Digital Sine Wave Generation

Wendy

Joined Mar 24, 2008
22,703
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
 

crutschow

Joined Mar 14, 2008
28,541
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.
 

Ron H

Joined Apr 14, 2005
7,014
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)
Scott, can you post a schematic of the
4bits sinewave DAC (16 digits)
The resistors as 10K,20K,40K,80K,80K,40K,20K,10K
?
I can't see how it works.
 

ScottWang

Joined Aug 23, 2012
7,119
Scott, can you post a schematic of the
4bits sinewave DAC (16 digits)
The resistors as 10K,20K,40K,80K,80K,40K,20K,10K
?
I can't see how it works.
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.
 
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Ron H

Joined Apr 14, 2005
7,014
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?
 
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kubeek

Joined Sep 20, 2005
5,770
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.
 
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