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Re: How limitting do you think a scope would be if it were limitted to 35 volts?

James M.\(Jim\) Geidl
 

There is one other feature that I think is kinda neat with these USB units,
you can be up to 16' from the PC. If you have limited desk space you don't
have to have the bulk of the equipment right next to you.

Jim



As for the drawback of having to have a computer to use the scope, well
chances are really good that a computer is never more than 15 steps from
where I am anywhere in the shop or office where I do all this stuff. Heck,
in the shop I have 2 computers and in the office I have 3 (1 laptop and 2
desktops).

While I certainly do like storage and recording features, the biggest gain
for me is that I "Should" be able to trust the display.
I can't trust my real scope and that is a very bad thing :-(

Chris










Yahoo! Groups Links
Re: Remote control ideee....

g0ysorg
 

Alarms that emit a female's blood curdling scream get the most
attention...


--- In Electronics_101@..., Tavys Ashcroft <bigtex@...>
wrote:

Since nobody really responds to audible car alarms anymore, and
everybody hates them, it would make more sense to have the sensors
in
the car alarm trigger, via RF signals, a message sent to a pager,
phone, or audible alarm within the house. This would allow for more
discrete notification, and possible tracking of the vehicle. It
would also be possible to set up two-way communications between the
vehicle and base station in home or cell phone so the owner could
yell at the theif personally. That would be fun.

I would love to hear the end of loud car alarms. Especially the
Viper ones that cycle through the same tone patterns over and over
and over while I'm trying to sleep.

-Tavys
Re: Best way of replying

Andreas Stemmer
 

rtstofer wrote:
Perhaps something like: Kommen Sie herein <-> You come in
In German the verb (kommen) comes before the subject (Sie) whereas in
English it follows the subject.
But these are two different sentences. "Kommen Sie herein" (or better "Komm herein" if you're talking to a friend) is an imperative which would be translated to "Come in". "You come in" would be "Sie kommen herein", subject first, then verb.

But I have to admit, that there are many cases in which the word order is different in German than in English. Although probably everybody understands what I mean, the sentences I write may sound awkward to a native English speaker. I'd really appreciate it, if those who know it better corrected more of those errors. Only this way it's possible for us non-native speakers to learn it properly.

Andreas
Re: How limitting do you think a scope would be if it were limitted to 35 volts?

Leon Heller
 

----- Original Message -----
From: "Stefan Trethan" <stefan_trethan@...>
To: <Electronics_101@...>
Sent: Saturday, October 07, 2006 4:11 PM
Subject: Re: [Electronics_101] Re: How limitting do you think a scope would be if it were limitted to 35 volts?


On Sat, 07 Oct 2006 16:39:21 +0200, rtstofer <rstofer@...> wrote:

As Stefan points out, the 50 Msps limits the frequencies that can be
sampled. The absolute maximum signal that can be accurately sampled,
according to the Shannon Sampling Theorem, is 1/2 of the sample
frequency or about 25 MHz. And that requires that the signal be
periodic. All bets are off for one shot signals.

I don't think the shannon theorem is very useful when looking at scopes.
It can be applied for real-time sampling (like for audio) but it doesn't
apply to sampling scopes (equivalent time) for repetitive signals.

If you use many periods to sample a signal there is no requirement to
sample at least twice each period. You can sample now, and again 5 periods
later plus t, and then ten periods later plus 2*t, and then 20 periods
plus 3*t, doesn't matter.
You can buy 100GHz sampling scopes with only 10Msps. Clearly not
fulfilling Shannon.
<>

Neither is it all that practical for real-time sampling scopes, unless you
correctly apply it, which you did, to the highest harmonic you are going
to need. But estimating which harmonic you might want isn't much more
accurate than guessing how many points you'd like to have in a period of
your signal.
To be pedantic, the sampling frequency only has to be twice the *bandwidth* of the sampled signal.

Leon
Re: How limitting do you think a scope would be if it were limitted to 35 volts?

Stefan Trethan
 

On Sat, 07 Oct 2006 16:39:21 +0200, rtstofer <rstofer@...> wrote:

As Stefan points out, the 50 Msps limits the frequencies that can be
sampled. The absolute maximum signal that can be accurately sampled,
according to the Shannon Sampling Theorem, is 1/2 of the sample
frequency or about 25 MHz. And that requires that the signal be
periodic. All bets are off for one shot signals.

I don't think the shannon theorem is very useful when looking at scopes.
It can be applied for real-time sampling (like for audio) but it doesn't
apply to sampling scopes (equivalent time) for repetitive signals.

