Pulse Train to Sine Wave help?

[GregSmyth]

Hello I am trying to convert a pulse train signal to a sine wave, or close as possible to a sinusoidal wave. I am trying to output the frequency that the pulse train carries to a speaker that will generate the sound associated to the frequency. (Tryin to make an audio sound from the pulse train)

I am currently using an DAC chip and a voltage to frequency chip.

Is there any way to accomplish this with a more basic/cheaper circuit?

The output has to sound close as possible to the actaul note.

Thanks
Greg

 

[hyedenny]

There are a number of different ways to implement a sine wave generator... To get a clean "note", Im assuming you mean no harmonics. Heres a good circuit that might fit what you need:

**broken link removed**

 

[GregSmyth]

that looks like it would be perfect, but the only input I could give it would be pulse train (no negative values) wave, not a full square wave, if i could gain the negative parts back from the pulse train I could use it right?

Thanks for the post!


Basically I am trying to convert an 8-bit binary number to a sinusoidal frequency for a speaker. The ouput from my DAC is from 0v to 5v in steps of around .020v increments and I need to implement sine waves from 200Hz-1000Hz. And I just cant determine how to convert the output voltage to a frequency. If there is an easier way to just control frequency with a voltage that would be ideal.......

I want to input 00000000 and get 200Hz, and 11111111 and get around 1000Hz (or less)

amplitude for the frequency wouldnt really matter in the conversion, i could just put it through an audio op-amp

Thanks for the help

 

[hyedenny]

Hi again,
Do a google search for a "tuned circuit bandpass filter" and see what you come up with...
I would consider using a PIC with a built-in DAC. That would take care of everything at once, and software adjustability is only a PC away!
Are you using a MIDI? It sounds like it may be fun.

 

[Russlk]

You can make sine waves most easily with a microcontroller. Take a look at Don Lancaster's website: www.tinaja.com, and particularly: https://www.tinaja.com/magsn01.asp. I have tried the "magic sinewaves" and it works.