KC PCB layout
Beware a too short distance couples the output back to the oscillator. Been there, done that.
(don't agree with Guido's decoupling guidelines, have seen his PCB)
😎
tubee said:
Beware a too short distance couples the output back to the oscillator. Been there, done that.
(don't agree with Guido's decoupling guidelines, have seen his PCB)
😎
tried to get a screenshot of Kwak 7 here, but failed. Only jpg, pdf, gif and such are supported.
Re: KC PCB layout
Hi Elso
Since we may learn from you
- At what specific point do you disagree
- What is your proposal to improve
best
Elso Kwak said:
Hi Elso
Since we may learn from you
- At what specific point do you disagree
- What is your proposal to improve
best
Re: Re: KC PCB layout
Bypass caps should be placed directly at the supply pins, connecting to the groundplane.
http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1154,C1009,C1028,P1219,D4138
and various Analog Devices application notes😎
Guido Tent said:
Bypass caps should be placed directly at the supply pins, connecting to the groundplane.
http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1154,C1009,C1028,P1219,D4138
and various Analog Devices application notes😎
Re: Re: Re: KC PCB layout
Elso,
The fact that semi manufacturers reccomend swomething does not prove anything, at least not to me. Never trust what they write on paper !
When you place the decoupling at the Vcc pin:
1 - the loop area does not change, so no advantage.
2 - the common impedance in the ground plane, carrying the decoupling current, increases hence the voltage gradient across the groundplane increases too. This in turn increases crosstalk (and induces jitter) and RF emissions. A major disadvantage of your proposal, unless you don't care about signal integrity.
To prevent this, it is easiest to place the decoupling as close as possible to the ground pins. Experienced layout people have several ways out, but my guidelines are written for DIY community (though many manufacurers may learn from them) and therefor I gave simple though robust solutions.
I challenge you to carry out measurements to see the effects of what you advocate. Once the results are there I look forward to continue the discussions.
best
Elso Kwak said:
Elso,
The fact that semi manufacturers reccomend swomething does not prove anything, at least not to me. Never trust what they write on paper !
When you place the decoupling at the Vcc pin:
1 - the loop area does not change, so no advantage.
2 - the common impedance in the ground plane, carrying the decoupling current, increases hence the voltage gradient across the groundplane increases too. This in turn increases crosstalk (and induces jitter) and RF emissions. A major disadvantage of your proposal, unless you don't care about signal integrity.
To prevent this, it is easiest to place the decoupling as close as possible to the ground pins. Experienced layout people have several ways out, but my guidelines are written for DIY community (though many manufacurers may learn from them) and therefor I gave simple though robust solutions.
I challenge you to carry out measurements to see the effects of what you advocate. Once the results are there I look forward to continue the discussions.
best
Good!
Please go on! 🙂
(Of course Walt Jung & Jim Williams do not know what they write about, don't they?) 🙄
Please go on! 🙂
(Of course Walt Jung & Jim Williams do not know what they write about, don't they?) 🙄
Re: Good!
Elso
You may keep hiding behind names, that does not impress me at all. I have carried out measurements for years and years, and the facts are there.
Did YOU measure ?
Elso Kwak said:
Elso
You may keep hiding behind names, that does not impress me at all. I have carried out measurements for years and years, and the facts are there.
Did YOU measure ?
Other way around
Oh, I do it the other way around.......😀
Not that measurements interests me much. Now it's jitter spectrum, distortion spectrum in amplifiers, next year it is? Any correlation with listening experience? I play just a piece of clavichord music.......Pretty hard to reproduce faithfully.......If it gives me the jitters........ I run.......
Oh, I do it the other way around.......😀
Not that measurements interests me much. Now it's jitter spectrum, distortion spectrum in amplifiers, next year it is? Any correlation with listening experience? I play just a piece of clavichord music.......Pretty hard to reproduce faithfully.......If it gives me the jitters........ I run.......
Re: Other way around
my dear Elso,
In a few posts you have been able to fully distract from the initial subject. The discussion was about the best placement of decoupling capacitors. I gave one very important argument why I place them close to the Vcc pin (to maintain the ground as an equipotential plane where reference serves as reference)
Other then quoting what other people have stated, and some non scientific arguments, I have not seen any fundamental reason why it is beter to place them at the Vdd pins.
If you trust your ears, i am fine with that. I don't fully trust my own, have been fooled many times, as everyone, I guess.
