Major Midibox error, bypass capacitors!

[KD]

Hi  folks and Torsten!

As usuall i dont have the time to wade trough the archives so please

be patient with my mails if this has been allreday discussed at the forum.

I have been going trough all the design schematics and got a bit supriced!

Every schematic (exept OPL3) has a major error, the lack of "bypass capacitors"!!!!

Long Cabels:

Cabels by default contains a small part of inductance, i.e are inductive,

curl the cable some turns and you create a Q point of varying magnitude,

now run a CLK from , eg the core module to a HC595 a  some distance

away or so now if Q are high and "in tune" with CLK you can get resonances

wich in turn scrambels data, another thing is the impedance matching from

core to HC595, if miss matched and rise and fall time are fast enough you

will get signal bounching wich will guarenteed scramble data!!

In either case by not taking care of this wll limit future development of

increase of CLK speeds and improwment of timing can show to be impossble

to implement!

Thats the background and it needs a adequate cure!!

Do this::

One 100nF cap for each device.

One 10uF cap (standard elyt) for every five devices.

Led boards:

For boards who drive LED's a 10-100uF/5V for every board would do, if

voltage are pulsating or got rippled by speeded switching increase cap.

Analog boards:

Boards who deals with analog audio or CV voltages, you really need to

place attention to cirquit layout and decoupling if you want high performance.

In the case of long cabels between POT and 4051 you can try to use screened

cable with one end screen left open. If thats not working place a 6db RC low pass

net between every 4051 output and core AN input,(consists of a 100ohm and

a 1-100nF cap, R passes signal C shorts AC to ground).

However this needs knoweledge of the input capacitance of the PIC18F analog muxer

inputs it migh be so that the Ron in 4051 is enough combined with the capacitance

of the 18F its self.

Socketing:

And contrary to whats said ""i wouldent socket the 4051 muxes"" in time and

wether sockets will corrode , solder the 4051 they are rugged you wont

blow them as long as your input voltage are withing range of the suply voltage.

Actually dont socket anything, expect perhaps the MCU!

Sadness:

Now, dont be sad, a  simple solution for the cap requirements is to go out

and buy a bunch of 0805 size surface mounted 100nF caps and solder

close to +V bridge the other cap end to GND witha fat wire!

Hope this design help will enlight you in your course of building!!

Reg

KD

[Martin_Haverland]

whooops!

seems that you are right. it's a major design flaw.  :'(

maybe we will need new pcb layouts taking decoupling caps into account to make the midiboxes more stable... :P

grrr... ???

thanks for your revision of the mbhp modules.

i would be very interested in a comment from thorsten, if he would mind to change the schematics ...

martin

[Duggle]

hi,

I think the lack of bypass caps has been noted before. it is standard engineering practice and should be followed. However,

I don't know of a case where this has caused problems with MBHP projects. Many of the basic modules (Din, Dout,Core ) have been in service for some years now, so we know they work reliably. Having said that, when I built my MB64 over 2yrs ago I included at least a few 100nF monlithic ceramic caps, on each board mounted directly across the power rails. It is easy to retrofit ceramic caps (either SMD, or leaded variety), so I think a redesign is really uncalled for. Perhaps something to think about including in future designs, or if a board is being redrafted, though.

cheers

[TK.]

Hi,

there are very obvious reasons why I left out the bypass caps on most modules: I was forced to limit the PCB area so that it fits with a euro size board. This was due to Eagle freeware license limitations (e.g., it isn't possible to create a board which is larger than 100 mm), and due to the yield (number of modules which can be made from one euroboard) which was a requirement from Mike to keep the costs low. I think that SmashTV has the same requirements - please correct me if I'm wrong!

So, my idea was, if additional caps are really required, then they could be mounted at the bottom of the PCB. Since MBHP will never go into a professional production, where manual effort counts, I thought that this would be an adequate solution. But then I did some experiments with chained DINX4 and DOUTX4 modules and noticed no problems even without caps - also no "beta tester" reported problems - so I left them out from the schematics (my general worldly wisdom: so long nobody proves the converse, I don't believe it ;-)

I learned in university that bypass caps are required to store and release energy on high current peaks. Leaving out the caps can lead to EMI issue, e.g. short low-voltage bursts at neighboured gates which affect the functional behaviour, or emitted signal noise on analog circuits. That impedances/resonance frequencies between the gates and wires can also play a role, was new to me - it sounds disastrous, but I have to read some literature before I can give a statement on this. Are you sure that this is not an issue of HF logic and/or high power designs only?

Ok, I also have to say that at the beginning where I defined the MBHP my focus was on digital data processing, where signal noise doesn't hurt so much like on mixed signal designs, so long frequencies are relatively low (< 50 MHz) and the TTL levels are stable. Using analog circuits (like the SID, AOUT, OPL3) was a new field which came later, and which was not taken into account from the beginning. Not sure how the MBHP would look today if it would be designed from scratch. As Duggle mentioned: it makes sense to consider such things on future designs.

