need help??!!

[mohaisen]

hey guys ... first of all this is my first post here..and i just want 2 say u r doin' great...

i need a small help ... i have a schematics that gererate a sawtooth and a square wave ..i want 2 modify that design so i have gererate a sin wave also ..thnx

i dont mind if u provide another design

 

[ericgibbs]

hi,
To get a decent sinewave from your circuit is not easy.

I would suggest that the 'front end' is a sinewave osc, which is then squared up using a compartor. This will give a 'square' wave that can drive the integrator to provide a sawtooth.

Does this help?.

Get this application note #31, lotsa examples.
**broken link removed**

 

[jumides]

few advice

hi mohaisen,
I'm also a new member her, just an advice for you not use "2" as replacement to "to" , let say " 2V 2 5V " is different from "2v to 5v". As respect to other member please Don't use "SMS text" type messages. Welcome to forum!!

 

[audioguru]

A pure sine-wave has no harmonics.
A pulse-wave and sawtooth-wave have both even and odd harmonics.
A square-wave and a triangle-wave have only odd harmonics.

A lowpass filter can reduce harmonics. The second harmonic is at a frequency that is close to the fundamental frequency so it is very difficult to reduce without also reducing the fundamental frequency. Therefore a square-wave or triangle-wave are the easiest to filter into a sine-wave.

i show your circuit modified to produce a triangle-wave and square-wave. The triangle-wave is filtered with a 2nd-order Butterworth lowpass filter circuit. The output sine-wave still has some harmonics, a 4th-order Butterworth filter circuit or switched-capacitor Butterworth lowpass filter IC will reduce the harmonics much more.