Chip with simple program for Toy

[John Larkin]

On Sat, 21 Jun 2008 12:13:09 GMT, "Talal Itani" <titani@verizon.net>
wrote:

It is nice if we can do mixed signal, but I am sure we have to pay much
more. We will use this scope in the product development lab, for embedded
work. The signal we are working with is 25MHz digital. Rarely we will look
at a clock of 100 MHz. So, I thought 350 MHz analog is what we should get.
Some Tektronix and LeCroy have a very short buffer. The ones with large
buffer start at $5,000. Is one brand better priced than the others?

Thanks.

For embedded stuff, get a color digital scope. Analog scopes have zero
buffer!

We have one of these...

http://www2.tek.com/cmswpt/psdetails.lotr?ct=PS&ci=13304&cs=psu&lc=EN

a 2024, and it's the best general-purpose scope around. The
fully-floating inputs are fabulous.

John

 

On Jun 21, 1:16�pm, "Talal Itani" <tit...@verizon.net> wrote:

Hello,

My company wants to buy an oscilloscope. �The scope that meets our needs is
around $7,000. �I am sure we can save much money if we buy a PC-based unit,
like Picoscope. �Do you have experience with PC based scopes? �Do you
recommend them for serious work?

Thanks

No, more so if you need a $7000 scope. Look on ebay if your that short
of cash.

 

[Tim Wescott]

Talal Itani wrote:

Hello,

I need to have a 4-layer board made, a prototype, 2 boards, nothing fancy.
I did some research in this newsgroup and I narrowed it down to Sierra Pro
Express, ExpressPCB, and AC Advanced Circuits. Do you think I made the
right choice? Do you have any recommendations? I would like to receive the
board 3-5 days.

T.I.


I have only ever used PCB express (NOT express PCB), and they have never

steered me wrong. Nor have they caused problems that I know of for my
one local client that uses them. They're fast, they're accurate, and if
your board comes back with problems it's because you put them there.

I can't speak to any of the others -- they may be even better than PCB
express (although there's not much room for improvement) or they may be
horrid.

http://www.pcbexpress.com/.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

 

[Phil Hobbs]

Icky Thwacket wrote:

LeCroys are bottom of the heap crap IMHO.

The digital Tektronix scopes we have on the other hand are superb - actually
designed to use as a scope, fast, reliable workhorses.

(John L. has some personal business wrt LeCroy--sort of like me with
Apple. Search back through the archives.)

Old LeCroys had some interesting features, though...I have an ancient
9400 that was the first digitizing scope to scroll the display at slow
speeds, like a chart recorder, and let you move the viewing window with
the horizontal position knob even while it was taking data. Very very
useful for some things.

They have never known how to build vertical amplifiers, AFAIK--at one
point they were selling a 2Gs/s scope with a 350 MHz vertical BW. Pathetic.

Cheers,

Phil Hobbs

 

[CBFalconer]

Talal Itani wrote:

I am sorry, I did not understand what you are telling me.

Please do not remove attributions. Those are the initial lines
that say "Whozit wrote". In addition avoid losing all quotations
from previous messages by top-posting. Your answer belongs after
(or intermixed with) the quoted material to which you reply, after
snipping all irrelevant material. See the following links:

<http://www.catb.org/~esr/faqs/smart-questions.html>
<http://www.caliburn.nl/topposting.html>
<http://www.netmeister.org/news/learn2quote.html>
<http://cfaj.freeshell.org/google/> (taming google)
<http://members.fortunecity.com/nnqweb/> (newusers)

--
[mail]: Chuck F (cbfalconer at maineline dot net)
[page]: <http://cbfalconer.home.att.net>
Try the download section.


** Posted from http://www.teranews.com **

 

[Dirk Bruere at NeoPax]

Talal Itani wrote:

Hello,

I was looking at the schematics for a DSP-based board, running at 100 MHz.
They have a tiny inductor with every bypass cap around the DSP. Do you
think this is necessary? This DSP has analog stuff built-in. If we do not
need analog, can the inductors be eliminated?