However, if somebody thinks that he can reduce jitter on the analog inputs or background noise on the SID by following this suggestion, then add 10nF or 100nF caps at the Vss/Vdd pins of each IC from the bottom + one 10 uF per module (or 100 uF for modules with high current consumption like mentioned above), but from my experience it won't solve the problems. Perhaps you will notice absolutely no difference - bypass caps cannot reduce glitches and spikes, and they also don't help to eliminate ground loops and all those disturbing factors. Maybe I should also mention that I don't hear any additional noise frm the SID when all 99 LEDs of the control surface are toggled with different frequencies. Why? Because the SID power lines are wired starlike from the PSU. Seems that this was sufficient. However...

Karl, I must say that I'm happy about your posting. It's an important reminder (I swear that the next MBHP modules will be littered with bypass caps in future ;-) and contains some interesting informations about pot wiring, 4051 muxing, sockets too

Sidenote: the jitter monitor application from the MIOS download page demonstrates that caps against ground or shielded cables won't improve the signal quality here - maybe because of the reduced ADC resolution of 10bit. The jitter is normaly 1 bit, and this is caused by the 1/2 LSB error which can be found on any ADC. Sometimes I think that people are just too afraid that they are doing something wrong when they are "violating" such rules which are common in other design areas.

This comment should not decrade your input!

Best Regards, Thorsten.

[Martin_Haverland]

thank you very much for the detailed comment on the above mentioned issues.

I think you're absolutely right that star grounding is one of the turn keys (or a "secret" weapon) of the successful making of quality analogue audio circuits and probably much more important than the bypass capping.

(i've "modded" some studio gear with slightly flaw designs by simply doing a good stargrounding with immediately hearable results. even more relevant than changing opamps, vca's or re-capping .)

and yes: every "design rule" is just as important as it proves in the real lives implementation  ;D

but as it turns out that we will have more and more mixing of analogue and digital circuits (as it seems to be a major interest of the midiboxers), KD's mentioned issues maybe of great importance for the future development of possibly more complex applications with for example integrated DA - filter - chains....

(sorry if bad english...not my day... ;))

very interesting thread....thank you both...

Martin

[KD]

Hi.

I feared that this situation should occur! I will try to be pedagogic about it!

I have 20+ years of electronic enginering, i have designed many embeedded systems,

very high speed optical transmission system 900Mhz up to 8Ghz, real time ASIC

emulators at very high speed, huge amount of analog signal processing devices.

I have once been working at R/D at one of the largest mobile companies around

as a design engineer and as a PCB engineer doing mixed LF,RF and power RF

design.

I have been there, see it, done it, (typical engineer slogan) im not a super

engineer , im not even a engineer, and i dont even pretend to be one,

however, i do think i know what im talking about, you simply dont do

what you suggest, its simply not an adequate design procedure.

>there are very obvious reasons why I left out the bypass caps on most modules:

>I was forced to limit the PCB area so that it fits with a euro size board. This was due

>to Eagle freeware license limitations (e.g., it isn't possible to create a board which is

>larger than 100 mm), and due to the yield (number of modules which can be made

>from one euroboard) which was a requirement from Mike to keep the costs low.

>I think that SmashTV has the same requirements - please correct me if I'm wrong!

If thats the reason, then it was a bad design desicion!

Sorry, but not a good excuse im afarid!

>So, my idea was, if additional caps are really required,

>then they could be mounted at the bottom of the PCB.

Its not if they are really required, they are ALWAYS required,,period!

And yes mount it on the bottom side SMD or trough hole dosent matter

as long as there is any.

>Since MBHP will never go into a professional production, where manual

>effort counts, I thought that this would be an adequate solution.

It has nothing to do with professional production or if its going

to be a home DIY, its completely irrelevant. Se above statement.

>But then I did some experiments with chained DINX4 and DOUTX4 modules

>and noticed no problems even without caps - also no "beta tester" reported

>problems - so I left them out from the schematics

>(my general worldly wisdom: so long nobody proves the converse, I don't believe it ;-

And boy, what you will fool your self by making that statement, im sorry Torsten

but that simply show your lack of experience by making that kind of statements.

You are an exellent software writer but you are "not" a hardware designer.

Not yet anyway!

>I learned in university that bypass caps are required to store and release

>energy on high current peaks.

Universityes today are miss leading the students, store and release energy

is for POWER applications, this is a HF to RF design, low current, fast rise

and fall times, over tones, resonance, impedance planes,bounching.

In uni you will only learn the thin surface, in real life it takes time to understand

things in depth, it takes years to become a quality engineer even the most trivial

tasks can if circumstances are right wreck a entire design, i have sen it,

i have even done it once! :-) No one is without faults!

Here is a  short story of life!

I and work mate once worked as test engineers, we did the final test

(burn in and compliance tests) for the first GSM base stations on the

market, (1990) we where quite stunned when in cabinet after cabinet,

every high speed DSP memory fused with a loud bang and flew around

inside the 2meters cabinets propelled by the rack fan blades!

