Math and electrical desgin

[Rick C]

On Saturday, March 28, 2020 at 6:08:43 PM UTC-4, Joerg wrote:

On 2020-03-28 13:38, blocher@columbus.rr.com wrote:
On Friday, March 27, 2020 at 6:00:10 PM UTC-4, Rick C wrote:

[...]


So your work is not so much circuit design as it is system design?

I like to think I straddle circuits and systems. I am decent at both
but certainly not an expert at analog. The problem in my company is
that there is not enough work in circuit design to keep one always
busy. I also think that most circuit problems are better solved
through a system approach. If you get the system concept wrong, then
the circuit is going to be wrong. If you know what you want at the
high level, it is easier to tell if your circuit design is adequate.


Amen!

Top-down is generally the only approach that really works. Now we'll
have to explain that to the next generations. All the ones who have
served in the military don't need to be told, they know this already.

There are very few times when a pure top down approach is used. Then even when it is used that's only because the bottom portions are very, very similar to something you've already completed.

It is seldom a design project is just pure design. There are almost always questions near the bottom that can only be resolved by bottom up design for at least that portion.

One thing that bottom up design does is to make testing easier. When people talk about top down design they usually really mean top down decomposition and bottom up design.

--

Rick C.

-- Get 1,000 miles of free Supercharging
-- Tesla referral code - https://ts.la/richard11209

 

[Joerg]

On 2020-03-28 13:38, blocher@columbus.rr.com wrote:
> On Friday, March 27, 2020 at 6:00:10 PM UTC-4, Rick C wrote:

[...]

So your work is not so much circuit design as it is system design?

I like to think I straddle circuits and systems. I am decent at both
but certainly not an expert at analog. The problem in my company is
that there is not enough work in circuit design to keep one always
busy. I also think that most circuit problems are better solved
through a system approach. If you get the system concept wrong, then
the circuit is going to be wrong. If you know what you want at the
high level, it is easier to tell if your circuit design is adequate.

Amen!

Top-down is generally the only approach that really works. Now we'll
have to explain that to the next generations. All the ones who have
served in the military don't need to be told, they know this already.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Roger_the_Dodger]

The further on you get with electronics/software the more maths you tend to need. Ohms law is pretty basic maths. AC theory is a little more challenging.
Kirchoffs theory relies on simultaneous equations.

In software I wrote a PCB design program which was mostly elementary geometry.

For a USB oscilloscope I designed I had to get into signal processing.
I had to use a Fast Fourier Transform for displaying a frequency graph.

 

[Joerg]

On 2020-03-28 13:34, blocher@columbus.rr.com wrote:

On Saturday, March 28, 2020 at 4:23:14 PM UTC-4, Joerg wrote:
On 2020-03-27 12:29, blocher@columbus.rr.com wrote:

[...]

My chosen area is more RF/radio engineering. On the radio side,
the signal processing stuff is definitely math intensive and
required to be good at it.


Sorry, but I don't really agree and RF is my home turf. I learned a
lot more from ham radio than in all the course at the university
and not a lot of math was involved.


Notice how I said RF/radio. It is the radio part - modulation that
requires the math stuff.

Sure, most of us aren't in the business of pure science where you
generate an RF signal just to be used in experiments and such. We
generally design RF solutions that fulfill the purpose of messaging and
control. So there is always going to be some kind of modulation and
nowadays lots of digital communications.

... About ten years ago I realized that I could
not really call myself a radio engineer if I did not have the basics
of DSP down.

Oh, you can. I know only little about DSP though I do prescribe coding
strategies to DSP engineers. In fact, I might some day leave this earth
without ever having programmed a DSP.

... Most of the radio - except power amplifiers/antennas and
LNAs is getting done in DSP. It is a tough mountain to climb, but I
just could not shake the idea that I could not call myself a radio
engineer (in today's world---professionally) if I did not understand
DSP.

There is a lot more tools to understand this stuff than there was 15
years ago, and things like gnu radio are quite amazing.