Seems overkill.
ADI reference designs don't use anything like that, although they follow
PSU chips with an inductor.

--
Dirk

http://www.transcendence.me.uk/ - Transcendence UK
Remote Viewing classes in London

 

[Hauke D]

Hi,

I've had good experiences with Advanced Circuits (http://www.
4pcb.com/). Make sure to use their free FDM service (http://
www.freedfm.com/), even if you don't end up going with them for
manufacturing.

ExpressPCB is only good for quick-and-dirty stuff. Their advantage is
that they're cheap and their design software is pretty simple to use,
but the big disadvantage is that it locks you in to their software.
Also I've never done 4-layer stuff with them; I believe they're also
kind of limited in that department. They're great for quick-and-dirty
stuff though.

Regards,
-- Hauke D


On Jun 21, 4:19 pm, "Talal Itani" <tit...@verizon.net> wrote:

Hello,

I need to have a 4-layer board made, a prototype, 2 boards, nothing fancy.
I did some research in this newsgroup and I narrowed it down to Sierra Pro
Express, ExpressPCB, and AC Advanced Circuits. Do you think I made the
right choice? Do you have any recommendations? I would like to receive the
board 3-5 days.

T.I.

 

[donald]

Talal Itani wrote:

I am sorry, I did not understand what you are telling me.

You seem to be hung up on price.

The picoscopes are ( see link) much higher or much lower then the $7,000.

You have yet to mentioned which $7,000 scope you are looking at, so we
can not compare the specifications of it with the picoscope devices.

So, I ask outright, which scope are you looking at for $7,000.

donald

Which Picoscope are you looking at:

http://www.picotech.com/oscilloscope-specifications.html

At $11,990.00 or $2,390.00, the price or specs are better with the
$7,000.00 scope, which ever scope that is.

donald

 

[donald]

Talal Itani wrote:

Hello,

I was looking at the schematics for a DSP-based board, running at 100 MHz.

Great, which DSP ?

They have a tiny inductor with every bypass cap around the DSP. Do you
think this is necessary?

Depends, which DSP ??

This DSP has analog stuff built-in. If we do not

need analog, can the inductors be eliminated?

Thanks,
T.I.

It must be a secret, what does the manufacture of the DSP say ??


donald

 

[mpm]

On Jun 21, 10:53�am, Hauke D <hau...@zero-g.net> wrote:

Hi,

I've had good experiences with Advanced Circuits (http://www.
4pcb.com/). Make sure to use their free FDM service (http://www.freedfm.com/), even if you don't end up going with them for
manufacturing.

ExpressPCB is only good for quick-and-dirty stuff. Their advantage is
that they're cheap and their design software is pretty simple to use,
but the big disadvantage is that it locks you in to their software.
Also I've never done 4-layer stuff with them; I believe they're also
kind of limited in that department. They're great for quick-and-dirty
stuff though.

Regards,
-- Hauke D

On Jun 21, 4:19 pm, "Talal Itani" <tit...@verizon.net> wrote:



Hello,

I need to have a 4-layer board made, a prototype, 2 boards, nothing fancy.
I did some research in this newsgroup and I narrowed it down to Sierra Pro
Express, ExpressPCB, and AC Advanced Circuits. �Do you think I made the
right choice? �Do you have any recommendations? �I would like to receive the
board 3-5 days.

T.I.- Hide quoted text -

- Show quoted text -

I've used ExpressPCB for small projects before, but always 2-layer
stuff.
I've never had a problem with them, or their boards.

As for being "locked-in" to their software, for an extra $60 (last
time I checked), they will send you the Gerber files. From there, you
can import to many of the other programs avail.

Also, I recall hearing a while ago that a lot of these PCB prototype
houses are all built at the same place anyway. So, while you might
see 10 different company names (i.e., resellers), the boards
themselves all come from the same place. Sorry, I don't remember the
names of the companies involved, and don't know whether ExpressPCB is
one of them.