We had to take cover! :-)

There was 3 memories for each DSP,  6 DSP's on each card,

12 cards in each rack, and 3 rack in every cabinet.(as far i  can recall it).

What was the cause to this extrodinary violence??

The software engineers had ignored the hardware engineers design note

and runned the DSPs memory busses to fast, the memories behaved

in that they clocked all right but because of the speed it vent over the

ICs power dissipation limit and fused/blow!

The software enginers lowered the memory access speed and

everything was fine!

I could tell you many more interesting stories what hapends

at the big corporations when one dont follow given design roules!

As the story when i was the hardware engineer and the assembly techican

ignored my design rules and turned the system fan units uppside down so

instead of wenting hot air out it pressed hot air into the cabinet!!....

And yes he lost his job later and i was a bit happier! :-) 

>Leaving out the caps can lead to EMI issue, e.g. short low-voltage bursts at

>neighboured gates which affect the functional behaviour, or emitted signal

>noise on analog circuits.

I think you mix EMI with RFI!

>That impedances resonance frequencies between the gates and wires can

>also play a role, was new to me it sounds disastrous, but I have to read

>some literature before I can give a statement on this.

It is disastrous, its a complex area to read about, still you wont get all the

ansvers by reading. Its about rise and fall times, impedance planes in PCB,

impedance and inductances in cabels, its really old stuff really.

>Are you sure that this is not an issue of HF logic and or high power designs only?

For some time now im been designing with the MSP430 MCU, its 8Mhz and

extreamly low power device, we are talking micro amp a full speed, still you

can get very strange behaviour if you do not decouple the device right, and

particularely if onedont decouple the internal 12 bit AD converter and its

reference. What tells this us? It tells us that "any design" of any speed or

power consumption can behave erratic due to bypass and power supply

issues.

For instance you have to bypass a "10khz Bw OP amp" properly otherwhise

it might become unstable, will ring, or even oscillate, it can state latch and

burn up, phase reverse, etc ,etc ,all at 10Khz!! Some of this dont even show

up in the data sheets!!

>Ok, I also have to say that at the beginning where I defined the MBHP

>my focus was on digital data processing, where signal noise doesn't

>hurt so much like on mixed signal designs, so long frequencies are relatively

>low (< 50 MHz) and the TTL levels are stable.

Once again, its not a matter of speed, its about rise and fall times of gates

switching around. For instance you can a have a 1Mhz CLK and 10nS rise

and fall times,,,,see!

>Using analog circuits (like the SID, AOUT, OPL3) was a new field which came

>later, and which was not taken into account from the beginning. Not sure how

>the MBHP would look today if it would be designed from scratch.

>As Duggle mentioned: it makes sense to consider such things on future designs.

Sorry but Duggle are on the wrong track!

Proper design starts at design start not after!

Just because that the project has been lucky so far is just because it

has been "lucky",nothing else. Tomorrow when the code might have

changed, you might have a errendous working MBHP.

There is a saying for that:

Why make something simple, when you can make it difficult!

Design by chance is not design, its chancing!

Its like saying:

-:, well i design this 68HC12 system( who draws 50mA) with a 10mA power supply!!

In the software industry its a well known fact that a code change can

make a produkt go completely bananas! Se my story about the DSP!

Why! Because the new code flipps the gate in a different pattern,

and that pattern migh be in resonance with PCB tracks, cabels,

drivers, etc.

Here is another example story!

I designed once a ASIC emulator using virtex FPGA's not one but

many in a large system, i turned bananas because i could not

callculate the power consumption of the system and therefore

designing the power supply become very problematic, the cause

was the ASIC engineers could not( or didnt want to tell, who knows)

estimate the FPGA's gate switching pattern sequence, and that tells

the system designer if the FPGA will draw copius with power or a

moderate amount.

>However, if somebody thinks that he can reduce jitter on the analog inputs

>or background noise on the SID by following this suggestion, then add

>10nF or 100nF caps at the \Vss/Vdd pins of each IC from the bottom +

>one 10 uF per module (or 100 uF for modules with high current consumption

>like mentioned above), but from my experience it won't solve the problems.

>Perhaps you will notice absolutely no difference - bypass caps cannot

>reduce glitches and spikes.

Why do you think engineers places 10-100nF ceramic or polyfim caps

between +pin at IC and gnd? For sheare fun? Because they like to waste

money?

>and they also don't help to eliminate ground loops and all those disturbing factors.

I havent said anything about ground loops, but now i will, ground lops depends

on (among many)power planes with varying impedance, this leads to potential

difference wich in turn leads to "current flows".

>Maybe I should also mention that I don't hear any additional noise frm the

> SID when all 99 LEDs of the control surface are toggled with different frequencies.

<Why? Because the SID power lines are wired starlike from the PSU. Seems that this

>was sufficient. However...

Exactly,you have learned something here by experience, you wired them star like

wich means that you have removed some of the impedance dependancies to a

"""lowimpedance"" summing juction at the power PCB.