Elso Kwak said:Oh, I do it the other way around.......😀
Not that measurements interests me much. Now it's jitter spectrum, distortion spectrum in amplifiers, next year it is? Any correlation with listening experience? I play just a piece of clavichord music.......Pretty hard to reproduce faithfully.......If it gives me the jitters........ I run.......
my dear Elso,
In a few posts you have been able to fully distract from the initial subject. The discussion was about the best placement of decoupling capacitors. I gave one very important argument why I place them close to the Vcc pin (to maintain the ground as an equipotential plane where reference serves as reference)
Other then quoting what other people have stated, and some non scientific arguments, I have not seen any fundamental reason why it is beter to place them at the Vdd pins.
If you trust your ears, i am fine with that. I don't fully trust my own, have been fooled many times, as everyone, I guess.
Re: Re: Other way around
That's an interesting, if not a little worrying, statement to make. Surely you either like what you hear or don't.
Does it, for example, mean that when Jocko listens to something he has built and it makes him want to shoot hippies the reality is he likes what he hears but would just rather shoot hippies ? I can see how the eye can be fooled but not the ear.
Guido Tent said:
That's an interesting, if not a little worrying, statement to make. Surely you either like what you hear or don't.
Does it, for example, mean that when Jocko listens to something he has built and it makes him want to shoot hippies the reality is he likes what he hears but would just rather shoot hippies ? I can see how the eye can be fooled but not the ear.
Jocko just likes to shoot hippies.
The ear can't be fooled, nor can the eye, but the brain that processes them sure can.
The ear can't be fooled, nor can the eye, but the brain that processes them sure can.
Re: Re: Re: Other way around
Hi rfbrw
The difference is (how I look at it)
1 - what you like
2 - what is most acurate
There is a bunch of people that like the typical tube sound of badly designed tube amps, because it gives a big cloud of spacious sound. I don't like that.
For the same reason some people don't like the sound of my filament modules, because it takes away colorations that they are used to.
I can make oscillators (by adding specific amounts of jitter) that will please everyone, but won't help in the search for acuracy.
It is a matter of taste, and what you're after. The ear is enough in case 1, but one needs more than that in case 2.
best
rfbrw said:
Hi rfbrw
The difference is (how I look at it)
1 - what you like
2 - what is most acurate
There is a bunch of people that like the typical tube sound of badly designed tube amps, because it gives a big cloud of spacious sound. I don't like that.
For the same reason some people don't like the sound of my filament modules, because it takes away colorations that they are used to.
I can make oscillators (by adding specific amounts of jitter) that will please everyone, but won't help in the search for acuracy.
It is a matter of taste, and what you're after. The ear is enough in case 1, but one needs more than that in case 2.
best
SY said:
Thought that might be the case.
Still don't see how the brain can be fooled. You hear what you hear. Sounds good you like it. Sounds like Pink Floyd, you don't. End of story. Unless the brain somehow changes between between listening sessions I can't see how the aspects originally found agreeable or disagreeable can be reversed.
Just like there are optical illusions, there are audio illusions.
Things like continously rising tones that actually cycle.
The ear(hearing) can change in hours of listening.
My experience is if something measures bad it has to sound inaccurate.
Tom
EE
Things like continously rising tones that actually cycle.
The ear(hearing) can change in hours of listening.
My experience is if something measures bad it has to sound inaccurate.
Tom
EE
Jocko
Jocko won't even shoot a squirrel, let alone a hippy...
Later
( And he can't aim )
😀
SY said:
Jocko won't even shoot a squirrel, let alone a hippy...
Later
( And he can't aim )
😀
Re: Re: Re: Re: Other way around
When it comes to pleasing the senses I just don't see why one would give Item 2 priority over Item 1. Surely no one ever says "Can't stand the sound of the thing but man, it is accurate"
But then again I remember when I was knee high to a grasshopper and I was introduced to a bland looking clear liquid, might have been called ooze or something like that, and asked if I wanted to try it. I instantly spat it out and said what I thought of it only to be told it was indeed a foul tasting liquid but it was an acquired taste. Why, I asked, would one want acquire such a taste and approaching 4 decades later I'm still waiting for an answer.
Guido Tent said:
When it comes to pleasing the senses I just don't see why one would give Item 2 priority over Item 1. Surely no one ever says "Can't stand the sound of the thing but man, it is accurate"
But then again I remember when I was knee high to a grasshopper and I was introduced to a bland looking clear liquid, might have been called ooze or something like that, and asked if I wanted to try it. I instantly spat it out and said what I thought of it only to be told it was indeed a foul tasting liquid but it was an acquired taste. Why, I asked, would one want acquire such a taste and approaching 4 decades later I'm still waiting for an answer.
strogg said:
Hi strogg, Is the FET powered from the raw supply, or is the drain connected to ground??? Has C8 ground? Where is L1 going? Double sided PCB???
I don't see the decoupling caps of the comparator IC going to ground....
For Guido: the decoupling cap of the FET is a "mile" away from the drain and a long narrow meandering groundtrace going back to the ground......
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