Author Topic: EEVBlog #407 - Mailbag  (Read 29961 times)

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Offline bitwelder

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Re: EEVBlog #407 - Mailbag
« Reply #50 on: January 13, 2013, 10:47:56 am »
I'm working on the next 2.. One is on the SPI bus the other one on PCB design.
PCB design will have everything + the kitchen sink. i have almost 20 pages on just defining the board contour ... There is so much involved in even this simple task that it boggles your mind.. i keep handwritten notes and there's not a day that goes by without having to jot down ' i need to explain that as well'.
Hmm... any idea how thick is the PCB design book going to be?  :D

It will certainly deserve a Mailbag Special episode from Dave, but let's wait patiently for now.

 

Offline free_electron

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Re: EEVBlog #407 - Mailbag
« Reply #51 on: January 13, 2013, 03:16:31 pm »
The book will indeed start from scratch. The goal is to give you a good base to start with. Too many people jump in making a board without thinking. The thinking part aside thereis also the knowing part.

I haven't seen too many people asking to evaluate their board before sending it off on this forum, but I have seen tons on the other forum. And it's invariably the same.

  • Where are the mounting holes ?
  • Why is the power transistor in the middle and not at the edge  where you can slap a heatsink on ?
  • How come the input of the amplifier is directly next to the output ... Wanna make an oscillator ?
  • How come all traces have the same thickness ?
  • What's with all the jumper wires ?
  • Why is you board 99% empty space and 3 miles of cabling... You can rotate parts you know ?
  • If you are going to saw or cut this board .. Don't you think this trace is a bit too close to the edge ?
  • I see you are using the default footprints.... The pads on that to220 are so small because they are intended for a thru plated board. Make this single sided and the thermal stress will pop them off the board...
And so on ...

That's what is going to be covered. Here is a bunch of things to think about before we even launch the cad tool.... When you got that figured out , start the cad program and define a board mechanically . Once that looks good lets place some parts now ... Partition the design. Tackle different strategies for high voltage, analog , digital, high speed , precision ,  once mechanical placement ( mechanical placement is the stuff that must have a determined location: switches, connectors, displays, leds, mounting holes, heatsinks, the case etc ) then rough placement is done ( rough placement is the big boys like big fat chips, you don't touch resistors and caps , unless they are big bulky caps and power resistors ) and after that you can begin thinking about getting a power distribution grid in place.... Pull in decoupling, filtering etc.  The last problem then is all the other crap.... And then maybe we can start drawing a connection...

There is a reason a layout is called artwork. Before you hit the chisel on that block of marble you need to have a good idea what you want the final work to look like. Or you may find out the block is too small to include the head ...
« Last Edit: January 14, 2013, 01:55:40 am by free_electron »
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Offline cwalex

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Re: EEVBlog #407 - Mailbag
« Reply #52 on: January 13, 2013, 04:22:51 pm »
The book will indeed start from scratch. The goal is to give you a good base to start with. Too many people jump in making a board without thinking. The thinking part aside thereis also the knowing part.

I haven't seen too many people asking to evaluate their board before sending it off o. This forum, but I have seen tons on the other forum. And it's i variable the same.
Where are the mounting holes ? Why is the power transistor in the middle and not at the edge  where you can slap a heatsink on ? How come the input of the amplifier is directly next to the output ? Wanna make an oscillator ?
How come all traces have the same thickness ?
What's with all the jumper wires ?
Why is you board 99% empty space and 3 miles of cabling... You can rotate parts you know ?
If you are going to saw or cut this board .. Don't you think this trace is a bit too close to the edge ?
I see you are using the default footprints.... The pads on that to220 are so small because they are intende for a thru plated board. Make this single sided and the thermal stress will pop them off the board...

And so on ...