Just because you tried a problem sugestion out of the skool book does'nt

mean that you actually understand what you did and what actuall happend

and thats the beauty of electronic design, to understand what you did

and what effect it had. And that takes years to learn.

>Karl, I must say that I'm happy about your posting. It's an important reminder

>(I swear that the next MBHP modules will be littered with bypass caps in future ;-)

>and contains some interesting informations about pot wiring, 4051 muxing, sockets too

At synth diy archives you can find a welth of info about decoupling, why

not use socketing , and impedances etc, also if you want to learn about

high speed (wich means rise and fall times) you ought to look at

Jack Gnassles web pages but most important read the book,

""Black magic of high speed design" this is a industry bible! Beware!

>Sidenote: the jitter monitor application from the MIOS download page

>demonstrates that caps against ground or shielded cables won't improve

>the signal quality here

I didnt talk about signal quailty, thats a completely different aspect,

im talking entierly about " system stability", you can have a stable

system but crap sound, and a unstable system with god sound.

I know, I have done both! :-)

Just because a system works dosent mean it works god!

Windows anywone!:-)

> maybe because of the reduced ADC resolution

>of 10bit. The jitter is normaly 1 bit, and this is caused by the 1/2 LSB error

>which can be found on any ADC. Sometimes I think that people are just too

>afraid that they are doing something wrong when they are "violating" such

>rules which are common in other design areas.

Just becuase it works on the PIC18F doesnt mean it will have the same

result in other MCUs, even a similare application with the same PIC18F

can give you very different results, you can even have different results

from different silicon batches from the same factory.

>This comment should not decrade your input!

Please everyone, understand this:

Im not trying to be nasty or the general wise guy, nor to tap you or

anyone down, i just point out a design error based on  20 years of

design experience. Im just trying to improve the MBHP design

for everyones happiness. If some folks feel embarrased or feeling

hurt, im sorry, but i cant do else!

Torsten you are a splendid software writer many more times

better then i will ever be, no question about that, but you and others

still have a lot to learn in hardware design. Im sorry to say but thats

the direction of the floating boat today! :-)

There is simply no short cuts to take!

Best regards and intentions.

KD

[Martin_Haverland]

wow.

alot to learn again...

studied physics and electrotechnics for 8 years...long time ago and most of it forgotten after working in computer and POS environments for nearly 10 years.

thank you for these clear words. impressing.

just what we all want. making it more stable.

thank you again

Martin

[jdutcher]

first of all, i'm relatively inexperienced here so i have no technical input.  i do, however, find it necessary to come to thorsten's defense.  KD, we all appreciate your input and i think everyone (thorsten included) will likely find it very useful.  and, as you said, you may have come off a bit harsh but you were just trying to help, and that's greatly appreciated.  however, to say that thorsten is "not a hardware designer" is unfair.  regardless of overall stability, thorsten's designs have lead to the creation of hundreds (thousands?) of well-functioning boxes.  i am enormously pleased with both the SID and SEQv2 boxes that i've built.  everything that thorsten has created is much more sophisticated than what most of us on this board would be able to create.  again, i know your only intention is to help in this case, but you also need to watch what you say.  you're right, he is a brilliant software designer.  but i'd argue that he is also a great hardware designer.  perhaps he wasn't able to catch some of the flaws that your 20+ years in engineering has allowed you to catch, but his designs work and they work well.  again, to call him "not a hardware designer" is simply untrue.  if thorsten was making any money from his hard work, i would be more concerned with any neglect of the problems that you have mentioned.  however, as it is, thorsten is doing this as a HOBBY and sharing his designs as a service to the community.  if he was a major hardware designer for a leading company or something, that would be another story, but he's not...so don't criticize him as one.

again, KD, let me make it clear that i appreciate your thoughts, i just think that you're not giving thorsten any credit for the hardware designs that have made so many people happy.

thanks,

james

[Martin_Haverland]

however, to say that thorsten is "not a hardware designer" is unfair.

search for "not a hardware designer" at this thread... you are not quoting correctely.

Torsten you are a splendid software writer many more times

better then i will ever be, no question about that, but you and others

still have a lot to learn in hardware design.

thats not quite the same isn't it.

i think we all "still have a lot to learn in hardware design".

learning is fun.

period

;)

[jdutcher]

And boy, what you will fool your self by making that statement, im sorry Torsten

but that simply show your lack of experience by making that kind of statements.

You are an exellent software writer but you are "not" a hardware designer.

martin, my quote is word for word.

listen, i agree that we all have much to learn.  i simply think that KD is giving thorsten absolutely zero credit for his hardware designs.  stable or not, thorsten's designs - software AND hardware - are the foundation of this community.  regardless of any errors, thorsten deserves more credit for his hardware work than KD seemed to give.  that was my complaint.  I cannot thank thorsten enough.  that said, i do find KD's comments to be valuable and I understand that his intentions were good.

thanks

james

[cheater]

Well, I do think KD used some harsh words towards Thorsten here. That's what sniffing rosin fumes does to you after 20 years ;)

KD: I'm familiar with synth-diy. This is NOT synth-diy. Behave :)

But only a fool looks at the way things are said, and not at the things that are said.

