Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: yyy on September 25, 2009, 02:56:58 AM

Title: signal
Post by: yyy on September 25, 2009, 02:56:58 AM

How can I convert square signal to sin signal ?
Also I need that it will fit to wide frequency range
Why in resonance circuit the convert frequency is only for one specific frequency?

Title: Re: signal
Post by: billhowl on September 25, 2009, 03:21:55 AM

It can be done with two stages of integrators, the first one converts the square wave to a triangle wave, and the second stage converts the triangle wave to a sine wave. If the input frequency varies widely then the output amplitude will vary.
Here is a typical schematic, two identical stages are required

A Quick Sine Wave Generator
http://www.national.com/nationaledge/jun04/article.html (http://www.national.com/nationaledge/jun04/article.html)

Title: Re: signal
Post by: Soeren on September 25, 2009, 03:58:52 AM

Hi,

Quote from: yyy on September 25, 2009, 02:56:58 AM

How can I convert square signal to sin signal ?
Also I need that it will fit to wide frequency range

How wide?

Can be done in several ways - a PLL controlling a DDS Sine generator would be my choice.

Title: Re: signal
Post by: yyy on September 28, 2009, 07:15:41 AM

Thanks billhowl & soeren
Soeren, what do you main in PLL controlling ?
Can you explain it ?

Title: Re: signal
Post by: Soeren on September 28, 2009, 09:38:27 AM

Hi,

Quote from: yyy on September 28, 2009, 07:15:41 AM

Soeren, what do you main in PLL controlling ?
Can you explain it ?

PLL = Phase Locked Loop.
DDS = Direct Digital Synthesis

The PLL looks at both the output from the DDS and your square wave signal and "locks" the two together.
If the signal drifts/deviates, the PLL will correct it,
The output from a DDS can be anything you can imagine, sine, triangle, saw tooth or something entirely different, like the quack of a duck ;D

What's your purpose with the converted signal?