If you use many periods to sample a signal there is no requirement to
sample at least twice each period. You can sample now, and again 5 periods
later plus t, and then ten periods later plus 2*t, and then 20 periods
plus 3*t, doesn't matter.
You can buy 100GHz sampling scopes with only 10Msps. Clearly not
fulfilling Shannon.
<>

Neither is it all that practical for real-time sampling scopes, unless you
correctly apply it, which you did, to the highest harmonic you are going
to need. But estimating which harmonic you might want isn't much more
accurate than guessing how many points you'd like to have in a period of
your signal.

ST
Re: How limitting do you think a scope would be if it were limitted to 35 volts?

Don
 

The sampling rates on the low-end digital scopes and pc scopes has kept me away from them. for the $300 figure that was mentioned,
you should be able to get a very good working tektronix 4xx series scope. The 465 is probably the most common, and easy to find a good working, clean unit. And as far as recording, there are camera setups just for that which are also easily obtained and used. you may wish to check out the Yahoo group "Tekscopes" for more info.

Don

----- Original Message -----
From: rtstofer
To: Electronics_101@...
Sent: Saturday, October 07, 2006 8:39 AM
Subject: [Electronics_101] Re: How limitting do you think a scope would be if it were limitted to 35 volts?


--- In Electronics_101@..., "lcdpublishing"
<lcdpublishing@...> wrote:
>
> Horses stopped, but I had no plans of pulling the trigger right away
> as I don't have the money.
>
> I really don't understand that specification at all
> though "50Msamples"
>
> Sounds like something that someone made up to represent something.
>
> Is it 50 million samples per second or something like that?
>
>

As Stefan points out, the 50 Msps limits the frequencies that can be
sampled. The absolute maximum signal that can be accurately sampled,
according to the Shannon Sampling Theorem, is 1/2 of the sample
frequency or about 25 MHz. And that requires that the signal be
periodic. All bets are off for one shot signals.

A square wave is composed of the fundamental frequency (let's say 100
kHz) and all of the odd harmonics clear up to daylight (a really high
frequency). To get a decent leading edge, you probably need up
through the 7th harmonic but I'm not going to do the math. So, for
the 100 kHz signal you need to accurately display 700 kHz or sample at
1.4 MHz. No problem - the box samples far faster than that.

However, when you get to frequencies above a very few MHz, the
sampling rate isn't fast enough. At some point, that is a problem
with all digital scopes.

I have often thought about buying a PC scope. One of the reasons is
that I like the idea of having a logic analyzer come along for the
ride. And for those that worry about Linux versus Windows, Bitscope
has the answer. FWIW, you can download the software and try it over
the Internet by connecting to a device back at the factory.

Anyway, I kind of like the Bitscope 310 (www.bitscope.com) but it only
samples at 40 Msps.

Richard
Re: Msg from Moderator - trying out a phpBB forum for HomebrewPCBs

Derryck Croker
 

On 8 Jun 2006, at 19:18, Steve wrote:

I have a start on a phpBB forum for HomebrewPCBs.


Eventually I will point to that location.
Is this still at the starting gate, or has it gone back to the stables?

--

Cheers

Derryck
Re: How limitting do you think a scope would be if it were limitted to 35 volts?

 

--- In Electronics_101@..., "lcdpublishing"
<lcdpublishing@...> wrote:

Horses stopped, but I had no plans of pulling the trigger right away
as I don't have the money.

I really don't understand that specification at all
though "50Msamples"

Sounds like something that someone made up to represent something.

Is it 50 million samples per second or something like that?

As Stefan points out, the 50 Msps limits the frequencies that can be
sampled. The absolute maximum signal that can be accurately sampled,
according to the Shannon Sampling Theorem, is 1/2 of the sample
frequency or about 25 MHz. And that requires that the signal be
periodic. All bets are off for one shot signals.

A square wave is composed of the fundamental frequency (let's say 100
kHz) and all of the odd harmonics clear up to daylight (a really high
frequency). To get a decent leading edge, you probably need up
through the 7th harmonic but I'm not going to do the math. So, for
the 100 kHz signal you need to accurately display 700 kHz or sample at
1.4 MHz. No problem - the box samples far faster than that.

However, when you get to frequencies above a very few MHz, the
sampling rate isn't fast enough. At some point, that is a problem
with all digital scopes.