That's what is going to be covered. Here.is a bunch of things to think about before we even launch the cad tool.... When you got that figured out , start the cad program and define a board mechanically . Once that looks good lets place some parts now ... Partition the design. Tackle different strategies for high voltage, analog , digital, high speed , precision ,  once mechanical placement ( mechanical placement is the stuff that must have a determined location. switches, connectors, displays, leds , mounting holes, heatsinks , the case etc ) then rough placement is done ( rough placement is the big boys like big fat chips, you don't touch resistors and caps , unless they are big bulky caps and power resistors ) and after that you can begin thinking about getting a power distribution grid in place.... Pull in decoupling, filtering etc.  the last problem then is all the other crap.... And then maybe we can start drawing a connection...

There is a reason a layout is called artwork. Before you hit the chisel on that block of marble you need to have a good idea what you want the final work to look like. Or you may find out the block is too small to include the head ...

I always make double sided boards and have them made by itead but I always struggle with parts placement for the best layout between components. I have only made very simple circuits and still struggle! It feels like there would be some rules you could follow to make that part easier and better. It would be awesome if you could cover this concept in your book. But like I said I will buy it regardless! Thanks for your response and all your informative posts in general.

I think I'll post my next design and get input before committing the design for manufacture.
 

Offline free_electron

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Re: EEVBlog #407 - Mailbag
« Reply #53 on: January 14, 2013, 02:09:29 am »
That is the goal of this book. There is a bit of base knowledge you need to be aware off. And the rest is a bunch of strategies.
Placement strategies, power strategies , routing strategies.

The idea is to create a kind of 'cookbook' . Need this done ? do that .. but ... be aware of ...  and so on.
I got a project worked out as an example. I will make a gizmo ( you'll be able to buy the board and actually build it ) that covers all kinds of 'gotcha's. The project is a USB audio Amplifier with some kick behind it... ( 4x 40 watts ). So i can cover placement wise :

- mecha locks ( power amplifier stage + heatsink + thermal reliefs + mechanical stress relief )
- big and bulky ( big fat caps in the power section )
- precision stuff ( The USB DAc is has awesome S/N )
- all kinds of ESD and EMC trickery ( there will be a metal shield over the USB section )

Routing wise it's also versatile.
There's high speed clocks, user interface ( play/pause/ volume controls /next previous track+ display + cpu )
There's precision analog ( analog audio channels , microphone input )
there's low power amp ( headphone output )
there's 'power' in the endstage
there's pulse loads ( endstage is a MOSFET amp stage that has embedded boostpump to deliver serious 'bass boom' )
there's controlled impedance ( USB 2.0 ) and EMC ESD strategies on the computer interface . ( the amp has a USB hub built in as well. you get 2 spare USB plugs. the reason for the hub is that this is a composite device having the CODEC on USB as well as the CPU on usb. ( so you can display track name etc on display )

and a bunch of other things ...  The idea is to have a project that has a case example of any possible 'gotcha'. the board will be designed to fit in an off-the shelf heatsinked metal enclosure and have a nice illuminated volume knob and some angled pushbuttons ( again to teach how to build this kind of stuff on a pcb ) the pcb will be mounted screwless in the case and have the necessary cutouts and specialties .. anyway ... you'll get to see it as it progresses.
i expect to have a prototype of the pcb somewher emid of the year. i got the schematics roughly done and i'm working step by step through the PCB layout and making screencaptures as i go.

That is the hard bit about writing a book. you start writing something and halfway the section you realise ... crap. i need to talk about this as well , go modify the board , make new screencaptures.  and there's always stuff you forget and you have to go back and redo it a few weeks later..

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Online mariush

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Re: EEVBlog #407 - Mailbag
« Reply #54 on: January 14, 2013, 03:20:58 am »
free_electron, your posts made me seriously consider this book and your previous one, Mastering i2c

I was checking Amazon UK and this one is sold through Amazon UK by Elektor at 26 uk pounds, but they refuse to accept sending it to Romania.

On the other hand, the Mastering I2C book is sold by Elektor but fulfilled by Amazon UK and that one works to order and ship, at 22 uk pounds even.

Kind of annoying, because both books are 29.5 uk pounds on the Elektor website. I'm not even motivated to create an account and see if that includes VAT or not and how much they'd charge me in shipping (later edit: checked, 7 pounds.. on amazon uk it's about 3 pounds).

