Author Topic: EE electroic engineer designer basics please  (Read 15633 times)

markphaser

EE electroic engineer designer basics please
« on: November 19, 2006, 12:28:40 AM »
What are some basic EE or electroic engineer designer basics please

1.) Seperate the power supply from other boards
     so if the power supply components short or open u can easily replace
      it with another wall wart easier to troubleshoot when its seperated

2.) Don't mix power supply voltages for digital components and analog components
     they should be seperated power supply lines
     (can cause ticking or switching off/on sounds bleeding into the analog signals)
    The digital components should be "isolated" from the analog components for
    power supply voltages

3.) What components that are really close together can use noise or create
      oscillation sounds when to close together like stray capacitance?
     Because when doing the schematic of the board your going to make in
     electronic workbench or some type of software it will do tracemaking
     for the boards thats sent to the CNC machine shop to press the boards
     When making putting the components/parts and soldering to the boards
      when made sometimes if components/parts are to close together can
      create oscillations or noises in the real world that u didn't know when proto
      typing it on a breadboard or simulating it in software it didn't happen but
      when u make the real board with components solder to it causes oscillation
      and noises from certain components/parts to close together
 
      Which components/parts when close together would cause oscillations or
      noises please?

Shielding:
4.) When making a prototype on a breadboard of the circuit for a R&D department
     how do u shield the circuit?
      When making the board in real life there is mostly a shielding problem
     what are some basic EE shielding tricks to do in general for basic digital and
      analog circuits?

5.) EE engineers focus on Shielding and ground loops
     What are some basic EE ground loop trick to do in general for basic digital and
     analog circuits?

6.) What others do u guys know about please that can add to my list?

but what do most digital test technicians do ?

What kind of waveform analysis for digital test technicians do ? with truth tables,data sheets(for digital components), pulse train charts

pulse train charts are like 16 or more parallel square or PWM waveforms
and u have to find the time interval offset or phase shift

How would i know if the clock signals are all synced up?

markphaser

Re: EE electroic engineer designer basics please
« Reply #1 on: November 19, 2006, 05:56:33 PM »
List 10 things a EE designer must know when making a prototype and PCB boards?

Sir H C

Re: EE electroic engineer designer basics please
« Reply #2 on: November 19, 2006, 09:33:12 PM »
You do not need separate digital/analog supplies if you are not doing much switching.  Only when you have clocks and even then you might not worry if the clock is so high that it is out of band for the analog stuff.

1. Separating the power supply is added cost.  The reason to separate the supply to a wall wart is UL.  If you don't plug directly into the wall, you don't have to do that UL stuff, just buy approved AC adaptors.

2. Isolation is good, but again cost, if you don't need to separate things, don't.  Over engineering can lose in the market place as your costs are higher than the other guy's.

3. Inductors are the worst as they create big fields that could go through other loops of wire.  Other than that, just separate wires of vastly different gains, and decouple decouple decouple.

4.  For this read some of the great articles from Linear Tech, or the article by Paul Brokaw of Analog Devices.  These guys have lived this stuff longer than most anyone.

5.  Don't make ground loops that is the secret.

6. have good flow on the board.  If the board is not flowing then you are hosed.

7. aesthetics do count.  If something looks ugly usually it is.

8. The slew of other questions are way too application specific to give a generalized answer.  It is like asking how do you remove the gall bladder of some animal and not naming the animal.

this is for the edification of others.

KerryF

Re: EE electroic engineer designer basics please
« Reply #3 on: November 19, 2006, 09:49:06 PM »
I shield things on the board and under the board with the insulation from wires I have stripped.  I usually save all of my stripped insulation, so I have a lot to use.

Heres an example (I didnt clean up my board yet):


Heres a few questions...
1. I know its good to clean the bottom of the board's solder joints after you finish to clean off excess flux, but what if it gets to the components?  Can it damage them?
2. What about water, can it damage parts to dip them in water?

R.G.

Re: EE electroic engineer designer basics please
« Reply #4 on: November 19, 2006, 10:54:34 PM »
Quote
List 10 things a EE designer must know when making a prototype and PCB boards?

1. When to stop.

The others are all trivial compared to that one.
R.G.

Quick IQ Test: If anyone in a governmental position suspected that YOU had top-secret information on YOUR computer, how many minutes would you remain outside a jail cell?

markphaser

Re: EE electroic engineer designer basics please
« Reply #5 on: November 19, 2006, 11:06:00 PM »
Thanks alot Sir HC for the help

what is good to Isolate or what is some basic engineering component to component isolation to know about please?

