View Full Version : Electronics design

08-01-2006, 05:13 AM

This posting isn's as technical as the ones generally posted here. My question is, for an aspiring inventor like myself, how does one go from circuit and code design to consumer electronics product?

Is deciding which ICs to use an informed decision mainly based on experience? How does the circuit get transformed into PCB design? Again, does optimization come from experience? How does one learn how to pair a PCB and its components with a case, such as an injection molded case? What comes first? Designing the case or designing the PCB? How do you analyze the effects of transmission line interference? What software is available to facilitate these processes? Are there libraries of commonly used ICs and parts? (I don't think a HDL program or Spice variant is what we're looking for...?) What books are available? What courses are available? (This coming from a computer engineering graduate). Is this the area of study known as Design for Manufacture and Assembly? (Saw a course like that). Any other tips, pointers, suggestions, advice?

The question developed as I was looking at an iPod which is an engineering marvel, then a laptop, then realizing how intricately planned my 12 dollar desktop atomic alarm clock is. How do they do this?!?

Thanks, Shmuel

P.S. As a final question, how to know when to use an FPGA or similar versus dedicated ICs? As you can tell, I don't have a lot of practical experience even with my CoE degree.

08-01-2006, 05:50 AM
These points generally work together...

1)Yes. all of the components that are used are used for specific reasons. Generally, an EE will look at the requirements of the project and find out what is needed for a) functionality and b)requires less resources and c)What meets electrical specifications. A lot of people choose their ic's based on size and shape, if it is a small consumer electronics project

2)Another Yes to experience. PCB's can be either hand-made, or fabricated at board houses. The way those designs come about is by an engineer creating a board layout in programs such as OrCad, Protel, WinQCad, or Eagle. There are applications such as "ExpressPCB" in which you can design a layout, and they will create the boards for you...The only problem is that they use their own files and you can't do production runs.

What I generally do once I get my clients specifications is create a schematic, and then layout the schematic into a pcb program. This pcb program should output your PCB layout into a gerber file (GBX). This file is a universal file that any board manufacturer can use. I then send those Gerber files to the board manufacturer, they make the boards and ship them back.

Board manufacturers tend not to do any error checking. They will make what you give them...so if there is a design flaw, it is up to you to resolve it.

From that point, you need to populate the board with the components. You can do this yourself, or hire a manufacturing house to do it. There are all-in-one locations that will do PCB manufacturing and Component Population, and assemble the cases, and even box them up for you ready for the truck...it just depends on how much money you want to invest.

A good resource to find these locations is www.alibaba.com (http://www.alibaba.com). They have everything from component suppliers to manufacturers, to marketers to distribution channels, and import/export.

3) Usually, the size of the case dictates the size of the circuit board...but it can be the other way around. If you are making a handheld device, then you need to make the casing first (allow space for PCB mounts) and then say, "OK...The pcb MUST have these dimensions...). At that point, you look at your schematic...and you find the components that will work to fit onto the circuit board.

If size is not critical...go ahead and make the circuit board first (put in mounting holes) and then decide how you want the casing to look.

Generally, these two items (electronics and manufacturing) are entire projects in themselves. Taking them both on will be VERY difficult and VERY time consuming. Find somebody who is good at what you are not, and get some help.

4)Again...It depends on what is most important to you. IF size and looks are most important, you will have to build the case first, but leave room for change if the PCB cannot meet your size specifications. If Function is most important...Build the board first, then build the case around it.

5)Having reliable test equipment is crucial for any PCB/Circuit Designer. Since the Board and circuit need to be tested anyways, it is very valuable to have an Oscilloscope, a logic analyzer (If you can get one), and a Spectrum Analyzer (if you can get one)

6)The suite I use is WinQCad. It provides the following: Schematic layout, Parts development (for creating libraries), PCB Layout, Footprint development, AutoRoute, Handroute, and print.

Once you have the schematic designed (you may have to make some of your own parts or import them from Protel), you save the netlist. The PCB layout imports that netlist. You place your components on the board where you need them. If you want, you can autoroute the traces (this application does VERY well) or you can hand route the traces. Make sure you add text or any changes, along with mounting holes. Then you can print up the .pdf files, and create gerber files for production houses.

7) Yes, there are. Unfortunately, different applications have different amounts of libraries. You can buy libraries on line, and some are free. Remember...SOMEBODY had to develop these parts, so it depends on what you get...I have had no problems making my own libraries, and I feel very confident in the pin connections because I put them there.

8)A book that really helped me get a grip on things is "Building your own PCB". I got it at Barnes/Noble...or borders or something like that. They usually have an electronics section

9)Most Community Colleges have courses available for electronics understanding. As far as PCB Development, it is an art...so you can learn one way to do it...but everybody does it a little bit different.

10) That course is more for the mechanical design...It may have something about circuit boards, but probably not too much.

11)If your background is business...let an EE go ahead and do the design work for you. It will cost you some money, but you will get it done much faster, and it will be correct. I am a contract Electrical Engineer. I know that my weakness lays in mechanical design...so I stick to the Electrical engineering and let somebody who understands everything else do everything else.

A lot of product builders make a huge mistake in trying to do everything themselves. While they are taking 3 years to learn everything and understand what is going on, their product has been developed by a team of 3 people in 4 weeks.

I do a lot of work for others. I have developed for XBox360, designed amusements, museum displays, and Laser show equipment. The people I work for generally have a good understanding of what is going on, but I am usually able to make things smaller, cheaper, and with more functionality than they originally intended and that is exciting.

I would suggest finding a team with a business/marketing person, a Mechanical Engineer, and an Electrical Engineer...They don't have to share in your glory...but they do accept money for their time. Most people on this site do it as a hobby and would love to help out...without wanting their names on the box.

Good luck...releasing a project is a huge undertaking...And please don't try to think you can do it on your own...If you want it on the shelves...you need people who are really good at what they do...otherwise, you will be wasting your time...like I have in other projects.

Post Edited (Steel) : 7/31/2006 10:55:14 PM GMT