-mpm

 

[John Larkin]

On Sat, 21 Jun 2008 15:56:31 GMT, "Talal Itani" <titani@verizon.net>
wrote:

Thanks. This is nice stuff, yet the buffer length (2.4k points) is too
small, I think, for our needs.

Why do you need a lot of buffer? I test and debug realtime uP-based
things, delay generators and arbs and such, with a Tek TDS2012, which
only has enough buffer for the screen you see.

At some point, a lot of memory is too much memory. It's easier to
think about why something's broken than to analyze a few million
stored events. Even easier to design it right in the first place, ie,
review the design more, debug it less.

John

 

[Tim Wescott]

Talal Itani wrote:

Hello,

I was looking at the schematics for a DSP-based board, running at 100 MHz.
They have a tiny inductor with every bypass cap around the DSP. Do you
think this is necessary? This DSP has analog stuff built-in. If we do not
need analog, can the inductors be eliminated?

Thanks,
T.I.


Search for newsgroup postings with "Jeorg" and "ground" or "grounding"

in them.

You'll get a load of (AFAIK) good opinions.

Inductors in series with the caps would tend to isolate the power supply
from noise in the DSP, but it would also create a bunch of odd
resonances. It's not how I'd want to isolate a power supply from a chip.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

 

[Tim Wescott]

Talal Itani wrote:
(Top posting fixed)

"Tim Wescott" <tim@seemywebsite.com> wrote in message
newsaydneRCzL9Vv8DVnZ2dnUVZ_uCdnZ2d@web-ster.com...
Talal Itani wrote:
Hello,

I need to have a 4-layer board made, a prototype, 2 boards, nothing
fancy. I did some research in this newsgroup and I narrowed it down to
Sierra Pro Express, ExpressPCB, and AC Advanced Circuits. Do you think I
made the right choice? Do you have any recommendations? I would like to
receive the board 3-5 days.

T.I.
I have only ever used PCB express (NOT express PCB), and they have never
steered me wrong. Nor have they caused problems that I know of for my one
local client that uses them. They're fast, they're accurate, and if your
board comes back with problems it's because you put them there.

I can't speak to any of the others -- they may be even better than PCB
express (although there's not much room for improvement) or they may be
horrid.

http://www.pcbexpress.com/.
So, there is PCBexpress, and expressPCB. Two different companies?


Yes, very different.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

 

[John Larkin]

On Sat, 21 Jun 2008 11:59:01 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

Icky Thwacket wrote:

LeCroys are bottom of the heap crap IMHO.

The digital Tektronix scopes we have on the other hand are superb - actually
designed to use as a scope, fast, reliable workhorses.

(John L. has some personal business wrt LeCroy--sort of like me with
Apple. Search back through the archives.)

Yup, they tried to put me out of business. Our friend at Los Alamos
didn't let them. That same guy, Harry, swears he was the one who
convinced Walter to take his CAMAC digitizer technology into the scope
business.

So, what's the story on Apple?

Old LeCroys had some interesting features, though...I have an ancient
9400 that was the first digitizing scope to scroll the display at slow
speeds, like a chart recorder, and let you move the viewing window with
the horizontal position knob even while it was taking data. Very very
useful for some things.

They have never known how to build vertical amplifiers, AFAIK--at one
point they were selling a 2Gs/s scope with a 350 MHz vertical BW. Pathetic.

I doubt they can spend as many megabucks on fast adc's as can Tek or
Agilent. Anybody can interleave a bunch of slow adc's.

They did a lot of strange stuff when Walter was still running things.
One was a scope with a ccd-like analog-storage shift register that
captured a small slice of transient data and time-shifted it down into
an adc. Occasionally. Spliced into the front end of a gp scope, it
made a very weird machine.

They also did a 1-diode sampler (Lumatron/typeN blast from the past,
fer sure) and a heterodyne-based sampling scope timebase. I think they
may have been mixed up with the PSPL shockline sampler fiasco... not
sure about that one.