Capacitors,inductors,transformers should not be close together right? or close to op-amp input pins or transitors input pins
can amplify noise or oscillations right?


Sir H C

Re: EE electroic engineer designer basics please
« Reply #6 on: November 19, 2006, 11:11:40 PM »
These two are the bomb:

http://www.analog.com/UploadedFiles/Application_Notes/135208865AN-202.pdf

http://www.mit.edu/~6.331/an47fa.pdf

These two guys bring more to the table than all the Red Lobsters combined.

markphaser

Re: EE electroic engineer designer basics please
« Reply #7 on: November 19, 2006, 11:25:32 PM »
 Sir H C y did u pick those 2 pdf files are they about EE designer they seem to be about decoupling only

Sir HC did u go to EE school? what kind of pdf files are good for EE designers for this type of subject we are talking about
to add on to the list . Like if one of us went on a R&D job interview and they said list 20 things that a EE designer should know
about what would u guys list please?

Ground loops,isolations,seperations etc. what else please?

 

Sir H C

Re: EE electroic engineer designer basics please
« Reply #8 on: November 19, 2006, 11:50:10 PM »
Did you even look at the two files?  One is on decoupling.  That is huge in PCB design.

The other is on high speed PCB design.  Everything about isolation, and the rest.

All your questions are answered there.  That is why I chose those two articles.

For the twenty things, buy the book by Jim Williams "The Art and Science of Analog Circuit Design".  There is a great quiz for the prospective student there.  But before you get an interview, you have to get the degree.  VERY few people without an EE degree get design positions in industry.  Ground Loops, Isolation, and that crap would be very far down the list, those are secondary and tertiary issues, you have to know C=I dv/dt before those. 

Read those two papers, *understand* those two papers.  Those two guys are great writers and very clear in what they say.  They cover all you asked.

call1800ksmyazz-
Usually water is not a problem.  Old carbon-comp resistors and some old germanium transistors might have moisture issues, but most modern parts are designed to be washed when they are made.  One technique was to put PCBs in the dish washer and run it.  I don't recommend that, but some water or rubbing alcohol shouldn't be too detrimental to the board.  The problem with flux is usually that it can become conductive with moisture and then that starts messing with your circuit.

markphaser

Re: EE electroic engineer designer basics please
« Reply #9 on: November 20, 2006, 12:07:10 AM »
Thanks Sir HC for the help and information

I went to amazon to look for EE designer books which ones should i get or which ones did any of u guys have when u guys took your EE courses to know about EE designing for R&D

Yes decoupling is going for digital chips,clocks,switching,LFO ticking, thats all i can think of what else is decoupling for?

R&D designer:
basic EE designer should know:
1.) Decoupling
2.) Isolation of components to other components, traces are to close, magnetic fields to close,
        a.) Not good isolation can cause oscillation frequency,ringing,noise, interference
3.) ground loops
4.) shielding- for interferences
5.) ? anything else please?

R&D designer math:
1.) Calculating the input and output impedances and wattage values for resistors
2.) using fourier transform math,fourier series math,laplace transform math
3.) What else do R&D EE designers use math formulas for please?


Sir H C

Re: EE electroic engineer designer basics please
« Reply #10 on: November 20, 2006, 07:08:54 AM »
Paul Brokaw is an analog design engineer working for ANALOG DEVICES.  His decoupling deals with analog circuits.

Math formulas:

I=C dv/dt
V=L di/dt
Ic = Is * exp(Vbe/Vt) + 1
Id = const * (Vgs - Vth)^2 (or some other number)

And a ton more. 


markphaser

Re: EE electroic engineer designer basics please
« Reply #11 on: November 20, 2006, 03:09:11 PM »
Those are the "rate of change" formulas for current and voltage through a cap or inductor

Sir H C

Re: EE electroic engineer designer basics please
« Reply #12 on: November 20, 2006, 03:37:53 PM »
Those are the "rate of change" formulas for current and voltage through a cap or inductor

the first two, then the bipolar and mos equations.

johngreene

Re: EE electroic engineer designer basics please
« Reply #13 on: November 20, 2006, 04:08:05 PM »
Quote
List 10 things a EE designer must know when making a prototype and PCB boards?

1. When to stop.

The others are all trivial compared to that one.

+1
I started out with nothing... I still have most of it.