I have often thought about buying a PC scope. One of the reasons is
that I like the idea of having a logic analyzer come along for the
ride. And for those that worry about Linux versus Windows, Bitscope
has the answer. FWIW, you can download the software and try it over
the Internet by connecting to a device back at the factory.

Anyway, I kind of like the Bitscope 310 (www.bitscope.com) but it only
samples at 40 Msps.

Richard
Re: PIC interrupts

 

--- In Electronics_101@..., "Leon Heller"
<leon.heller@...> wrote:

----- Original Message -----
From: "rtstofer" <rstofer@...>
To: <Electronics_101@...>
Sent: Saturday, October 07, 2006 7:16 AM
Subject: [Electronics_101] Re: PIC interrupts





In the second case, the code is probably not portable. The Microchip
assembler include files contain the only correct definitions for the
various registers and bits.
He also used

goto $-1

Leon
--
Leon Heller, G1HSM
Suzuki SV1000S motorcycle
leon.heller@...

Yes... It was late and I was thinking about mentioning that but I
fell asleep first.

PC relative branches (as in '$ - 1') are highly problematic when
trying to port the code to a pipelined architecture such as one of the
ARM processors. It isn't going to work and will take a lot of time to
debug.

It also complicates adding or removing statements from the loop -
assuming the target is more than 1 instruction away.

That coding style is so bad that I cringe every time I see it.
Besides serving as a perfectly good bad example, it will set
programming and new users back about 40 years.


Richard
Re: How limitting do you think a scope would be if it were limitted to 35 volts?

Stefan Trethan
 

On Sat, 07 Oct 2006 15:22:25 +0200, lcdpublishing <lcdpublishing@...> wrote:


Is it 50 million samples per second or something like that?

Yes.

That's the number of measurement points this thing takes. To properly picture a signal you need many points along it, if there aren't enough the shape will not be correct.
The 1Gs periodic thing is for repetitive signals. If you imagine a sine the scope takes say 10 points from one period, and then 10 from the next, but slightly shifted in time, and 10 from the next, again slightly shifted. In the end it puts them all together to display the one single sine. But what you really get is images from several periods. The signal better had the same shape in all periods or it won't make any sense. Of course with something that isn't repetitive the scope can't take data from the next period to throw it all together, it has to sample "real time", and that it can only do at 50M points a second.

ST
Re: How limitting do you think a scope would be if it were limitted to 35 volts?

 

Horses stopped, but I had no plans of pulling the trigger right away
as I don't have the money.

I really don't understand that specification at all
though "50Msamples"

Sounds like something that someone made up to represent something.

Is it 50 million samples per second or something like that?




--- In Electronics_101@..., "Stefan Trethan"
<stefan_trethan@...> wrote:

HOLD YOUR HORSES!
or $.

I didn't carefully read the specs of it, it has only 50Msamples
real time.
The 1Gsample is some faked-up oversampling number.

I would _NOT_ buy this scope, unless you are _sure_ 50Msamples is
good
enough for you.
It will be OK for most measurements, but don't expect to measure
more than
maybe 5Mhz, if that, single shot.
Usually when using micros you don't look at base clock signals,
but
instead at much lower speed outputs and communications. So for
most stuff
it will be enough. And for looking at clock signals, those are
periodic so
you get the full analog bandwidth.
Now my digital plugin (7D20) also has 40Msamples, and it is good
for most
work, but in the rare case that i need more i have a 7633 sitting
below it
that looks at and stores 100Mhz analog if i need it. I wouldn't
give that
away.

I thought that is to good to be true and re-read the specs....
Almost had to revise my opinion about PC scopes there, but no such
luck
they are still made cheaply.

Of course i have to take back my statement that this would be
comparable
to a TDS220, which has 1Gs if i remember right. A _real_ Gs.

ST
Re: Best way of replying

dmb112503
 

I think I have read enough comments on this subject (which seems to
be off topic to me.) I have never seen a group get so anal. Top
post/bottom post! Get a life! It doesn't matter as long as it is
written clearly enough to be understood.

--- In Electronics_101@..., Derryck Croker <derryck@...>
wrote:


On 6 Oct 2006, at 14:55, AnaLog Services, Inc. wrote:

I have never seen top posting create as many problems as bottom
posting does.
I think that that has been debunked thoroughly - it just needs a
little attention on the part of the person replying, that's all.

--

Cheers

Derryck
Re: How limitting do you think a scope would be if it were limitted to 35 volts?

Stefan Trethan
 

HOLD YOUR HORSES!
or $.

