# Digital Sine Wave Generation

Discussion in 'General Electronics Chat' started by davyna, May 15, 2013.

1. ### davyna Thread Starter New Member

May 15, 2013
13
1
i didn't understood this circuit...need help!

Last edited by a moderator: May 15, 2013
2. ### Wendy Moderator

Mar 24, 2008
20,765
2,536
Congratulations,

Welcome to AAC.

Congratulations, you have practiced the arcane art of necromancy, the revival of a long dead thread. Likely the OP (Original Poster) has solved his problem in the years that has passed, or thrown it away, or something.

In adddition, a thread belongs to the OP (original poster). Trying to take over someone elses thread is called hijacking, which is not allowed at All About Circuits. I have therefore given you a thread of your very own.

This was split from need help understanding how digital sine wave circuit works

3. ### davyna Thread Starter New Member

May 15, 2013
13
1
How a timer and counter can generate sine-wave? help me..

4. ### crutschow Expert

Mar 14, 2008
13,003
3,232
The circuit is a crude Digital-Analog converter. As the switches are sequentially sequenced ON and OFF the output voltage will rise and fall in a stepped sine-wave with value determined by the voltage divider resistors connected to the ON output.

5. ### ScottWang Moderator

Aug 23, 2012
4,853
767
NE555 → 8 bits Counter(CD4520) → 4bits sinewave DAC (16 digits)
The resistors as 10K,20K,40K,80K,80K,40K,20K,10K

NE555 → 16 bits Counter(CD4520) → 8bits sinewave DAC (256 digits)
The resistors as 1K,2K,4K,8K,10K,20K,40K,80K,80K,40K,20K,10K,8K,4K,2K,1k

8bits sinewave DAC (http://www.lennard.net.nz/electronics/dac.html#r2r)

6. ### Ron H AAC Fanatic!

Apr 14, 2005
7,050
657
Scott, can you post a schematic of the
?
I can't see how it works.

7. ### ScottWang Moderator

Aug 23, 2012
4,853
767
Ron H, the method almost there, the linked page is only 4 bits(16 digits), the waveform will be only low to high, so it needs to adding the waveform from high to low, that's why I want to using 8 resistors.

if you felt that the circuit seems can't get a good sine wave, that's true, because the OP asked for a timer and counter can generate sine-wave, that's not a good way to generate a sine wave.

I have been designed a digital sine wave for a industrial product used, I can't post the details, but I can sharing the idea, there are somethings need to modify, when using a math to calculate and drawing the sine wave and to get the values of the waveform, and the frequency is fixed.

1. To get or write a program to drawing a waveform of sine wave and to get the 256 bytes data of the waveform, the data should be according to the input frequency.

2. When I get the data, I still need to modify the data, this is a boring and hard work, because I have to check each byte from 256 bytes, when the position of data is not right, then I have to change it, so I have to modify again and again.

3. The 256 bytes data of sine wave saved into the 8 data bits EEPROM.

Square wave → 8 bits Binary counter → sine wave EEPROM → 8bits DAC → Op Amp Waveform shaping → sine wave

The input frequency divided by 256, so the output frequency are equal to input frequency /256.

I'm not sure all the described is correct or not.

Last edited: May 16, 2013
davyna likes this.
8. ### Ron H AAC Fanatic!

Apr 14, 2005
7,050
657
Scott, I requested a schematic, but all I got was a lot of hand-waving.
Do the circuits you described in post #5 work, or not?

Last edited: May 16, 2013
9. ### THE_RB AAC Fanatic!

Feb 11, 2008
5,435
1,305
Does it have to be using a 555 and a counter? What did you need to make sinewaves for?

I did a project for a 1kHz "precision" sine generator, using a PIC to digitally make the sine wave using PWM;

http://romanblack.com/onesec/Sine1kHz.htm

Generally this is a much simpler circuit and will produce much better frequency accuracy and much better sine shape accuracy;

Ron H and davyna like this.
10. ### ErnieM AAC Fanatic!

Apr 24, 2011
7,386
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If you replace the EEPROM with RAM and make the clock adjustable you have the innards of an arbitrary waveform generator.

11. ### davyna Thread Starter New Member

May 15, 2013
13
1
hi, how can i obtain pure sine wave fro this wave
o get
I want to get the pure sine wave help me

12. ### kubeek AAC Fanatic!

Sep 20, 2005
4,670
804
since it is digitally generated it will never be a pure sine. You could try lowpass filtering it to reduce the harmonics. Or use more levels to get better approximation.

Aug 23, 2012
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