Seljer

Re: EE electroic engineer designer basics please
« Reply #14 on: November 20, 2006, 04:12:34 PM »
I shield things on the board and under the board with the insulation from wires I have stripped.  I usually save all of my stripped insulation, so I have a lot to use.


thats not really sheilding, thats just the rubber insulation making sure you don't accidently short out anything, sheilding would be an actual outer conductor which is connected to ground, surrounding the wire thats carrying the signal (shielded cable or coaxial cable), preventing noise and other things from messing with your signal

markphaser

Re: EE electroic engineer designer basics please
« Reply #15 on: November 20, 2006, 04:54:16 PM »
Seljer is right

Sir H C why would EE designers need to know the rate of change of current going in and out of the cap,inducator,transistor,op-amp,mosfet,fet,tube? what information are they going to use or do with this information from knowing the rate of change or
"transconductance" of input/output and through the component?


puretube

Re: EE electroic engineer designer basics please
« Reply #16 on: November 20, 2006, 05:18:47 PM »
they will receive calls for a job-offer.

(seriously!)

mojotron

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Re: EE electroic engineer designer basics please
« Reply #17 on: November 20, 2006, 05:47:02 PM »
Quote
List 10 things a EE designer must know when making a prototype and PCB boards?

1. When to stop.

The others are all trivial compared to that one.

+1

I would say:
1) when to start and what the progression of developing an idea is
- In real engineering situations, I have seen more good-ideas/projects fail due to a poor understanding of when you are finished with design and ready to simulate and prototype. Any efficient design effort is going to have a progression of:

idea <-> head-scratching/thought <-> initial design <-> simulation -> prototype -> finish (PCB/writeup...)

If you don't jump steps in that process, generally you can finish what you start - if it was do-able in the first place. Once you have a good simulation (of which paper simulation works too) of the idea, a prototype effort would not involve debugging (a major time-sink) except for trivial stuff. Debugging a design is a strong indicator that an engineer needs to look at how they are doing things rather than the design itself.

- Also, if you have all of the design/prototype work done, the time spent on making a PCB layout is minimal and efficient.

2) When to stop...

johngreene

Re: EE electroic engineer designer basics please
« Reply #18 on: November 20, 2006, 06:40:02 PM »
Quote
List 10 things a EE designer must know when making a prototype and PCB boards?

1. When to stop.

The others are all trivial compared to that one.

+1

I would say:
1) when to start and what the progression of developing an idea is
- In real engineering situations, I have seen more good-ideas/projects fail due to a poor understanding of when you are finished with design and ready to simulate and prototype. Any efficient design effort is going to have a progression of:

idea <-> head-scratching/thought <-> initial design <-> simulation -> prototype -> finish (PCB/writeup...)

If you don't jump steps in that process, generally you can finish what you start - if it was do-able in the first place. Once you have a good simulation (of which paper simulation works too) of the idea, a prototype effort would not involve debugging (a major time-sink) except for trivial stuff. Debugging a design is a strong indicator that an engineer needs to look at how they are doing things rather than the design itself.

- Also, if you have all of the design/prototype work done, the time spent on making a PCB layout is minimal and efficient.

2) When to stop...
But you need to define 'done'. :)

What I see over and over again, is engineers (we are talking about electronic engineering here and not hobby enthusiast) are always thinking about the design and as it progresses, and test data is collected, they come up with better ways of doing it. Continuously. So it is the common problem of wanting to make the design 'perfect' which is a never-ending process. So, an engineer that is capable of meeting milestones knows when the design is 'good enough' to satisfy the requirements and resist the temptation to make it even better when in the end, it will never be noticed.

It has nothing to do with debugging, it is all about knowing when to stop designing.

--john
I started out with nothing... I still have most of it.

markphaser

Re: EE electroic engineer designer basics please
« Reply #19 on: November 20, 2006, 06:43:45 PM »
thermal design problems/issues:
 Its common to have a product come back afters its been sent out PCB and certain components resistors or IC op-amps or transitors that are causes to much heat burning the board what would cause this problems please? to much current or the part is not the right rating for wattage? or op-amp ,transitors voltage rating problem?

PROTECTION circuits in power supplys,op-amps,transistors should have protection diodes for the inputs,outputs,power,ground pins so if any surge of current it protects the IC pins or components

I re-phrased my question

What are 10 to 20 EE electronic designer "issues" or "common problems"?

I need to know the most common designer issues and common problems in general or basics for any PCB boards or circuits please?