And then the next problem, how do you be a player in radio - DSP - if
you are not good at software (I am not - but I do want to learn the
gnu radio cadence of programming).

Well, I am player in radio and I really suck at software

What I found, especially over the last 20 years, is that younger
engineers no longer truly understand the fundamentals of RF. With truly
I mean gut feel, instinct and all. How RF propagates, how it mixes when
you don't want it to, how it leaks into places it shouldn't, and so on.
Just to give you an example:

In my younger years I was often tasked with the design or re-design or
medical Doppler ultrasound systems. The main reasons why I was called in
were that prior solutions were too noisy, had inadequate dynamic range
or simply were too expensive. Even in the late 80's this was already
highly processor-driven. So you have DSP programmers. However, they knew
nothing about anything that was in front of the ADCs. That was my turf.
Pulse train generators, mixers, filters with gliding frequency response
over time domain, quite complicated stuff. So we had an almost perfect
split, I did the analog parts, they did the signal processing. Of
course, we communicated a lot.

This hasn't changed much except that I have largely left the field of
med-tech. Now it's more industrial, consumer, oil/gas and aerospace. I
am an advocate of doing anything in the digital domain that can be done
there if cost and power consumption remain reasonable. However, I do not
consider it a problem to hand off all the coding to someone else, just
like I do that with micro controller based projects.

[...]

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Phil Hobbs]

On 2020-03-28 17:01, jlarkin@highlandsniptechnology.com wrote:

On Sat, 28 Mar 2020 13:06:24 -0700 (PDT), George Herold
ggherold@gmail.com> wrote:

On Friday, March 27, 2020 at 6:25:46 PM UTC-4, pcdh...@gmail.com wrote:
How important is mathematics to you as an engineer?
Do you consider yourself an applied mathematician?
I would say that I do.  As an analog designer how much do you
use various mathematical concepts.

A lot of what I do is (a) for a given electro-optical design concept, calculate how good it _could_ be, (b) figure out how to get there, and (c) if that's a win, proceed, but if not, think up something better and goto(a).

Significant amounts of math are required to get a good result, as well as a lot of lore and old fashioned crank-turning.

My favorite type of math is 'back of the envelope' calculations.
Those are fun... but it is always better with one or two other
people. (you can sorta check each other..)

George H.

Cheers

Phil Hobbs

We play a game, in a meeting, of doing the math in our heads. To
slide-rule sort of accuracy, not many digits, but close enough to see
what matters.

We've got pretty good at it, so we can really impress visitors.

Yup. That's part of the way I maintain ascendency over various
whippersnappers.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Clifford Heath]

On 29/3/20 7:23 am, Joerg wrote:

On 2020-03-27 12:29, blocher@columbus.rr.com wrote:
A topic to elicit some thoughts....
How important is mathematics to you as an engineer?
It ranks surprisingly low on the pecking order.
 ...  Do you consider yourself an applied mathematician? ...
Definitely not. My sister (has a mathematics degree) is razzing me about
that all the time but that's just how I am. IMO engineering is mostly
instinct. People who don't have them can't be good engineers. Instinct
comes with practice, lots of practice.

By definition, anything that only comes with practice is *not* instinct.

I think you mean intuition. Intuition comes with practice. It's just a
cognitive habit, and habits come with practice.

      ... Theoretical EMAG is important, but you can go a long
way without being super proficient at maxwells equations.
True ... but ... one must have a very good gut feel of how Maxwell
applies to stuff. Otherwise the whole design could turn into a nightmare
at the EMC lab.

Students are taught to think of electrons flowing inside wires. Is it
any wonder they have trouble with RF, where they have to visualise
everything as a field, with wires to guide the field?