I didn't carefully read the specs of it, it has only 50Msamples real time.
The 1Gsample is some faked-up oversampling number.

I would _NOT_ buy this scope, unless you are _sure_ 50Msamples is good enough for you.
It will be OK for most measurements, but don't expect to measure more than maybe 5Mhz, if that, single shot.
Usually when using micros you don't look at base clock signals, but instead at much lower speed outputs and communications. So for most stuff it will be enough. And for looking at clock signals, those are periodic so you get the full analog bandwidth.
Now my digital plugin (7D20) also has 40Msamples, and it is good for most work, but in the rare case that i need more i have a 7633 sitting below it that looks at and stores 100Mhz analog if i need it. I wouldn't give that away.

I thought that is to good to be true and re-read the specs....
Almost had to revise my opinion about PC scopes there, but no such luck they are still made cheaply.

Of course i have to take back my statement that this would be comparable to a TDS220, which has 1Gs if i remember right. A _real_ Gs.

ST
Re: How limitting do you think a scope would be if it were limitted to 35 volts?

Stefan Trethan
 

Maybe you can diagnose/fix the HP scope some day with this scope.
Often you need a scope to fix a scope.
At least you will be able to compare the display and make sure if and where the HP is malfunctioning.

The biggest problem i have with the PC scopes is that usually the sampling rate is _way_ low, like a few Msamples at best. This one says it has 1Gsample, which should make a very useful scope (even comparable to Tek TDS220 maybe).
The other thing is of course the user interface. Even though i have a 19" tft mounted in the center of my electronics bench and input devices right in a drawer under the table surface i'm still not sure if i'd like a PC scope. I guess it would be OK, although i don't understand why they don't put the basic controls on the case of the PC scope. After all stuff like input attenuators really needs mechanical switches (or relays) and there seems little advantage in software control. Even if - the cost of say 3 rotary encoders and 10 pushbuttons would be minimal. Then the PC screen could just serve as display (and for advanced settings), while the basic controls of voltage and time would be analog, but what do i know...
That you have all the data immediately there in the PC without any importing, and that you get math-intensive functions (measurements, FFT) basically for free are very tempting though..

ST

On Sat, 07 Oct 2006 13:50:49 +0200, lcdpublishing <lcdpublishing@...> wrote:

Thanks for all the comments, suggestions and opinions.
While I agree that having a real scope is probably the best way to
go for the long term, I think having a scope that I can trust to be
accurate and working is more critical in the short term.
I bought that HP scope used on E-Bay - great price etc. I cleaned
it up, bought some probes and checked it out the best I can and
fixed a few broken dials. While it does work good sometimes on one
of the two channels, it's when it doesn't work good that screws me
up completely.
If I had the experience to know if what I am seeing is a problem
with the scope versus a problem with what I am checking, it wouldn't
matter much.
A good example of this is was when I tried to watch the output from
a stepper driver - I had everything set correctly on the scope and
video taped the display, but the display didn't make sense to anyone
else. There have been a number of times now when I have wanted to
measure something only to give up because it simply didn't "Work".
It appears that much of what I am doing and probably will continue
to do is in the realm of micros and related projects (Motion control
and so on). The fastest micro I know of that I can work with is
20mhz, so the 60mhz of this "Simulated scope" is certainly good for
the range of stuff I work with.
The recording ability is very important to me. Just having the easy
ability to take a "Screen shot" and post that image for help in
analyzing what is there is a huge benefit for a newbie like me.
As for the drawback of having to have a computer to use the scope,
well chances are really good that a computer is never more than 15
steps from where I am anywhere in the shop or office where I do all
this stuff. Heck, in the shop I have 2 computers and in the office
I have 3 (1 laptop and 2 desktops).
While I certainly do like storage and recording features, the
biggest gain for me is that I "Should" be able to trust the display.
I can't trust my real scope and that is a very bad thing :-(
Chris
Re: How limitting do you think a scope would be if it were limitted to 35 volts?

 

Thanks for all the comments, suggestions and opinions.

While I agree that having a real scope is probably the best way to
go for the long term, I think having a scope that I can trust to be
accurate and working is more critical in the short term.

I bought that HP scope used on E-Bay - great price etc. I cleaned
it up, bought some probes and checked it out the best I can and
fixed a few broken dials. While it does work good sometimes on one
of the two channels, it's when it doesn't work good that screws me
up completely.

If I had the experience to know if what I am seeing is a problem
with the scope versus a problem with what I am checking, it wouldn't
matter much.