I suppose if KD didn't want to help us all he wouldn't have even replied.

Well, as I see the situation, it is:

1. KD proposed some changes and TK liked them

2. TK can't apply them because he doesn't own software good enough

3. KD owns software good enough

So, KD, if you want all of this done - diy dude! Really: a few boards won't take that much of your time.

If you want to help this project, and I guess you're the only one here with professional CAD software, DO send us some PCB designs :)

On a side-note: you seem pretty knowledgable with audio stuff. Perhaps take a look at the SID output stage to make it sound more phat? :) SmashTV mentioned something about matching output transistors to the SID...

idea: perhaps make two versions of some boards - one that'd be "cost-effective" without all the nice stuff and one that'd be "effective" with matched transistors, HI-FI grade capacitors for audio, extra circuits and whatnot...... that could let people get their hands on a working midibox fast, and it'd move the envelope higher in terms of what's possible - you could build a midibox to get working and uprgade it part by part to get the ULTIMATE sound :) In the end you get a pro-quality synth, but the fun starts much earlier than if you'd have to build it all at once.

[AndrewMartens]

I'm going to have to chime in here as well...

While we all love boards that are designed by professionals who get paid to do it 100% by-the-book, have labs full of test equipment, etc., that isn't always a reality for DIY projects.  If this was a commercial ready-made box that I was paying a bunch of money for (let's say the Sidstation), then I would expect it to have bypass caps / work 100% all the time / etc.  However, that's not what I'm going for.

What we have is a pretty good design that works well for most people most of the time.  Those who want extra features that were omitted (for whatever reason) in the existing design are free to add it in themselves.  The rest of us who are happy with something that works well enough, and just want to buy an inexpensive PCB of that circuit... well, we can.  If offered the choice of a professionally-designed PCB for $100, and a hobbyist-designed PCB for $10 that has a large community of people using it and helping troubleshoot problems, then I'm going to go for the latter.

Why?  Partly due to budget, and partly because the SID isn't exactly a crystal-clear chip anyways.  Part of the charm is getting some nasty noise along with it!  And if I don't like the noise, I can always tweak the design myself.

I think that TK has done a great job on all of the MBHP designs.  Perhaps he did make some incorrect design decisions along the way, but all hobbyists do.  Even a lot of professionals do - it's part of learning.  Sometimes one needs to omit features (and possibly reliability) to cut down on cost, which is understandable.  I support TK and hope that he continues to work on more cool designs in the future (with or without bypass caps  ;) )

[Martin_Haverland]

@jdutcher: thanks for correction. i was wrong. i searched with IE and didn't search with placeholders for the quotes in the quotes.

i should have known better, since i designed and maintained and used a helpdesk system for until 100 (upgradable) clients and an M$ based search engine for document management and a scalable database management all to be accessed really fast in a mixed slow ethernet / ras environement with realtime checking of access and security rules that was 99% self containing, web managable including databases and content management that was used for 6 years without flaws (until last year, and since now parts could not be supplemented) storing 100.000 cases of it and business problems so that a big german it trust was and is very interested in our work...since their international german speaking support is not nearly as fast and actual as we are...and we are their customers.

all based on IE... but obviously i make faults in simplest handling of IE and M$ search algos...tssss....

i'm really "no" IE or MS pro.  i was not working long and intensive enough on this... maybe your definition of "pro" is something else, that's ok so don't worry...

;)

i don't take this in any way as an offense to be corrected. i say thank you. you were right and i was definately wrong.

i will do better next time and say sorry.

@cheater: you are right. people are *SO* friendly at this board, that it's nearly examplaric in the net and diy scene (no *RTFM* kind of people...)

and it should be like that in future.

i want to say that KD just donored a very interesting MB extension design to us all to reduce noises with a very simple but cool analog circuit idea using just one pin of the mios system to drive an analog envelope following volume/noise reducer...

i think his spare time is much better invested in design of cool circuits for the community as in pcb optimizing.

(if you know, most pro's are working with pro software under nda, ok? but a nice try !!! ;D)

your additional circuits ideas are very nice, i was thinking about a cool little stereo opamp based mixer for our sids and fm's...

@matthew:

If this was a commercial ready-made box that I was paying a bunch of money for (let's say the Sidstation), then I would expect it to have bypass caps / work 100% all the time / etc.  However, that's not what I'm going for.

you don't want a synth that works 100% all the time?  ;D

my sid works / worked a little fluffy in my very overstreamed audio/midi environment and i would wish it to not to block that often as it did.

(even if i know the cure's and medicines / better midi routing...and yes i know, professional behavior was not a design goal but homestudio inspiration)

i would like it to behave a little more not *commercial* but even better if i can do it myself with little effort.

showing the customer complimented musicelectronics industries that diy is no "spleen" but a serious force with innovative quality ideas. 8)

make peace not war ;)

Martin

we all support TK.

if not, we wouldn't be here.

he is the anchorman of the whole midibox project and nobody wants to deny his importancy. not here and not at other diy sites.

