Someone please set upa GB for this board project?
I'd like to stay arm's length from the board GB since I am dealing with David's stuff with his widow. But please, would someone do a GB for this? There should be some small donation for his widow built in, just because I think it would be the right thing to do. I can provide contact information to the person who takes this up. Beyond that, I will not be involved just to keep everything clean.
This is the very low distortion oscillator that davada designed and has shown to work very well.
-Chris
I'd like to stay arm's length from the board GB since I am dealing with David's stuff with his widow. But please, would someone do a GB for this? There should be some small donation for his widow built in, just because I think it would be the right thing to do. I can provide contact information to the person who takes this up. Beyond that, I will not be involved just to keep everything clean.
This is the very low distortion oscillator that davada designed and has shown to work very well.
-Chris
Things are more complicated, error produced by DAC depends on a step size, difference between previous & new samples. So having calibration done with sawtooth waveform - constant steps - is not gonna to work with aperiodic random jumping.
Another issue is temperature and low frequency drift.
I've done some research with nucleo-H743 board, making "correction" to THD distortion, sine wave output constant magnitude. So far, I was able to get from initial -70dBc (12-bits internal DACs, two - primary and error zeroing) about -100dBc (better quality that my CS4354 could get, especially above 10kHz output). Adc is ad7984 PMOD evaluation module from AD. It would be possible too get -110 minimizing noise level.
Drift, temperature & aging effects I think 'd be possible to track using two couple of 12-bits DAC, repeating calibration subroutine continuously in interleaved fashion.
We now have the schematics available. Which I needed for any future repairs. There must be pcb file somewhere also. His computer?
I asked David to make one for me as we had many conversations about this and earlier HP339A mods.
I have SN 001.
THx-RNMarsh
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I took a quick look at David's (dlbSVO) design, it uses a 5V SPI interface to control a MPC23S09 chip & the AD5543 DAC, so it needs a MCU with SPI and some software for control. So there is that aspect to consider, it is not a stand alone unit based on the schematics as provided. I was not following that thread very much, so I might have missed how he did the control portion of the design.
Yes, it is software controlled via PC.
But I can copy that out of my memory/file.
A finished product Might be doable via Magnet Tech. In order for David to make one for me, he said he would need $2500 USD for the pcb development, parts and his labor. So..... ?? But, it is better than anything commercially available for a variable freq source.
For His family, I would also negotiate a royalty with a test equipment company like Khron-Hite etc to make it as their product. But, do so before making it all public domain.
THx-RNMarsh
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So, does that mean that Richard, that you can take pictures of the your finished SVO
so that the layout can be copied? Then, I guess it would need to be proofed/verified, etc.
Probably some tweaks here and there etc. A couple of prototype board runs and tested.
Make a good project also.
So, does that mean that Richard, that you can take pictures of the your finished SVO
so that the layout can be copied? Then, I guess it would need to be proofed/verified, etc.
Probably some tweaks here and there etc. A couple of prototype board runs and tested.
Make a good project also.
Richard, are you saying that you paid Davada $2500 for the development of yours?
Are you also looking for a financial return on your investment?
Then if a company like Krohn-Hite would make it, that would rule me out and others
from ever being able to afford one. Unless there is a short list made available to K-H, that would
specify cost pricing for early comers before public sale. Kind of like people that have
stock in companies before they go public. Which would be a good thing.
Cheers,
so that the layout can be copied? Then, I guess it would need to be proofed/verified, etc.
Probably some tweaks here and there etc. A couple of prototype board runs and tested.
Make a good project also.
So, does that mean that Richard, that you can take pictures of the your finished SVO
so that the layout can be copied? Then, I guess it would need to be proofed/verified, etc.
Probably some tweaks here and there etc. A couple of prototype board runs and tested.
Make a good project also.
Richard, are you saying that you paid Davada $2500 for the development of yours?
Are you also looking for a financial return on your investment?
Then if a company like Krohn-Hite would make it, that would rule me out and others
from ever being able to afford one. Unless there is a short list made available to K-H, that would
specify cost pricing for early comers before public sale. Kind of like people that have
stock in companies before they go public. Which would be a good thing.
Cheers,
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Yes, but you must be AD, TI, IBM etc. to buy a system. And it needs water cooling
with connection to the air conditioning of your building.
The simplest solution is to buy another, different FFT analyzer.
But then the man with two clocks does not know the time.
cheers, Gerhard
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Yes, sure I can make a photo of it. Yes, i paid david to build it for me. No, I dont want or need to get money for it back. Water under the bridge. I wanted it and at same time help david get some money and pcb layout done, So he could sell the pcb's for DIYers.
We need to find his pcb layout art work on his computer.
-Richard
I do not think that it is such a big job to do a new layout, helps to have a BOM for some things like the relays that were used. Even having the Gerber/drill data helps enormously to reproduce, if one wants to do a new layout in a different ecad program. I am uncertain what David used for ecad software or who did the design/layout. Certainly would help to get as much info as possible if one wants to reproduce or maintain the design.
What was the control software run on? Mcu? I would assume Arduino, but it could be many others. Having the source code is vital to mimizing the work to re-invent or maintain just like the h/w would be.
What was the control software run on? Mcu? I would assume Arduino, but it could be many others. Having the source code is vital to mimizing the work to re-invent or maintain just like the h/w would be.
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I think the reason it was done that way was to have galvanic isolation or the option for it. Another reason could be that the design is not tied to a specific controller. We or at least I am missing the control section of this design, it is incomplete as was presented or I need to do some homework and back track, investigate the design, if the information was posted.
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No, the simplest solution is a notch filter. To solve "chicken and eggs" problem - find out what part is guilty for THD distortion adc or dac - insert notch in between. Suppressing THD-2,3,..,n and observing fft output.
No, you don't understand that it is not necessary that both ADC and DAC are without fault.
It is sufficient that the ADC is "quite good" and that its errors can be corrected by
predistorting the data that go into the DAC. A DDS based generator can easily generate
the harmonics. Adjustable Amplitude is just a multiplier and a coefficient register, adjustable
phase is just an adder and a coefficient register.
When the test frequency is a synchronous subharmonic of the DDS clock, the sine table
collapses to a pretty short list since most values are never needed. Nowadays it could be
done in software - with a DMA transferring the list repeatedly to the DAC.
It is sufficient that the ADC is "quite good" and that its errors can be corrected by
predistorting the data that go into the DAC. A DDS based generator can easily generate
the harmonics. Adjustable Amplitude is just a multiplier and a coefficient register, adjustable
phase is just an adder and a coefficient register.
When the test frequency is a synchronous subharmonic of the DDS clock, the sine table
collapses to a pretty short list since most values are never needed. Nowadays it could be
done in software - with a DMA transferring the list repeatedly to the DAC.
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