Hi and thanks again.
I have already played with LTspice .. and give-up. It is difficult to use it properly. It is for educated people for sure.
Designing is not a trivial task for sure.
Modifying something of existing maybe a little easier.
In the meantime i have found another article praising the EI type x-former versus toroidals ...
SoundStage! Max dB - The High-End Mythology of the Toroidal Power Transformer (07/1998)
Thanks again, gino
Here's one with a bit of both:
http://www.diyaudio.com/forums/pass-labs/16337-ei-vs-toroidal-transformers.html
Would really like one but has not invested in a scope a bit out of budget for good quality ones but they are getting better and cheaper. Invaluable tool for more serious work, i'm just a humble DIYer. Been keeping an eye on Rigol DS1054Z (hackable to 100MHz)
New Rigol DS1054Z oscilloscope - Page 1
http://www.diyaudio.com/forums/equipment-tools/274248-choosing-instek-scope.html
http://www.diyaudio.com/forums/pass-labs/16337-ei-vs-toroidal-transformers.html
Would really like one but has not invested in a scope a bit out of budget for good quality ones but they are getting better and cheaper. Invaluable tool for more serious work, i'm just a humble DIYer. Been keeping an eye on Rigol DS1054Z (hackable to 100MHz)
New Rigol DS1054Z oscilloscope - Page 1
http://www.diyaudio.com/forums/equipment-tools/274248-choosing-instek-scope.html
Hi and thanks a lot again for the link. Actually there are some statements that i have found also myself on other articles.
But i have a very basic question ... with the right scope is possible to see this bloody noise ? if so why not put some pictures of the noise ?
I like to see pictures like this one ... even if i cannot see the axis ...
An externally hosted image should be here but it was not working when we last tested it.
so it is possible to see how good is a power supply.
Then we can discuss about the noise vs. Hz ...
by the way i think that with the right filtering networks the noise can be kept low also at high Hz.
An externally hosted image should be here but it was not working when we last tested it.
Yes i have arrived at the same conclusion that a good scope is a must.
I have read now about my scope here ... it is cheap and limited.
The idea is to play a little with it and see if i get interested.
Then 4-500 USD can be spent for a very fundamental tool.
It must be seen as an investment.
I understand it is the only way to really check the quality of circuits.
A good scope can tell a lot of interesting things indeed.
Thanks again, gino
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Hi and thanks a lot for the helpful advice. a shunt regulator to be placed where ?
I am a little ignorant ... before the regulator on the pcb ?
Thanks again, gino
Hi and just to say another opinion.
I see many many words spent in the technical articles in the audio magazine.
This is educational of course, but i think not in the right way.
Because it does not sustain the statements with evidences.
For instance if the aim is to show the better HF noise rejection of EI type transformers vs. Toroidal ones why not put just two pictures taken from a scope ?
they could send in a combination of high HZ signal, like 50k, 100k and 400k and show what comes out from the transformer on the scope ?
That would be really educational i think.
And also it would be a big punch in the kidneys of the subjectivist "only by ear" testers.
And they would suggest a more technical approach to problem solving.
I wonder how many of these reviewers have actual experiences in using of a scope.
It should be bought even before the soldering iron i think.
One day i will have one like the Rigol mentioned.
Nothing NASA level. Just a decent entry level for hobbyst.
Thanks a lot again for the always valuable advice.
It made me think a lot. Maybe too much ?
Kind regards, gino
I see many many words spent in the technical articles in the audio magazine.
This is educational of course, but i think not in the right way.
Because it does not sustain the statements with evidences.
For instance if the aim is to show the better HF noise rejection of EI type transformers vs. Toroidal ones why not put just two pictures taken from a scope ?
they could send in a combination of high HZ signal, like 50k, 100k and 400k and show what comes out from the transformer on the scope ?
That would be really educational i think.
And also it would be a big punch in the kidneys of the subjectivist "only by ear" testers.
And they would suggest a more technical approach to problem solving.
I wonder how many of these reviewers have actual experiences in using of a scope.
It should be bought even before the soldering iron i think.
One day i will have one like the Rigol mentioned.
Nothing NASA level. Just a decent entry level for hobbyst.
Thanks a lot again for the always valuable advice.
It made me think a lot. Maybe too much ?
Kind regards, gino
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A scope is not good for showing small differences.
It is very good for showing gross differences.
A DSO can do this very well if it has the resolution to show what you want to measure.
Often we need to extract the big background signal and look at the remainder.
eg, using a DC blocking capacitor and the scope probe to look at the ripple on a DC supply rail. This technique is so useful that a scope has both AC coupling and invert/subtract built in.
You need a method that reveals the noise/interference and then you can compare.
It is very good for showing gross differences.
A DSO can do this very well if it has the resolution to show what you want to measure.
Often we need to extract the big background signal and look at the remainder.
eg, using a DC blocking capacitor and the scope probe to look at the ripple on a DC supply rail. This technique is so useful that a scope has both AC coupling and invert/subtract built in.
You need a method that reveals the noise/interference and then you can compare.
sorry .. what do you mean by gross ? can i see mV at 200kHz ?Noise. I have declared war to noise. HF noise in particular.
The only things that interests me today are dacs and similar devices.
Digital. I am only and absolutely and forever digital.
I cannot touch a LP, a tape ... i am allergic
because i am sure a very good digital sound is possible. and i would like to get that one day.
Thanks and yes. I want to look for noise.
I have seen a demo on youtube so basic that i have even understood that myself.