Clifford Heath

 

[Phil Allison]

Clifford Heath wrote:

-----------------------
Flyguy wrote:

...when math is needed there is no substitute. Try explaining complex impedance to someone w/o math; it just won't make any sense. Or how a capacitor can conduct current. Or how a transformer works. Or how RF signal transmission works. Had a discussion once with an FAA person on why radar can pick up non-metallic objects like birds - it pretty much ended when I mentioned "dielectric constant." It really becomes indispensable when you start designing control systems or advanced signal analysis.


That's because you aren't very good at explaining things.

** Massive false asumption.

Feynman used
to say that anything he couldn't explain to an undergraduate in ten
minutes was something he didn't actually understand.

** Physics undergrads already know a whole lot of math and Feynman would certainly have used actual math and math concepts in his explanations.

So your quoting him is absurd.

I have successfully explained all the things in your examples to
complete science-illiterates. It's possible, but you need to find the
right entry point.

** Really??

A wise man once said " everything in science has an easily understood explanation - only problem being, that explanation is not true.



....... Phil

 

[Phil Hobbs]

On 2020-03-28 16:23, Joerg wrote:

On 2020-03-27 12:29, blocher@columbus.rr.com wrote:
A topic to elicit some thoughts....

How important is mathematics to you as an engineer?


It ranks surprisingly low on the pecking order.


 ...  Do you consider yourself an applied mathematician? ...


Definitely not. My sister (has a mathematics degree) is razzing me about
that all the time but that's just how I am. IMO engineering is mostly
instinct. People who don't have them can't be good engineers. Instinct
comes with practice, lots of practice.

Instinct is super useful for generating ideas. We come up with some
scheme by instinct, but then test it by math. The math involved is
super familiar--what's the noise floor, the bandwidth, the settling
time, and so on. It's the familiarity that makes that seem like it's
the same as design instinct, but it isn't.

Cheers

Phil Hobbs

(Who does a lot of math because he's fortunate enough to do a lot of
stuff where the instinct hasn't developed yet)


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

On Sat, 28 Mar 2020 14:22:12 -0700 (PDT), Flyguy <tomseim2g@gmail.com>
wrote:

On Saturday, March 28, 2020 at 2:01:15 PM UTC-7, jla...@highlandsniptechnology.com wrote:
On Sat, 28 Mar 2020 13:06:24 -0700 (PDT), George Herold
ggherold@gmail.com> wrote:

On Friday, March 27, 2020 at 6:25:46 PM UTC-4, pcdh...@gmail.com wrote:
How important is mathematics to you as an engineer?  
Do you consider yourself an applied mathematician?  
I would say that I do.  As an analog designer how much do you
use various mathematical concepts.

A lot of what I do is (a) for a given electro-optical design concept, calculate how good it _could_ be, (b) figure out how to get there, and (c) if that's a win, proceed, but if not, think up something better and goto(a).

Significant amounts of math are required to get a good result, as well as a lot of lore and old fashioned crank-turning.

My favorite type of math is 'back of the envelope' calculations.
Those are fun... but it is always better with one or two other
people. (you can sorta check each other..)

George H.

Cheers

Phil Hobbs

We play a game, in a meeting, of doing the math in our heads. To
slide-rule sort of accuracy, not many digits, but close enough to see
what matters.

We've got pretty good at it, so we can really impress visitors.



--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"

Personally, it was vital. Not all the time, but when math is needed there is no substitute. Try explaining complex impedance to someone w/o math; it just won't make any sense.

I think I could do that, purely visually with no math.

>Or how a capacitor can conduct current. Or how a transformer works.

Those can be explained pretty well without math.

Or how RF signal transmission works. Had a discussion once with an FAA person on why radar can pick up non-metallic objects like birds - it pretty much ended when I mentioned "dielectric constant." It really becomes indispensable when you start designing control systems or advanced signal analysis.

--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"

 

On Sun, 29 Mar 2020 09:39:04 +1100, Clifford Heath
<no.spam@please.net> wrote:

On 29/3/20 8:22 am, Flyguy wrote:
...when math is needed there is no substitute. Try explaining complex impedance to someone w/o math; it just won't make any sense. Or how a capacitor can conduct current. Or how a transformer works. Or how RF signal transmission works. Had a discussion once with an FAA person on why radar can pick up non-metallic objects like birds - it pretty much ended when I mentioned "dielectric constant." It really becomes indispensable when you start designing control systems or advanced signal analysis.