[TK.]

Hi KD,

when I read your comments concerning my skills I come to the conclusion that for you hardware design is only related to the physical layer, means mainly PCB layout, circuit definition and component selection. This seems to be your area of expertise, and I'm happy that you are helping to improve and enhance this part of the project. This was never the work that I liked to do, for me it is just a job which need to be done to realize ideas. I was always very lucky once I got this part behind me as fast as possible (quick schematic, quick layout, without thinking that much about more adequate components or design rules) in order to start with the more enjoyable work.

I'm a little bit displeased about the general statement '"not" a hardware designer', but I know how to get it (I can live with such comments, and nobody needs to praise me or give credits before doing this). Maybe I should mention here in defence that I'm involved in hardware design for a big company in germany - but when I'm speaking about hardware here, I mean HDL design for system on chips (silicons). A completely different area, more abstract work, and I'm happy that this job has not that much to do with layout, electromacnetical effects or all that stuff which doesn't make fun - this is the area of other experts (the big advantage when working in a team).

For myself the purpose of programming software is just to stimulate the system. When you are amused about those software guys who are driving such a DSP patchwork out-of-spec, I'm lauging about the same guys who are not able to reach a better performance at lower speed and less power consumption + a higher reliability by understanding the relations in the system completely, programming adequate algorithms, defining and creating peripherals which relieve the CPUs. However, I also make such errors, but I'm doing the projects privately to improve my skills in such areas. Ok, so much about my personal focus.

Back to the topic: I think that you mainly want to make clear that the circuits have some room for improvements; this is understood and accepted. You are absolutely right when saying that we can run into trouble with the platform today if we don't take care about even such simple rules, and that some modules could especially not work properly anymore when they are not used in the same way like at the moment (e.g. once they are partly driven by a FPGA - the way I want to go in future).

These are also bad examples for people who are starting with electronic design and thinking (unreflected) "if TK is doing it in this way, it must be ok" (I whish this only for copycat companies who are cloning the designs ;-)

So, better to correct this "smoothly" in the next months than doing it later under pressure.

Am I right in the assumption that as "first aid" adding caps at the bottom of the PCBs (I'm asking the experts: are 10 nF better for future higher speed designs?), and 10 uF near to the power input (100 uF for the DOUTX4) are adequate enough for most modules? This would only cost me a little documentation effort.

Or is this no real help, since the routing of the power rails also has to be changed? (no further comment on this to hide my incompetence in this area)

Best Regards, Thorsten.

P.S.: long ago a wise man wrote: "Experience is something you don't get until just after you need it"...

[arumblack]

Hey KD, maybe yu can lend your expertise to some of my questions at this thread http://69.56.171.55/~midibox/forum/index.php?topic=3941.msg25566#msg25566 ? And if you know of a more capable/less crippled freeware pcb design software than eagle, chime in on it. Thank you much!

[smashtv]

It runs on a linear supply (no switch mode noise to battle), it uses HC class chips (near rail to rail operation enhances noise immunity exponentially vs. other logic families), I/O is properly debounced by MIOS, etc.

So what issue exactly are you wanting to fix here?  ;D

Throw a handful of ceramic caps at a Core+SID or FM, watch the noise floor rise drastically, and listen to the difference in sound with all of the new baby ground loops.....

My own testing of bypass vs. none did not show enough benefit to require them or add them to the designs, and with the SID (and probably other MB audio projects that share a ground with a Core) can hurt performance a bit. 

Please don't take my word for any of this though, believe what your scope shows you if you don't believe your ears.  ;)

Time for the pros to step up and prove the "needed" values, so I can pass some out, let everyone decide for themselves.

I could use a written spec for these new design requirements I need to follow with the needed changes......oh wait......explain to me again exactly what is -not working- like it is supposed to?

KD have ya built a box yet?

MIDIbox is proven.....Your turn.

Best

SmashTV

[KD]

>

>It runs on a linear supply (no switch mode noise to battle), it uses HC class chips (near rail to rail operation enhances noise immunity exponentially >vs. other logic families), I/O is properly debounced by MIOS, etc.

>So what issue exactly are you wanting to fix here?   ;D

The issue you dont understand! ;-)

>Throw a handful of ceramic caps at a Core+SID or FM, watch the noise floor rise drastically, and listen to the difference in sound with all of the new >baby ground loops.....

Why do you think "you" are having ground loops then!

First hint, its not the caps, its even described in previous mails , even Torsten has figured that out and you not!

Mail me when you have figured it out!

>My own testing of bypass vs. none did not show enough benefit to require them or add them to the designs, and with the SID (and probably other MB >audio projects that share a ground with a Core) can hurt performance a bit. 

>Please don't take my word for any of this though, believe what your scope shows you if you don't believe your ears.  ;)

Great, first making clever statements, then withdraw them, now thats a splendid

way  to make  lesser experience diy builders on this forum even futher confused!