Anyway, probably nothing you can do about it, but it just goes to show how annoying it can be when publishers make random restrictions.

ps. Just realized I might sound cheap, but with the prices on Amazon, both books would have fit my budget. Can't afford to get both at 60 pounds plus whatever shipping right now.
« Last Edit: January 14, 2013, 03:27:57 am by mariush »
 

Offline cwalex

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Re: EEVBlog #407 - Mailbag
« Reply #55 on: January 14, 2013, 03:24:29 am »
That is the goal of this book. There is a bit of base knowledge you need to be aware off. And the rest is a bunch of strategies.
Placement strategies, power strategies , routing strategies.

The idea is to create a kind of 'cookbook' . Need this done ? do that .. but ... be aware of ...  and so on.
I got a project worked out as an example. I will make a gizmo ( you'll be able to buy the board and actually build it ) that covers all kinds of 'gotcha's. The project is a USB audio Amplifier with some kick behind it... ( 4x 40 watts ). So i can cover placement wise :

- mecha locks ( power amplifier stage + heatsink + thermal reliefs + mechanical stress relief )
- big and bulky ( big fat caps in the power section )
- precision stuff ( The USB DAc is has awesome S/N )
- all kinds of ESD and EMC trickery ( there will be a metal shield over the USB section )

Routing wise it's also versatile.
There's high speed clocks, user interface ( play/pause/ volume controls /next previous track+ display + cpu )
There's precision analog ( analog audio channels , microphone input )
there's low power amp ( headphone output )
there's 'power' in the endstage
there's pulse loads ( endstage is a MOSFET amp stage that has embedded boostpump to deliver serious 'bass boom' )
there's controlled impedance ( USB 2.0 ) and EMC ESD strategies on the computer interface . ( the amp has a USB hub built in as well. you get 2 spare USB plugs. the reason for the hub is that this is a composite device having the CODEC on USB as well as the CPU on usb. ( so you can display track name etc on display )

and a bunch of other things ...  The idea is to have a project that has a case example of any possible 'gotcha'. the board will be designed to fit in an off-the shelf heatsinked metal enclosure and have a nice illuminated volume knob and some angled pushbuttons ( again to teach how to build this kind of stuff on a pcb ) the pcb will be mounted screwless in the case and have the necessary cutouts and specialties .. anyway ... you'll get to see it as it progresses.
i expect to have a prototype of the pcb somewher emid of the year. i got the schematics roughly done and i'm working step by step through the PCB layout and making screencaptures as i go.

That is the hard bit about writing a book. you start writing something and halfway the section you realise ... crap. i need to talk about this as well , go modify the board , make new screencaptures.  and there's always stuff you forget and you have to go back and redo it a few weeks later..

OMG  ^-^ I think you will sell a LOT of this book!

I wonder if it would be a good idea to have a section where you guide someone through getting the board done to the gerber level and advice to send the files to be manufactured so that someone can get experience with their hand held to get a board manufactured and then build the project on that board. I know I was really nervous when making gerbers and getting them done, felt like I was walking around in the dark even with all the good advice in forums and research I did.

Turned out that itead were good with communication of what I did wrong in my gerbers and even offered to fix it if I sent them my project file when I was continually sending them gerbers in a way they didn't like  :palm:

I got there in the end without resorting to send the project files but still a book like yours would have made me feel much more confident. It's a shame that you can't do it as a guide for a particular EDA package, would limit your audience too much but really I think that is only a small downside. The book will still be awesome and with list of content you just described I'm getting excited about it's release  ;D

EDIT: I forgot to mention I would be prepared to pay up to a couple hundred AUD$ for this book with accompanying projects included. Do you think it will come in under that? or is it too soon to give approx pricing?
« Last Edit: January 14, 2013, 03:29:05 am by cwalex »
 

Offline free_electron

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Re: EEVBlog #407 - Mailbag
« Reply #56 on: January 14, 2013, 04:21:45 am »