That's because you aren't very good at explaining things. Feynman used
to say that anything he couldn't explain to an undergraduate in ten
minutes was something he didn't actually understand.

He also said that he had to visualize something before he could start
to apply equations to it. Einstein said similar things: visualize a
concept first.



--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"

 

On Sat, 28 Mar 2020 15:00:02 -0700 (PDT), Roger_the_Dodger
<cresswellavenue@talktalk.net> wrote:

The further on you get with electronics/software the more maths you tend to need. Ohms law is pretty basic maths. AC theory is a little more challenging.
Kirchoffs theory relies on simultaneous equations.

I haven't solved a simultaneous equation or used matrix math since I
was forced to do that in college.

I did once take an integral, about 25 years ago, to compute a mosfet
dynamic power dissipation, but I already knew the answer well enough
from simple arithmetic. Spice would have been more accurate than
either.

In software I wrote a PCB design program which was mostly elementary geometry.

For a USB oscilloscope I designed I had to get into signal processing.
I had to use a Fast Fourier Transform for displaying a frequency graph.

Did you program the FFT yourself from first principles, or did you
look up the code somewhere?



--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"

 

On Sat, 28 Mar 2020 18:43:22 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-03-28 17:01, jlarkin@highlandsniptechnology.com wrote:
On Sat, 28 Mar 2020 13:06:24 -0700 (PDT), George Herold
ggherold@gmail.com> wrote:

On Friday, March 27, 2020 at 6:25:46 PM UTC-4, pcdh...@gmail.com wrote:
How important is mathematics to you as an engineer?
Do you consider yourself an applied mathematician?
I would say that I do.  As an analog designer how much do you
use various mathematical concepts.

A lot of what I do is (a) for a given electro-optical design concept, calculate how good it _could_ be, (b) figure out how to get there, and (c) if that's a win, proceed, but if not, think up something better and goto(a).

Significant amounts of math are required to get a good result, as well as a lot of lore and old fashioned crank-turning.

My favorite type of math is 'back of the envelope' calculations.
Those are fun... but it is always better with one or two other
people. (you can sorta check each other..)

George H.

Cheers

Phil Hobbs

We play a game, in a meeting, of doing the math in our heads. To
slide-rule sort of accuracy, not many digits, but close enough to see
what matters.

We've got pretty good at it, so we can really impress visitors.



Yup. That's part of the way I maintain ascendency over various
whippersnappers.

Cheers

Phil Hobbs

They are so impressed and stunned that they don't check our numbers.



--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"

 

[Rick C]

On Saturday, March 28, 2020 at 6:26:55 PM UTC-4, Joerg wrote:

On 2020-03-28 15:19, Rick C wrote:
On Saturday, March 28, 2020 at 6:08:43 PM UTC-4, Joerg wrote:
On 2020-03-28 13:38, blocher@columbus.rr.com wrote:
On Friday, March 27, 2020 at 6:00:10 PM UTC-4, Rick C wrote:

[...]


So your work is not so much circuit design as it is system
design?

I like to think I straddle circuits and systems. I am decent at
both but certainly not an expert at analog. The problem in my
company is that there is not enough work in circuit design to
keep one always busy. I also think that most circuit problems
are better solved through a system approach. If you get the
system concept wrong, then the circuit is going to be wrong. If
you know what you want at the high level, it is easier to tell if
your circuit design is adequate.


Amen!

Top-down is generally the only approach that really works. Now
we'll have to explain that to the next generations. All the ones
who have served in the military don't need to be told, they know
this already.

There are very few times when a pure top down approach is used.


In medical and aerospace all the time. Has to be that way, else you can
land in hot water with the Federales. Without a top-down approach it is
hard to maintain a proper design history file set.