>Time for the pros to step up and prove the "needed" values, so I can pass some out, let everyone decide for themselves.

Whos the pros and whos not?

>I could use a written spec for these new design requirements I need to follow with the needed changes......oh wait......explain to me again exactly >what is -not working- like it is supposed to?

>KD have ya built a box yet?

>MIDIbox is proven.....Your turn.

Are you afraid that you will "lose" sales on your PCB's,  smach TV?

Perhaps you should!!

KD

[KD]

Hi!

This has turned into a ridicoulus state,  i wont help you more on this matter, people are

focused on  how things are said not on whats said, and some goes futher to more or

less nitpicking on single sentences ripped out of its context or even single  words used.

And now some are even start to act smart asses on my behaf.

I simply dont have time for that anti bypass capacitor mumbojumbo talk,

If you dont want help, OK, so be it then!

For those who want to be of more knoweledge and not of lesser

knoweledge the rest can be happy to stay at moron state.

http://www.sigcon.com/Pubs/news/7_02.htm

http://www.sigcon.com/Pubs/edn/cleanpower.htm

http://www.edn.com/article/CA454638.html?industryid=2853

http://www.paktron.com/techarticles/hi_speed_circuit/high_speed.html

http://www.sigcon.com/Pubs/news/3_7.htm

http://www.sigcon.com/Pubs/straight/resonance.htm

http://www.altera.com/support/devices/power/integrity/pow-integrity.html

http://www.epanorama.net/wwwboard/messages/238.html

http://www.sigcon.com/pubsAlpha.htm

http://www.ganssle.com/articles.htm

http://www.seattlerobotics.org/encoder/jun97/basics.html

However there is much things the forum readers are not aware of, once a time (back in 98 or 99)

i sent Torsten a mail concerning the lack of bypass capacitors in mail concerning the

Core, PSU module, i recall he didnt answer then, so i asumed he had adjusted it since.

I also sent him some schematics on solutions wich he implemented and used,

that mail he replied to, no one on this forum nows this, even Torsten might have forgot

it and i dont mind, no credits was given at time for that either and really i dont give a

damn of the credits, because its purpose was of making the MPHB  cheaper and

better, so  before  people start to critizise me or other people out of the blue without

having decent background info i think its a god idea to chose your words,,,,,,,,,,, twice!

Regarding to some requests of some here if i have built a Mbox or two you can

figure that out by our self on what i said above..

I certanily dont have any spare time for any KD this, or KD that , if people are happy

to use the Torstens design as is,( without knowing possible and future errors), be happy,

use it, if you rather be pleased to be of lesser knoweledge, i couldent care less, and if

people dont want free help, just say so and i will go away.

Reg

KD

[smashtv]

Wow start a fight then run and leave cause you don't have time, good one.

I'll step up and say that while you might have a lot to offer this community, your attitude probably prohibits any reasonable dialog or contribution.

Please learn some manners, and come back when you are all grown up.  ;)

I guess I'm destined to be a moron, but at least I'm a happy moron without having to read anything else spewed by you.

The box works and you would rather burst into flames than prove an easy concept to me, we are done here.

A little hint about communication, be absolutely sure to spell a mans name correctly when you insult him, otherwise you run the risk of looking like an ass.....

if you rather be pleased to be of lesser knoweledge, i couldent care less,

Good thing!  you won't be hurt when I say

and if people dont want free help, just say so and i will go away.

Bye, "so", whatever.  Get lost so we can discuss this issue without getting beaten up by your "free help".

SmashTV

[KD]

>

>Wow start a fight then run and leave cause you don't have time, good one.

>I'll step up and say that while you might have a lot to offer this community, your attitude probably prohibits any reasonable dialog or contribution.

>Please learn some manners, and come back when you are all grown up.  ;)

>I guess I'm destined to be a moron, but at least I'm a happy moron without having to read anything else spewed by you.

>The box works and you would rather burst into flames than prove an easy concept to me, we are done here.

>A little hint about communication, be absolutely sure to spell a mans name correctly when you insult him,

>otherwise you run the risk of looking like an ass.....

Congratulations, you took the bait and swalowed it readily!

Reg

KD

[cheater]

SmashTV: man, you're childish. I expected more from you than to toss poop like monkeys do at other monkeys. Seriously - i think Thorsten can handle his problems on his own. He doesn't need support from others, he's not dumb or disabled. Starting flamewars like you have contributed to is the worst bane of all communities.

