If you want to limit the number of harmonics then you use a lowpass filter. A simple RC filter will not have much effect. You need an active Butterworth lowpass filter circuit with an order of at least 3.

 

Output of A opamp connected to 10k res, insted of Output B opamp.

Not sure why you would want to do that? --- If I understand your original intention correctly, it was to obtain a reasonable quality sine wave. The output from opamp A is a triangle. From opamp B a square wave.
The output filter has a Q of about 5, so is capable of producing a reasonable sine, especially from a triangle wave.
Inputting a square wave will make the filter less effective, and increase the harmonic distortion of the sine -the filter has to filter the fast edges of the square, as against the slow rise and fall of the triangle, which are much more 'sine like' to start with. The filter has to do less, and produces a more 'sine' like output.

If you need to change the amplitude of the output, just vary the feedback resistor of op amp C.

Glad I've been able to help a little with your project!

 

http://en.wikipedia.org/wiki/File:Cochlea_wave_animated.gif

Is it possible to generate these signals....
I got it from wikipedia..
http://en.wikipedia.org/wiki/Wavelength

it's varying wavelength and amplitude.. as well. .it might sound better... how can I generate.. these signals, OR is there any ckts to generate this..

 

Not sure why you would want to do that?

I agreee your post #12, is good... but my intenstion was, your ckts in post #45 differ to post #12.

 

http://en.wikipedia.org/wiki/File:Cochlea_wave_animated.gif

Is it possible to generate these signals....

You need a circuit that can vary the frequency and amplitude of the sine-wave.

 

You need a circuit that can vary the frequency and amplitude of the sine-wave.

Thankyou for reply....
Where can I start it... to built....what factors do I need to consider.. is there any better way.. or availability of chips to create.. those...signals..
Is there any ,material..to read.. bcos I tried to googled it.. but not much useful information info. abt this type of ckt build..

 

A long time ago there were analog ICs to make synthesized music but today they are gone. DSP ICs and programming for them are used today.

A microcontroller can make variable frequencies and change their amplitude.

You can use many parts to make an analog voltage-controlled variable frequency sine-wave generator and a voltage-controlled amplifier.

 

A long time ago there were analog ICs to make synthesized music but today they are gone. DSP ICs and programming for them are used today.

A microcontroller can make variable frequencies and change their amplitude.

You can use many parts to make an analog voltage-controlled variable frequency sine-wave generator and a voltage-controlled amplifier.

OooH.. I have to implement.. other...things I think.. Thanks for info.. where can I start,... audioguru.....!
Help me....

 

OooH.. I have to implement.. other...things I think.. Thanks for info.. where can I start,... audioguru.....!
Help me....

Sorry.
I have never designed a music synthesizer.

 

Certainly the circuits used in an analogue music synthesiser will contain all the building blocks you need to vary oscillator frequency, harmonic content, amplitude variation ---in short, sound synthesis!!

The schematics and circuit descriptions here: http://www.freeinfosociety.com/electronics/schematics/audio/moogprodigy.pdf

contain all the bits you might need --it's just a question of picking out what you want, and trying it out!

(The schematic is right at the bottom of the document, BTW.)

And I can confirm that the Moog Prodigy is capable of some great sounds --I've had one for over 20 years!

 

I agreee your post #12, is good... but my intenstion was, your ckts in post #45 differ to post #12.

I see what you mean --post #45 was my first attempt at 'sim' software, and I've drawn it wrong. Actually works better than I would have thought!

I can't see how you would measure the sine wave THD percentage with the sim software, so you can't easliy compare the two versions. Should be easier with actual breadboard version. You might even actually hear a slight difference in the purity of the sinewave --must try it one day!

I've attached a sim of the oscillator with optimised values --note the changes in values of R3 and R8, plus the addition of R7. Also the input to the filter is now taken from the triangle output, as it should have been before - not from the square wave output!

 

I made an oscillator with some Cmos digital inverters and a Cmos CD4018 Johnson counter. The signal was a sine-wave made with 10 steps.
You can call it a signal that is 10 times over-sampled.

Then I filtered it with a 8th-order Butterworth lowpass switched-capacitor filter IC.
The output had distortion of only 0.01%.

 

It's been two week(i tried in other wayss. to generate harmonics.. )..sorry for delay...
I need one more ckt idea.. to generate. 600Hz audio signal...

Now I am considering volume control... as one more input to my OSC or audio amplifier LM386.
Now I am not worrying abt sine wave.. or squarewave(easier I think..)

Soo, finally , one input as switch on/off oscillator and second input as volume control.. (0 to 5V). output of opamp ckt have to drive LM386 amplifier .... any efficent ideas. let me know..
Please find attached document.

Thankyou in advance..

 

Your "volume control" will adjust the supply voltage to the opamp and oscillator but it will not adjust the volume of the sound.
A volume control is supposed to divide the signal input to the LM386 amplifier.

 

Your "volume control" will adjust the supply voltage to the opamp and oscillator but it will not adjust the volume of the sound.
A volume control is supposed to divide the signal input to the LM386 amplifier.

Yes I agree is there any other way?

 

Yes I agree is there any other way?

There are a few ways to make a volume control.
I showed the most common and simplest way.

 

There are a few ways to make a volume control.
I showed the most common and simplest way.

I tried your ckt, but it not controlling volume...

 

Of course my circuit controls the volume. It makes the input to the LM386 amp go from zero to max.

 

Of course my circuit controls the volume. It makes the input to the LM386 amp go from zero to max.

Thanky ou for reply.
Your ckt controls volume.. but I want to drive my speaker using two different inputs(one is volume controller(0to 5V variable) and other input as switch),As I posted.
Your ckt has only one input which controlling the oscillator and volume control using pot which i dont want because I already have 0 to 5V variable input source.

 

Your last circuit had only the sine-wave generator connected to the input of the LM386 amp. The variable DC did almost nothing and you never posted a circuit for it to do anything. The switched 5V turned the sine-wave generator on and off.