The issue is simple. The music signal is like a series of objects place on a carpet (the noise).
If the carpet is thick the smallest objects cannot even be seen because they are sunk in the carpet.
And these small objects are the details in sound.
In the end the lower the noise the best the sound. Ever.
The noise can enter from the mains and/or be generated internally in the unit.
So the ps must sit between filters.
I want to see noise.
Thanks again, gino
Hi and thanks and this is fine. To see it it is already a really great thing.
But i think, maybe i am wrong, that we are able to see not only the presence but also the nature of noise. For instance its spectrum vs. Hz, that is what intrigues me much more.
Then if we see noise at HF at the ps out we can discuss about its origin.
Usually it comes unfiltered by the mains.
Or it could be generated by some parts inside the ps, like diodes.
With a scope for instance i could see cleary, i hope, the effect of changing rectifying diodes with special ones like Schottky.
I could select the best parts for any application in this way and see the effects of any mods and learn through the scope what is good and what is bad.
Let's say that a 1st screening can be done on the basis of reading datasheets. And only then using the scope.
Maybe i will have a excellent noise filtering before the transformer and then a very noisy diodes bridge that ruins everything
Maybe placing a particular combination of caps across the diodes bridge will tame a lot its noise. And the scope will tell me this. It will show me this.
Main problem is that i am always on the move.
I cannot embark in a long term project.
Thanks a lot again, gino
Well also what kind of noise is (i.e. noise spectrum).
Not all the noise is equal.
A good example of no noise ...
http://www.exasound.com/portals/0/Images/e12-Measurements/exaSound-e12-DAC-Noise-Floor.jpg
Regards, gino
gross = very big (probably from the imperial unit 144off)
Gross (unit) - Wikipedia, the free encyclopedia
Gross (unit) - Wikipedia, the free encyclopedia
for an example of rCRCRC filtering see
http://www.diyaudio.com/forums/anal...-80-ebay-pcbs-power-train-35.html#post4352394
http://www.diyaudio.com/forums/anal...-80-ebay-pcbs-power-train-35.html#post4352394
Hi yes but in terms of V ... mV, uV ?
for instance ... they say that some regulators have a residula noise at the output of the order of tenth of uV ... can i see this noise or is too little ?
then we can discuss if it is important that the noise is this little ...
Anyway as a 1st experiment i will try to connect it and measure the noise out of some cheap SMPS i have ...
the idea is to rank them from the noisiest to the most quiet.
SMPS have usually ripple in the range of tenth of mV ... even hundreds of mV the worst ones.
If only i will be able to do this i will be repaid immediately of the cost of the scope (not much actually ... 60-70 USD).
Then i could move up maybe.
I have to measure some of these cheap ps first.
Thanks again. gino
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Hi and thanks for the link.
Yes this is what i would like to do one day, but only with low V and low VA ... 24V max and 1A max ...
I am at the moment, and maybe also in the future, interested exclusively in ps for dacs and very less line preamp ... and stop.
I had to focus and i am now focused.
So i will ask and read about power supplies parts and testing.
My only dream now is to be able to one of those wonderful noise spectra down to ... 120db ?
on my pc screen Can i do that with this unit here ?
Hantek 6022BE PC Based USB Digital Storag Oscilloscope 2 Channels 20MHz 48MSA S | eBay
Thanks again a lot indeed.
Kindest regards, gino
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reading better than 1% is doing well with a scope.
1% distortion in a sinewave will be "not easy" to read.
1% of noise on a bigger signal will be "not easy" to read.
You cannot do small signal examination on a scope.
You need to subtract out the big signal to "SEE" the remainder/residual.
if you have a 20Vdc supply rail with 10mVac (~30mVpp) ripple on that big signal. You have a wanted signal that is 0.15% (30m/20) and it won't show on a DC coupled scope.
AC couple and change the scale from 5V/div to 5mV/div and the small AC signal will show up easily. But you had to subtract the 20Vdc with the DC blocking capacitor to see the 0.15% signal.
If you had a 1mVpp ripple/noise on the 5Vdc supply, what would you see?
Not much !
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Hi again. This is a good news.
This is what i want in the end. A mV sensitivity will be enough.
I am not looking for uVs at all ... just gross
However i really hope to find a tutorial somewhere with advice on how to set up a testing rig and build a load.
I am really curious to see the noise of these ps. I am sure they are not made equal ... i am sure of this. Some must be better than others.
That would an interesting 1st experience indeed.
Thanks again, gino
Am i wrong of this dc block feature should be provided as standard on a scope ?
it is the first need that comes to my mind ... i mean, it sounds to me as a very basic need.
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I use a 2mV/div scope.
I cannot see 1mVpp of noise after subtracting the big signal.
All I have is a wider line where a thinner line should be, indicating there is noise and other interference on the big signal.
A scope won't measure noise of <1mVpp.
You need completely different tools to measure and compare noise levels from different circuits.
Look up Frex
http://www.diyaudio.com/forums/equi...llivoltmeter-recommendations.html#post4003402
or
LNA (low noise amplifier)
I cannot see 1mVpp of noise after subtracting the big signal.
All I have is a wider line where a thinner line should be, indicating there is noise and other interference on the big signal.
A scope won't measure noise of <1mVpp.
You need completely different tools to measure and compare noise levels from different circuits.
Look up Frex
http://www.diyaudio.com/forums/equi...llivoltmeter-recommendations.html#post4003402
or
LNA (low noise amplifier)
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