Let me explain KD's tone a bit. Most technical/diy communities work on the basis of knowledge, not community. People come and go, without being remembered, it's their ideas that count in the community. Thus, when someone is pretty knowledgable he's fully allowed to root out from the conversation people who don't really understand the topic. Because, after all, can they add anything to the conversation? No. If you want to take part, go and learn what's needed - and go back. This sounds harsh here, I know, but look at it this way: you're sitting in a university hall, a lecture is going on. You have missed the past 10 lectures and are asking the lecturer over and over what this-and-that means. Would you rather suggest everybody did that (thus making the lecture impossible) or would you rather suggest that people who don't understand the lecture go back to the books, and let the ones that DO understand PROFIT from the lecture? You can't expect people to teach you what you can read in the books. Nobody's going to lose all their time for teaching other people - we need some fruitful conversation here as well to get anywhere at all with the project. Thorsten won't go on with this stuff on his own forever you know.

KD: as you have seen, Thorsten, I and some other people have welcomed your contribution to our knowledge base. You must understand, though, that the customs of most DIY communities aren't known or aren't being applied here - so the tone that's completely normal in most mailing lists/news groups/forums that you take part in might seem harsh or offending here. Don't worry, this place is not idiot-ridden: if you ask someone (politely, please :) ) not to take part in a conversation, or if you suggest which topics they could read up on to understand the problem - they WILL do it. If they won't, we'll take care of them, don't you worry ;) But people here are kind enough to understand those things. You don't have to shoot people down at the first hit :) thus, your tone can be a bit more "rounded" and less "edgy" than in most boards - without fear of people bugging you all the time and making the conversations impossible and unfruitable.

[doc]

Oh.. Ohh.. it's gettin hot in the forum .... 8)

I had to read the whole thread twice, but still can't believe this !

Let's grab the facts:

- it's well known that we don't have bypass caps in the layouts  - RIGHT

- it's also well known that this doesn't matter till now - RIGHT

- I built a lot of  boxes , and if noise was a problem I took caps (...but it never was...). - RIGHT

- Most people don't need caps in their boxes - RIGHT

- if somebody has a modification - just post it and we use it ! - RIGHT

@KD:

- I'm sorry, if this was  told before, please be a little more polite with your words ! - It's not fun to read your comments !

- It's always easy to find something wrong -> don't critizise - change it. SO....... WHERE IS YOUR (ABSOLUTLY PROOFEN) LAYOUT ?

  means: if you know it better - thats fine - just give us a link where we can download the new EAGLE files.

  After doing this you'll earn our respect. Not before.

If you just want to join the community with your (unfair) comments please go and build some more GSM phones or what ever such an "expert" has to do.

We go on building our stupid midiboxes and having fun with them !  ;D

By the way: My mobile phone is more often damaged than my midibox.....

@SMASH

I think it's not worse to get angry on that comments. Just go on. You also do a good job ! (Ähm...I still do my layouts by myself... hope you won't kill me.. ;)

I think it's a kind of boring for me  to read useless things like RFI , EMI or other facts with three letters. Till now it don't gave us anything new for our boxes, or not ?

greets

DOC

(sorry for the bad english ...no native speaker ...)

[sjakie]

Yeah I agree. Keep it friendly, don't get all rude and personal. That serves no purpose at all. The first few posts were informative, after that a lot of irrelevant crap started flying around :)

I think for anyone trying to be 'professional',  ignoring crap politely or silently and remain focussed is always the best way to go ;)

Ofcourse what crap actually is, is totally subjective  ;D

[jdutcher]

SmashTV: man, you're childish. I expected more from you than to toss poop like monkeys do at other monkeys.

i disagree.  besides, isn't it just as bad (not to mention rude) to badmouth SmashTV like that?

Seriously - i think Thorsten can handle his problems on his own. He doesn't need support from others, he's not dumb or disabled.

that's not the point.  i, for one, think very highly of thorsten, which is why i came to his defense...not because i thought he needed help.

Starting flamewars like you have contributed to is the worst bane of all communities.

talk to KD about this one, cheater.  KD said, "Congratulations, you took the bait and swalowed it readily!"  sounds to me like he's been enjoying this.  while your info on typical forum etiquette was news to me (thanks for the info, though), i'm not really sure it justifies KD's attitude.  as far as i'm concerned, there's a difference between discussing information in "business-like" manner and mixing that information with explicit insults and condescension.

oh well...this'll all blow over soon enough, i guess...

[arumblack]

I certanily dont have any spare time for any KD this, or KD that , if people are happy

to use the Torstens design as is,( without knowing possible and future errors), be happy,

use it, if you rather be pleased to be of lesser knoweledge, i couldent care less, and if

people dont want free help, just say so and i will go away.

Reg

KD

Sorry your so busy........ Hmmm it just seemed like maybe you wanted to help out.

I just don't understand, you claim to offer free help, but don't have time to help anyone?

I will check out the links you posted, Thank you.

There are people here who want to understand theese things, and there are people here who just want to build a box and make music. I think most would fall into the latter category. For them I think, "If it ain't broke , don't fix it" applies.

I have studied electronics for just over a year, and none of my classes have yet touched on ground loops, and only briefly mentioned bypass capacitors in digital circuits to deal with switching noise. Anything else I have to learn for myself, and have benifited greatly from discussions in this and other forums, possibly more than reading it for myself.

Anyway, sorry to rant on,

Thanks again for the links,

AB