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Old 15th July 2004, 02:46 PM   #21
Cameron is offline Cameron  United States
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You know what else this would be great for?

Hint: Instead of 1kHz. How about 60Hz?

I2S to a nice DAC and a beefy output stage with lots of voltage gain. And you have yourself a absolutely pristine AC source for the rest of your equipment. You could have the anti-aliasing filter corner frequency set at something super low, like 240Hz. Any remaining digital noise would be far too low to measure.
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Old 15th July 2004, 03:19 PM   #22
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Yes ! For your Microwave. The food will taste much better !

;-)

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Jobstens
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Old 15th July 2004, 05:50 PM   #23
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Quote:
Originally posted by Cameron
You know what else this would be great for?

Hint: Instead of 1kHz. How about 60Hz?

I2S to a nice DAC and a beefy output stage with lots of voltage gain. And you have yourself a absolutely pristine AC source for the rest of your equipment. You could have the anti-aliasing filter corner frequency set at something super low, like 240Hz. Any remaining digital noise would be far too low to measure.

If you do build it, you might want to consider a sample rate a bit less than 44100Hz.
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Old 15th July 2004, 07:40 PM   #24
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Originally posted by rfbrw
If you do build it, you might want to consider a sample rate a bit less than 44100Hz.
That's well advised because jobstens' circuit won't work at 44100Hz.
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Old 15th July 2004, 07:46 PM   #25
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You would be better served considering the instruction cycle time of the microcontroller you intend to use.
i have some fast enough MCs here... But an old CDP is cheap and easy to use for this.
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Old 15th July 2004, 09:13 PM   #26
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Quote:
Originally posted by jbokelman


That's well advised because jobstens' circuit won't work at 44100Hz.
Why ? You only need more ROM.
60 Hz@44100 - one wave is 735 Samples long. That's 11760 Bits - You need a 27128.


But for this project I would prefer fs=192kHz with 24Bit.
I also would add two channels for threephase - that's better for the car-lift (or something ...) :-)



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Jobstens
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Old 15th July 2004, 09:23 PM   #27
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I also would add two channels for threephase - that's better for the car-lift (or something ...) :-)
besides all my woodworking machines need 3phase, my next Zen lites power supply does so.
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Old 15th July 2004, 09:53 PM   #28
Cameron is offline Cameron  United States
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I would also stick with a higher frequency sample rate. Otherwise you won't get the benefits of massively filtered and clean output. If your corner frequency is 240Hz, the drop at 60Hz is like .01dB, but at 352.8kHz (for 44.1kHz), the drop is huge. That's over 10 octaves. Even a simple 2 pole filter would then yield roughly 126dB down.

Another modification might be to synchronize the synthesized 60Hz with the line, compare the two, and amplify a difference signal. That way, the vast majority of the power comes straight from the line, but you still get stupid clean power at the output. You would still need a fairly decent power output stage capable of RF frequencies. Otherwise it would not be able to cancel out RF in the line.
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Old 16th July 2004, 01:39 AM   #29
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Quote:
Originally posted by jobstens
Why ? You only need more ROM.
The size of the ROM is not the problem. But, hey, you're the expert with 26 years experience. I'm sure you wouldn't post a design for others to copy if you hadn't first built it and verified that it works. Right? Or at least done a thorough desk check to verify that, considering the access time of the ROM and the setup requirements of the DIT, the 4040 ripple counter could settle a 13-bit address with time to spare.

What's going on here? It looks like a bunch of analog weenies playing with DACs and nobody knows diddlysquat about digital circuits. As I said, this web site should be called cseAudio and this forum should be called SingleChipDACAudio because anything beyond connecting a CS8412 to a TAD154x is unfathomable.
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Old 16th July 2004, 03:06 AM   #30
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At 24/192 thats a lot of samples and at 352.8KHz things are starting to get excessive given that a small microcontroller and a pair of R/C filters would suffice for a turntable. But since the engineers have obviously kidnapped the accounts department and the financial director,replacing them with robots, abandoning all sense of restraint along the way,lets go crazy.
On a more serious note, why use audio sample rates? I would chose a convenient number of samples per quadrant and derive the sample rate from that.
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