the linear sweep to logrithmic. The attached plot is an example.

 

[walters]

Thanks for the information

So its a Frequency sweep VS voltage sweep

You need a shaper circuit to convert the linear sweep to logrithmic

What kind of shaper circuit ? where can i find these shaper circuits?

They are AC shaper circuits or DC shaper circuits?

 

[Russlk]

You can make a piece-wise linear DC shaper with diodes. The basic idea is shown below. I used to have a program that would calculate the values for an arbitrary curve but it is lost in antiquity. Ratz! I got the diodes backward, turn them around.