LeCroy scopes seem to appeal to, err, a certain subset of the
population.

I have some Lumatron sampler schematics around here somewhere; even
some old rusty hardware.

John

 

[Tim Wescott]

Talal Itani wrote:

Hello,

My boss asked me to evaluate oscilloscopes and to recommend one. I know
Tektronix and LeCroy. Which is better? Are they any others? Ideally, we
would get a 4-channel scope at 300 MHz, with a 5 million sample record
length. Thanks for your advise.

T.I.


One of my clients has a top analog engineer who, when given the choice

between getting a dozen $3500 scopes so his whole department can work
without constantly stealing equipment vs. getting one $45000 scope so he
can measure really fast signals will immediately call Tek, Agilent and
LeCroy and ask for them to come out and bring their heavy iron.

For the absolute top of the line stuff LeCroy seems to be quite good --
their triggering sucks, but they can (some years) sample faster than
anyone else. At that price point _all_ the scopes are Windows based,
and they're all pretty bizarre bits of equipment if all you want to do
is see if a processor pin is wiggling at 100kHz.

For the 300MHz range I'd look to Tek or Agilent, although there's a new
top of the line Asian brand whose name I can't remember that may be a
good choice (they aren't really new -- they had a deal with HP to not
sell scopes in North America as long as HP sold scopes; as soon as HP
spun off Agilent they were there, chuckling over their good fortune).

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

 

[Tim Wescott]

mpm wrote:

On Jun 21, 10:53�am, Hauke D <hau...@zero-g.net> wrote:
Hi,

I've had good experiences with Advanced Circuits (http://www.
4pcb.com/). Make sure to use their free FDM service (http://www.freedfm.com/), even if you don't end up going with them for
manufacturing.

ExpressPCB is only good for quick-and-dirty stuff. Their advantage is
that they're cheap and their design software is pretty simple to use,
but the big disadvantage is that it locks you in to their software.
Also I've never done 4-layer stuff with them; I believe they're also
kind of limited in that department. They're great for quick-and-dirty
stuff though.

Regards,
-- Hauke D

On Jun 21, 4:19 pm, "Talal Itani" <tit...@verizon.net> wrote:



Hello,
I need to have a 4-layer board made, a prototype, 2 boards, nothing fancy.
I did some research in this newsgroup and I narrowed it down to Sierra Pro
Express, ExpressPCB, and AC Advanced Circuits. �Do you think I made the
right choice? �Do you have any recommendations? �I would like to receive the
board 3-5 days.
T.I.- Hide quoted text -
- Show quoted text -

I've used ExpressPCB for small projects before, but always 2-layer
stuff.
I've never had a problem with them, or their boards.

As for being "locked-in" to their software, for an extra $60 (last
time I checked), they will send you the Gerber files. From there, you
can import to many of the other programs avail.

Also, I recall hearing a while ago that a lot of these PCB prototype
houses are all built at the same place anyway. So, while you might
see 10 different company names (i.e., resellers), the boards
themselves all come from the same place. Sorry, I don't remember the
names of the companies involved, and don't know whether ExpressPCB is
one of them.

-mpm

So you have software that will go from a Gerber to a nicely laid out
schematic?

That's impressive.

I use real tools to do my schematic capture and layout, and for no extra
money I go to a regular PCB house to get boards.

(And PCB Express has it's own fab just 12 miles from me, so if I'm in a
_real_ hurry I can pick it up and shave 8-12 hours off of the process).

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

 

[John Larkin]

On Sat, 21 Jun 2008 16:06:02 GMT, "Talal Itani" <titani@verizon.net>
wrote:

Hello,

I was looking at the schematics for a DSP-based board, running at 100 MHz.
They have a tiny inductor with every bypass cap around the DSP. Do you
think this is necessary? This DSP has analog stuff built-in. If we do not
need analog, can the inductors be eliminated?

Thanks,
T.I.