Especially in such large projects it is nearly impossible to use a 100% top down approach. There are too many unknowns. It is very common to design a portion of a large design, construct and test it before continuing with the integration. This is common with such components as engines in the space program.

... Then
even when it is used that's only because the bottom portions are
very, very similar to something you've already completed.

It is seldom a design project is just pure design. There are almost
always questions near the bottom that can only be resolved by bottom
up design for at least that portion.

One thing that bottom up design does is to make testing easier. When
people talk about top down design they usually really mean top down
decomposition and bottom up design.


My projects typically start at the system spec level. That gets drilled
into and sub-projects are parceled out. That way the documentation is
always first and will be fleshed further out during the design. Not as
an afterthought like it unfortunately is with many others.

Yes, I didn't say top down is never used. I simply said it is not always used 100% and is not always the best way. It is very common to separate out a portion of a design and investigate that portion before designing it into the whole. There is no point in trying to design the system surrounding and depending on a component if there are questions about the component that can only be resolved by further design or even construction and test of that component.

I don't expect this conversation to get anywhere with you. We have disagreed on things many times you often refuse to even try to understand what I say. Your reply this time doesn't offer any promise of a change to that pattern.

--

Rick C.

-+ Get 1,000 miles of free Supercharging
-+ Tesla referral code - https://ts.la/richard11209

 

[Clifford Heath]

On 29/3/20 10:00 am, jlarkin@highlandsniptechnology.com wrote:

On Sat, 28 Mar 2020 15:00:02 -0700 (PDT), Roger_the_Dodger
cresswellavenue@talktalk.net> wrote:
For a USB oscilloscope I designed I had to get into signal processing.
I had to use a Fast Fourier Transform for displaying a frequency graph.

Did you program the FFT yourself from first principles, or did you
look up the code somewhere?

A Discrete Fourier Transform is easy to program from first principles,
as soon as you know what it actually is. FFT not so much, but having
done a DFT at least gives you the intuition about how an FFT is possible.

 

[Rick C]

On Saturday, March 28, 2020 at 7:32:47 PM UTC-4, Clifford Heath wrote:

On 29/3/20 10:00 am, jlarkin@highlandsniptechnology.com wrote:
On Sat, 28 Mar 2020 15:00:02 -0700 (PDT), Roger_the_Dodger
cresswellavenue@talktalk.net> wrote:
For a USB oscilloscope I designed I had to get into signal processing.
I had to use a Fast Fourier Transform for displaying a frequency graph..

Did you program the FFT yourself from first principles, or did you
look up the code somewhere?

A Discrete Fourier Transform is easy to program from first principles,
as soon as you know what it actually is. FFT not so much, but having
done a DFT at least gives you the intuition about how an FFT is possible.

An FFT is not so hard. You just have to get your head wrapped around the permutations. I can't imaging being the guy who first came up with it. Likely recognized something in the sequence of sines related to something else in math he was familiar with. That's what the FFT is about, decomposing the DFT sines into operations that can be shared among all the harmonics.

Don't recall the name, but I think this was before it was very useful given the state of computing, so I don't know that the guy was looking for a way to speed up the DFT. I suppose a wikipedia search would answer that question.

--

Rick C.

+- Get 1,000 miles of free Supercharging
+- Tesla referral code - https://ts.la/richard11209

 

[Rick C]

On Saturday, March 28, 2020 at 7:43:37 PM UTC-4, Rick C wrote:

On Saturday, March 28, 2020 at 7:32:47 PM UTC-4, Clifford Heath wrote:
On 29/3/20 10:00 am, jlarkin@highlandsniptechnology.com wrote:
On Sat, 28 Mar 2020 15:00:02 -0700 (PDT), Roger_the_Dodger
cresswellavenue@talktalk.net> wrote:
For a USB oscilloscope I designed I had to get into signal processing.
I had to use a Fast Fourier Transform for displaying a frequency graph.