I wonder if it would be a good idea to have a section where you guide someone through getting the board done to the gerber level and advice to send the files to be manufactured so that

But of course ! that's elementary my dear watson. Gerber generation and its gotcha's is in there as well. including verifying of the Gerber. Ditto for ODB++ and some other advanced stuff ( i'm not going to give away all the stuff here :) ). that includes doing realy crazy shit like V-scores , route and retain , mousebites , panelisation, sub-boards , flex , castellations , slotted holes, plated and non plated holes , using drill tables and manipulating them for special purposes ( like allocating specific drill sizes to make slits post plating etc )

The sample project board will probably be a 4 layer ( so i can demonstrate controlled impedance .. can't really do that on 2 layers).
Attention will be given on layer stack building , prepreg selection not only for dielectric constant but also for warpage, hygroscope, altitude and high frequency )

Other sections including creating project output ( assembly drawings , pick and place data , documentation drawings ) and handoff to manufacturing. After all a board design is only finished if it is mass producable by monkeys. As a board designer you need to hand off all data required for your backend. it does not stop at the generation of the gerber.  there is pastemask generation for example. knowing how to scale pads , how to inject lattices , how to deal with non populates, project variants , pullback and much much more ...

The step where you create gerber is only like the 75% point for a board design. there is still work to do afterwards before you can consider the pcb design 'complete' a pcb design is the translation of an electric schematic into a CAD dataset that will be used to build an ASSEMBLED board ( it doesn't stop at a bare board ) that FITS in its intended enclosure and is robust against ESD and passes EMC...

« Last Edit: January 14, 2013, 04:25:05 am by free_electron »
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Offline cwalex

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Re: EEVBlog #407 - Mailbag
« Reply #57 on: January 14, 2013, 05:13:26 am »

I wonder if it would be a good idea to have a section where you guide someone through getting the board done to the gerber level and advice to send the files to be manufactured so that

But of course ! that's elementary my dear watson. Gerber generation and its gotcha's is in there as well. including verifying of the Gerber. Ditto for ODB++ and some other advanced stuff ( i'm not going to give away all the stuff here :) ). that includes doing realy crazy shit like V-scores , route and retain , mousebites , panelisation, sub-boards , flex , castellations , slotted holes, plated and non plated holes , using drill tables and manipulating them for special purposes ( like allocating specific drill sizes to make slits post plating etc )

The sample project board will probably be a 4 layer ( so i can demonstrate controlled impedance .. can't really do that on 2 layers).
Attention will be given on layer stack building , prepreg selection not only for dielectric constant but also for warpage, hygroscope, altitude and high frequency )

Other sections including creating project output ( assembly drawings , pick and place data , documentation drawings ) and handoff to manufacturing. After all a board design is only finished if it is mass producable by monkeys. As a board designer you need to hand off all data required for your backend. it does not stop at the generation of the gerber.  there is pastemask generation for example. knowing how to scale pads , how to inject lattices , how to deal with non populates, project variants , pullback and much much more ...

The step where you create gerber is only like the 75% point for a board design. there is still work to do afterwards before you can consider the pcb design 'complete' a pcb design is the translation of an electric schematic into a CAD dataset that will be used to build an ASSEMBLED board ( it doesn't stop at a bare board ) that FITS in its intended enclosure and is robust against ESD and passes EMC...

I repeat... OMG! OMG!

Eagerly awaiting!!!!!!

Thanks for the updates :)
 

Offline EEVblog

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Re: EEVBlog #407 - Mailbag
« Reply #58 on: January 14, 2013, 05:31:02 am »
That is the goal of this book. There is a bit of base knowledge you need to be aware off. And the rest is a bunch of strategies.
Placement strategies, power strategies , routing strategies.
The idea is to create a kind of 'cookbook' . Need this done ? do that .. but ... be aware of ...  and so on.

Well, I guess there goes my PCB book idea I've had for many years. Now I don't have to write it  :phew:

Dave.
 