A good example of this is was when I tried to watch the output from
a stepper driver - I had everything set correctly on the scope and
video taped the display, but the display didn't make sense to anyone
else. There have been a number of times now when I have wanted to
measure something only to give up because it simply didn't "Work".

It appears that much of what I am doing and probably will continue
to do is in the realm of micros and related projects (Motion control
and so on). The fastest micro I know of that I can work with is
20mhz, so the 60mhz of this "Simulated scope" is certainly good for
the range of stuff I work with.

The recording ability is very important to me. Just having the easy
ability to take a "Screen shot" and post that image for help in
analyzing what is there is a huge benefit for a newbie like me.

As for the drawback of having to have a computer to use the scope,
well chances are really good that a computer is never more than 15
steps from where I am anywhere in the shop or office where I do all
this stuff. Heck, in the shop I have 2 computers and in the office
I have 3 (1 laptop and 2 desktops).

While I certainly do like storage and recording features, the
biggest gain for me is that I "Should" be able to trust the display.
I can't trust my real scope and that is a very bad thing :-(

Chris
Re: How limitting do you think a scope would be if it were limitted to 35 volts?

Gaurav Verma
 

Hi

I am using this exact model. It is wonderful piece of equipment and I would
suggest you to go for it. t has scope + spectrum analyzer + transient
recorder. It also let's you bring your data into excel and allows you to
take screenshots.

you may be able to use attenuation probes when it comes to measuring large
voltages. at $300 it is a steal I would suggest go for it.


Regards
Gaurav

On 10/6/06, rtstofer <rstofer@...> wrote:

--- In Electronics_101@...<Electronics_101%40yahoogroups.com>,
"Leon Heller"
<leon.heller@...> wrote:

----- Original Message -----
From: "lcdpublishing" <lcdpublishing@...>
To: <Electronics_101@... <Electronics_101%40yahoogroups.com>

Sent: Friday, October 06, 2006 11:48 PM
Subject: [Electronics_101] How limitting do you think a scope would
be if it
were limitted to 35 volts?



How limitting do you think a scope would be if it were limitted to
35 volts?

There is a PC based scope - USB interfaced, that I have been
eyeballing. It isn't cheap, around $300.00, but it is dual channel
and rated up to 60 Mhz which should be fine for me.

The real kicker that I am liking about the PC scopes is recording.
For some reason, I think that is important, not sure why, but I do ;-
)

The drawback is that voltage limit though. While most everything I
check is 5~12 volts, I have checked the output of my Stepper Driver
and that is at 41 volts.

This is the one that is being considered

A second-hand analogue scope would be about the same price and would
be a
lot more useful.

Leon
--
Leon Heller, G1HSM
Suzuki SV1000S motorcycle
leon.heller@...

Exactly right! I bought a used Tektronix 485 via eBay for less money
than that and it has 350 MHz of bandwidth. No storage, no recording,
just a plain, ordinary, analog scope. But it's what I have always wanted.

Richard
Re: PIC interrupts

Leon Heller
 

----- Original Message -----
From: "rtstofer" <rstofer@...>
To: <Electronics_101@...>
Sent: Saturday, October 07, 2006 7:16 AM
Subject: [Electronics_101] Re: PIC interrupts




In the second case, the code is probably not portable. The Microchip
assembler include files contain the only correct definitions for the
various registers and bits.
He also used

goto $-1

Leon
--
Leon Heller, G1HSM
Suzuki SV1000S motorcycle
leon.heller@...
Re: Best way of replying

Derryck Croker
 

On 6 Oct 2006, at 14:55, AnaLog Services, Inc. wrote:

I have never seen top posting create as many problems as bottom posting does.
I think that that has been debunked thoroughly - it just needs a little attention on the part of the person replying, that's all.

--

Cheers

Derryck
Re: Best way of replying

Derryck Croker
 

On 6 Oct 2006, at 14:08, LT Ron Wright wrote:

It can get confusing sometimes weeding out the message and the answers.
Well, my email client automatically puts in a marker at the start of each line of quoted text when I reply, and it also indicates how many levels of quoting have already taken place. I don't think I've ever used one that didn't do this.

--

Cheers

Derryck
Re: Best way of replying

Derryck Croker
 

On 6 Oct 2006, at 14:05, LT Ron Wright wrote:

It really gets to me when they say left and really mean right.
When my wife says that, I say "you mean the OTHER left"! :-)

--

Cheers

Derryck
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