The difference and an end to digital sound introduction. Next posts on sampling theorem.

Here's a very crude analogy to explain the difference between analog and digital sound, a vinyl records walls generate an analog signal by moving the stylus left and right as well as up and down its diagonally moved for stereo, but just imagine for a moment that it's just left and right a record directly. That's the analog signal via the motion of the stylus.

But a digital Sound Source is instead sort of like a virtual stylist riding in a virtual Groove. The sound samples are snapshots in time of where the stylist was a DAC will then create an analog signal by running a virtual stylist through this virtual Groove and placing it at exactly the correct location and thus generating the appropriate voltage level as defined by the samples by using a giant list of numbers to recreate sound instead of the Local properties of a plastic disc the sound can be reproduced flawlessly and accurately with no Reliance on the record players cartridge properties. The Integrity of its stylus. It's motor the quality of the vinyl Etc.

The biggest Boon of digital sound was that it eliminated all of the little nuances that might change how a recording sounds digital sound is in a sense absolute but getting digital sound into the hands of the average consumer took a long. It's the amount of raw data generated by sound recording was immense for the standards of the time although 650 megabytes. The data equivalent of the first compact discs is a paltry sum of data in the 21st century.

                                          

It was unimaginably huge in the early 1970s when the first commercial digital sound recording took place for context the Commodore 64released the same year as the compact disc has 64 kilobytes of RAM and that was considered huge for the time a compact disc held Roughly 10,000 times as much data 64 kilobytes of cd-quality audio lasts this long that's not super helpful.

We will continue to look at the methods that were used to store data from digital recordings and we'll discuss the rise of the compact disc as a robust consumer friendly format for digital sound reproduction and distribution.

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From copper to PCB [Part 6] – Design Rules

Now as we have said about routing tracks, we have to understand that this track placing or  routes and via have rules that is the manufacture can only make them physically in a certain way we cannot draw and demand something which is lets say very small and very close placing of copper tracks or components as you have to understand there are physical machines, etching solutions, copper depositors which will work at some point of time on your designed PCB and they have some very real physical and practical limitations which are inevitable.

So, we cannot place copper tracks too close, we cannot place components too close, we cannot make via too close or close to a drill point. We cannot drill too close and so on. Also due to this there are auto routers which help in taking this DRC in account and the software or the algorithm or the computer as we see can just place or draw the tracks all by itself and there is just no need to worry about breaking rules and creating huge trouble.

So in this way our PCB design gets completed. I know this is not a very detailed explanation but it is something or the series is something that can at least give you a rough idea about what is happening.

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From copper to PCB [Part 5] – getting more Physical

So for now we have only discussed about how the two layers are, but depending on the use case, there can be more than two layers and in that case the manufacturers have more copper sand witches sand witched and through our given GERBER information, what diagrams are to drawn on sides are conveyed and all are drawn independently and then sand witched.

Now I have said there are files which convey information, so I have a point to add that these all assembly are done in parts and only the diagram part and drill parts are done with the help of drill machines and photo developers and oxidation and copper deposits etc.

Now as we sort of now know how the PCB is manufactured lets start where we left off, that is after logical diagram and attaching footprints.

So, after all those we just have to draw circuits and those are just how copper tracks will go where the components will be placed, where the power lines will be where the ground planes will be and so on. Also first we just have to place components in place as we want and they are connected with the help of raster nets which are derived from the logical diagram actually, and these raster nets are then to be made copper tracks that is how physically copper will run from one component to another and how the ground planes would be. These running of copper tracks is called routing and has some specific rules.

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From copper to PCB [Part 4] - Intro to Physical View

So, after we have done logical schematic diagram with footprints attached we can now just start drawing on the PCB using our softwares Physical layout editor or a board designer, here what we draw initially is on the top surface of the PCB.

                          

Ok so as I have said surface and we are into physical view now so lets describe how physically the PCB is prepared in the real world in fabrication centre. So, in fabrication centre they start with something called a copper sandwich, which is copper layers on either side with a dielectric material between them, the dielectric material is what the whole PCB gets support on and the top and bottom sides are copper so all the electrical diagrams and contacts and contact pads and via are done on them using first marking with help of UV and then etching.

                                        

                                              

                               

So, first the raw material as described is taken and then the diagrams from the customer are taken and transferred on the copper layers as per given formats. Now for this transfer there is no specific PCB design file, but as we might have heard of we have something called as GERBER files which are files which are generated from the PCB design software and have all the information about how the board drawings would be and how the silkscreen that is all the writings and diagrams would be and how the copper pads will be exposed after the solder mask and a NCDRILL file which tells where the mechanical boundaries are and how the holes are to be drilled.

                                

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From copper to PCB [Part 3] - more than Logical View : Footprints

                                     

So, after we have the logical diagram and most accurately correct diagram, we have to attach footprints to them, that is what component will look like what when placed on a physical design. As this is something we will touch and feel in real life, so the PCB design process has two divisions, one the logical circuit design and other the physical design, both are equally important and the physical design depends on the logical design.

                                     

These footprints I am talking of are provided by manufacturers itself and some by PCB manufacturers also, and after we make logical diagrams we have to attach them or in some softwares they are automatically attached for general non-conflicting components.  The footprints are the white coloured markings we see for most PCBs, which is just below the components are placed.

                                      

In some cases we might have to attach special parts like a heat sink or a some display whose exterior part is not given in footprint in that case we can manually add a symbol also or do it during physical design process.

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viewing digital sound using VEGAS

See on a graph Zoom way way way in on the waveform and eventually you can see the individual samples themselves.

And that's all digital sound is it's a huge list of numbers strung together in order to get these numbers back into sound we can hear we need to use the opposite of an analog to digital converter or attic. So we'll use a DAC or digital to analog converter. I like it when names makes sense a DAC will read the string of numbers and generate an analog voltage based upon their values the DAC will smooth out. Out the choppiness of Apple's a bit to make the resulting sound a little more natural and now you've got an analog signal to send into an amplifier and drive a loudspeaker. The result is a near perfect reproduction of the originally recorded sound.

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PCB Components Photographs by Amrita [SmartPhone]

These are some photographs taken by Amrita Adhikari,

Theme : Technology - Printed Circuit Boards (PCB) Components -  SmartPhone, Inside Consumer Electronics.

Internal Flash Storage of SmartPhone Micromax Q380

Mediatek System on Chip[MT6582] next to the ROM of Micromax Q380

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Component Closeup 01 by Subhankar[close to an open web cam sensor]

Photo by : Subhankar Karmakar

Theme : Technology - IC Components - Web Cam, Inside Consumer Electronics.

Image of a web camera sensor taken with another web cam with close focus

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PCB Components Photographs by Amrita [FeaturePhone]

These are some photographs taken by Amrita Adhikari,

Theme : Technology - Printed Circuit Boards (PCB) Components - FeaturePhone, Inside Consumer Electronics.

Main SoC of a Featured Phone(ikal)

Main SoC of a Featured Phone(ikal)

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