Offline free_electron

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Re: EEVBlog #407 - Mailbag
« Reply #59 on: January 14, 2013, 05:36:24 am »
That is the goal of this book. There is a bit of base knowledge you need to be aware off. And the rest is a bunch of strategies.
Placement strategies, power strategies , routing strategies.
The idea is to create a kind of 'cookbook' . Need this done ? do that .. but ... be aware of ...  and so on.

Well, I guess there goes my PCB book idea I've had for many years. Now I don't have to write it  :phew:

Dave.

wanna be proofreader ?
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Offline cwalex

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Re: EEVBlog #407 - Mailbag
« Reply #60 on: January 14, 2013, 05:48:29 am »
That is the goal of this book. There is a bit of base knowledge you need to be aware off. And the rest is a bunch of strategies.
Placement strategies, power strategies , routing strategies.
The idea is to create a kind of 'cookbook' . Need this done ? do that .. but ... be aware of ...  and so on.

Well, I guess there goes my PCB book idea I've had for many years. Now I don't have to write it  :phew:

Dave.

wanna be proofreader ?

I know you were asking dave but my hand is up for being a proofreader. My experience wouldn't help much with technical content though.  :-DD
 

Offline EEVblog

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Re: EEVBlog #407 - Mailbag
« Reply #61 on: January 14, 2013, 06:07:54 am »
wanna be proofreader ?

Nice try, but I ain't falling for it! ;D
(just as hard as writing the thing!)

Dave.
 

Offline ErikI

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Re: EEVBlog #407 - Mailbag
« Reply #62 on: January 18, 2013, 09:14:20 pm »
I also bought the book after seeing it in the video. I'm teaching a course about designing and manufacturing electronics and after a quick scan I would like to include it as one of the suggested materials for the course, if you don't mind. It gives a very nice overview of the topics I'm covering in the course and I'm also considering ordering some more for the students. Keep up the good work.  :-+
 

Online mariush

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Re: EEVBlog #407 - Mailbag
« Reply #63 on: January 18, 2013, 09:32:43 pm »
Well, after writing my previous post here, I sent an email to elektor's order email with some questions.

It's 3 or 4 working days later, i still got no answer. I guess it's the typical dutch way, they probably were in some holiday.
 

Offline IanB

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Re: EEVBlog #407 - Mailbag
« Reply #64 on: January 18, 2013, 10:43:50 pm »
About PDF versions of books, one pattern I have seen is that you buy and register a physical copy of the book, you get a key to download a personal PDF version.

In some sense, this relies on human nature: if I have paid for the book, I am not inclined to give away the PDF for free to other people (why should they get for free what I have paid for?). Another point is that the PDF file says "Licensed to (name)" on the title page, so it makes clear where it came from.

This ultimately is a commercial decision: you will sell more copies by making the book more useful, vs some amount of sharing among people (who may not have bought it anyway). Many people like me will buy the hard copy if available because paper books are easier to read and last forever.
I'm not an EE--what am I doing here?
 

Offline MikeK

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Re: EEVBlog #407 - Mailbag
« Reply #65 on: January 19, 2013, 01:56:41 am »
wanna be proofreader ?

Nice try, but I ain't falling for it! ;D
(just as hard as writing the thing!)

Yep.  I made this mistake, once.  Guy was translating his Dutch book into English and I proofread and corrected it.  Thirty years ago this was called "co-writing", but I got a shitty little mention in the foreward.
 

Offline amyk

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Re: EEVBlog #407 - Mailbag
« Reply #66 on: January 19, 2013, 10:01:46 am »
In some sense, this relies on human nature: if I have paid for the book, I am not inclined to give away the PDF for free to other people (why should they get for free what I have paid for?). Another point is that the PDF file says "Licensed to (name)" on the title page, so it makes clear where it came from.
That's probably a valid assumption in individualistic cultures (most of the West) but not in collectivist ones (most of Asia) which value sharing more. In that case identifying who shared it won't discourage, since that's viewed not as "he/she is the guilty one" but "he/she is the one to thank"! It has changed somewhat in China now due to the western influence but this explains a lot of what they do that the west disapproves of.
 


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