Inductors don't generally help digital chips, and may actually reduce
timing margins. We do use ferrite bead+capacitor filters on the supply
rails of some fast opamps and adc's, to keep switcher noise and
other-channel crosstalk from sneaking in.

The best way to power big digital chips is with solid power planes,
reasonably bypassed. That will present lower rail impedances than you
could get by isolating the bypass caps on a per-pin basis.

John

 

[Hauke D]

So, there is PCBexpress, and expressPCB. Two different companies?

Yes.

Can ExpressPCB receive files from other PCB software?

No. (only netlists from schematic tools)

As for being "locked-in" to their software, for an extra $60 (last
time I checked), they will send you the Gerber files. From there, you
can import to many of the other programs avail.

Hm, didn't know that. Still, it should be noted that ExpressPCB can't
read Gerber files and one can only order from ExpressPCB through their
software, so I'd still consider that being pretty locked in. Plus, if
I wanted to spend a little extra money, I'd just go with something
like EagleCAD and one of the other fab places anyways I'd still
recommend ExpressPCB for any simple 2-layer designs where it's not
important for your design to be portable; I've used them several times
myself and it's quick and easy and decent quality. And I'm a big fan
of "keep it simple" interfaces like their software is.

Regards,
-- Hauke D

 

[Paul Keinanen]

On Sat, 21 Jun 2008 16:06:02 GMT, "Talal Itani" <titani@verizon.net>
wrote:

I was looking at the schematics for a DSP-based board, running at 100 MHz.
They have a tiny inductor with every bypass cap around the DSP. Do you
think this is necessary? This DSP has analog stuff built-in. If we do not
need analog, can the inductors be eliminated?

Are you sure that these are ordinary inductors or just a wire through
a ferrite bead?

While the ferrite will increase the inductance, a suitable ferrite
material is also quite lossy at higher frequencies, reducing the risk
for unwanted resonances with the capacitors.

Paul

 

[Phil Hobbs]

John Larkin wrote:

On Sat, 21 Jun 2008 11:59:01 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

Icky Thwacket wrote:

LeCroys are bottom of the heap crap IMHO.

The digital Tektronix scopes we have on the other hand are superb - actually
designed to use as a scope, fast, reliable workhorses.
(John L. has some personal business wrt LeCroy--sort of like me with
Apple. Search back through the archives.)

Yup, they tried to put me out of business. Our friend at Los Alamos
didn't let them. That same guy, Harry, swears he was the one who
convinced Walter to take his CAMAC digitizer technology into the scope
business.

So, what's the story on Apple?

When I was a graduate student at Stanford in 1984, Apple ran a promotion
where they sold 128K Macintoshes to students for about half price
($1100, iirc), along with the fairly nice 9-pin dot matrix graphics
printer for another $400. I had some code and a thesis to write, and I
thought it would be pretty useful.

That was a lot of money to me at the time--I was already married, and my
wife couldn't work in the US, so it was two of us living on a grad
student's stipend. I also knew perfectly well that you needed at least
half a megabyte of RAM to do anything useful (even with the GUI in ROM,
which was the big selling point of the Mac at that time). However,
Apple had a track record (then) of being relatively generous about
upgrades--they'd upgraded their Apple Lisa customers for a very
reasonable price, and with the Apple II/III, they'd shown that they
understood the importance of the educational market. So I was
optimistic that the 512K upgrade was going to be reasonably priced. I
mean, even then that was about $100 worth of memory chips, so how
expensive could it be?

What actually happened was that they charged $1000 for the upgrade,
which amounted to desoldering the 16 (DIP) 4164 chips and soldering in
16 41256s. They attempted to strong-arm everyone into ponying up by
saying that only factory upgraded machines would function with future
Apple products.

That turned into a bit of a habit with them--they recently did basically
the same thing to all the iPhone customers who changed their firmware,
except that my computer at least kept working.

After the shooting pains in the backside died away, I calmly decided
that I didn't want to play that particular game. I've never bought an
Apple product since.

Cheers,

Phil Hobbs