Did you program the FFT yourself from first principles, or did you
look up the code somewhere?

A Discrete Fourier Transform is easy to program from first principles,
as soon as you know what it actually is. FFT not so much, but having
done a DFT at least gives you the intuition about how an FFT is possible.

An FFT is not so hard. You just have to get your head wrapped around the permutations. I can't imaging being the guy who first came up with it. Likely recognized something in the sequence of sines related to something else in math he was familiar with. That's what the FFT is about, decomposing the DFT sines into operations that can be shared among all the harmonics.

Don't recall the name, but I think this was before it was very useful given the state of computing, so I don't know that the guy was looking for a way to speed up the DFT. I suppose a wikipedia search would answer that question.

I should have searched first. Tukey and Cooley specifically were looking for a way to speed up calculations. I was thinking this was invented in the 1950's, but it was 1965 when T and C published their paper having reinvented what Gauss discovered in 1805. Great minds think alike.

Anyway, in '65 computers were prevalent but sorely lacking in speed so the FFT was a big improvement.

--

Rick C.

++ Get 1,000 miles of free Supercharging
++ Tesla referral code - https://ts.la/richard11209

 

[Tom Gardner]

On 28/03/20 22:08, Joerg wrote:

On 2020-03-28 13:38, blocher@columbus.rr.com wrote:
On Friday, March 27, 2020 at 6:00:10 PM UTC-4, Rick C wrote:

[...]


So your work is not so much circuit design as it is system design?

I like to think I straddle circuits and systems.  I am decent at both
but certainly not an expert at analog.  The problem in my company is
that there is not enough work in circuit design to keep one always
busy.  I also think that most circuit problems are better solved
through a system approach.  If you get the system concept wrong, then
the circuit is going to be wrong.  If you know what you want at the
high level, it is easier to tell if your circuit design is adequate.


Amen!

Top-down is generally the only approach that really works. Now we'll have to
explain that to the next generations. All the ones who have served in the
military don't need to be told, they know this already.

You need top-down and bottom-up simultaneously.

Bottom-up allows you to reuse known working
components, processes and concepts.

Top-down on its own can lead to requiring
impossible components.

 

[Tom Gardner]

On 28/03/20 22:48, Phil Hobbs wrote:

Instinct is super useful for generating ideas.  We come up with some scheme by
instinct, but then test it by math.  The math involved is super familiar--what's
the noise floor, the bandwidth, the settling time, and so on.  It's the
familiarity that makes that seem like it's the same as design instinct, but it
isn't.

Very true, IMNSHO.

Practice without theory is blind fumbling.
Theory without practice is mental masturbation.
I exaggerate, of course.

 

[Tom Gardner]

On 28/03/20 23:00, jlarkin@highlandsniptechnology.com wrote:

I haven't solved a simultaneous equation or used matrix math since I
was forced to do that in college.

Who was it who said "the best result of mathematics
is that you don't have to use it all the time".

The fundamental maths leads to the mental short cuts
we use everyday in visualising circuits.

 

[George Herold]

On Saturday, March 28, 2020 at 6:42:16 PM UTC-4, Phil Hobbs wrote:

On 2020-03-28 16:06, George Herold wrote:
On Friday, March 27, 2020 at 6:25:46 PM UTC-4, pcdh...@gmail.com wrote:
How important is mathematics to you as an engineer?
Do you consider yourself an applied mathematician?
I would say that I do.  As an analog designer how much do you
use various mathematical concepts.

A lot of what I do is (a) for a given electro-optical design concept, calculate how good it _could_ be, (b) figure out how to get there, and (c) if that's a win, proceed, but if not, think up something better and goto(a)..

Significant amounts of math are required to get a good result, as well as a lot of lore and old fashioned crank-turning.

My favorite type of math is 'back of the envelope' calculations.
Those are fun... but it is always better with one or two other
people. (you can sorta check each other..)

Designing something cool with a few smart people at a whiteboard is the
most fun you can have standing up.

Amen,
George H.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com