hi;

i need a special waveform.it actually consists of the sum of a half wave rectified sine and a half wave rectified triangle.upto know is a pienut.

however if you want to have steady output on the cro screen,this way doesn't work. due to two different signal sources there exists phase shift so you can not get a stationary signal on the cro screen.

so i have to somehow obtain teh triangle signal from the sine input.

if you have any comments, i will be very glad.

thanks

 

Hi,

Think about using a waveform generator ic like the ICL8038. It will go up to at least 100 kHz, and has sine, triangle and square outputs in perfect phase allignment.

If this sounds like the thing to use, check the VCO topic in the projects forum for a circuit to use.

 

thanks for your help;

your advice is a good solution but does not satisfy what i need exactly.

in this project i need to produce my own sine signal. if you have further comments, they will be all welcome.

 

[hi nash..did you find the answer of your question?i am also tryind to have a sintri wave form and still couldnt success..i also need helpif you have finished yours could you also help me?

 

Originally posted by nash@Dec 18 2004, 01:17 PM
hi;

i need a special waveform.it actually consists of the sum of a half wave rectified sine and a half wave rectified triangle.upto know is a pienut.

however if you want to have steady output on the cro screen,this way doesn't work. due to two different signal sources there exists phase shift so you can not get a stationary signal on the cro screen.

so i have to somehow obtain teh triangle signal from the sine input.

if you have any comments, i will be very glad.

thanks

[post=4183]Quoted post[/post]​

Mmm... High frequency and use a CRAPPY OpAmp with a terrible slew rate to act as a comparator. The frequency will be so fast that the OpAmp will never be able to saturate its signal and give you a Triangle wave. If you pick your compare voltage to be just under ground (use a pot) you will be able to time shift the triangle wave based upon the compare level. Low voltage will move the phase negative, while a higher voltage will take it positive.

I say use a crappy opamp because high quality ones will have a very good slew rate. If at all possible use an old 741. The 741, 741A, etc.

If you can't go this method then do the Sin into a comparator (square) into an integrator (triangle) and do the same thing with the comparator to change the phase.

MINOR changes in the comparator level will be fine. If you deviate to far from ground you will begin to introduce a DC offset and may want to add a cap at the output.