Are low/lower cost USB Oscilloscope's any good?

[qrk]

Hi,

I am just trying to mess around with electronics stuff, and I don't know too
much, but I've put a circuit or two together with help from this forum and
others. I've got a fluke DMM and clampmeter, but I'd really like to be able
to scope some stuff sometimes. I just don't know if I could part with the
money for a portable scope like a fluke 123 however just for playing around.
I have some questions and appreciate any suggestions for what might be good:

1. Do most scopes have decent voltage input on them? For example, can you
hook most of them up to line power (120vac or 240vac)? I am assuming the
fluke can do this no sweat, but I don't know.

2. I also see a bunch of references to X10 probes. Are these used to
reduce the voltage to something a scope can use, for example 240VAC -->
24VAC ?

3. Do you have any recommendations for a scope that works on a notebook
that is relatively low cost that has decent features (keep in mind I have no
idea what features you would want in a scope).

I would even consider some of these scopes that are free based ones that
work with a sound card, but my question is, what type of voltage input can
you get with a microphone jack???

Thanks!

Alan

Get a real analog scope. Hunt on Ebay for a Tektronix scope. You can
pick up a 465B for pretty cheap (buy it now prices of $200). They were
the work-horse scope of industry. I still use my 465 to this day,
preferable to my new Tek digi scope for certain applications or trying
to set up the digi scope on unknown signals. My 465 is getting close
to 30 years old.

Also, an old 465 can provide a great learning experience if you read
the manual or/and need to fix the scope.

 

[Nico Coesel]

But why are they so slow? At least the ones I have seen were. We
designed 400MSPS converter boards even back in the late 80's and early
90's. It ain't rocket science.

The problem is what to do with the data. Sampling and storing data in
some memory is the easy part. Gettting it from the memory onto a
screen in a meaningfull way is not so easy. I'm working on one and
everything is about ready except for the sampling itself.

 

[Joerg]

The problem is what to do with the data. Sampling and storing data in
some memory is the easy part. Gettting it from the memory onto a
screen in a meaningfull way is not so easy. I'm working on one and
everything is about ready except for the sampling itself.

Back in those days that was even worse because fast static RAM was
incredibly expensive. So, we often used lower cost RAM and staggered it.
Data was written into it in a round-robin fashion, read out in a normal
way one bank at a time and then pieced together by software. Or in our
cases mostly by a scan converter hardware. And yes, these were realtime
systems where there was very little pause between acquisitions.

 

[Phil Allison]

"Joel Kolstad"

"Phil Allison"


The long number in that link is apparently a session ID that has expired,
but searching for "Q1803" from dse.com.au gets you there.

** Try this instead:

http://www.dse.com.au/cgi-bin/dse.storefront/4581d4e80084b7a22744c0a87f9c077d/Product/View/Q1803

Here in the U.S., I've seen same 'scope on eBay, e.g.,

** That is not the same scope and it is priced much higher.

http://cgi.ebay.com/NEW-MCP-10MHz-C...yZ104247QQrdZ1QQssPageNameZWD1VQQcmdZViewItem.> It is rather cute and might make a lot of sense to keep around a lab forsome quick troubleshooting, but for someone's first and only scope I reallythink the money would be better spent on a used Tek box.** What you "really think" is not of much value to anyone. Old Teks are basically boat anchors.> I wonder how much storage tubes cost to manufacture? The Q1803 wouldprobably have a lot more takers if it could freeze the trace so that itwould work for troubleshooting, e.g., non-repetitive serial communications.** Not a requirement at all for most scope users. Digital geeks have an extraordinarily narrow idea what "troubleshooting"is......... Phil

 

[Phil Allison]

"Phil Allison"

"Joel Kolstad"


** Try this instead:

http://www.dse.com.au/cgi-bin/dse.storefront/4581d4e80084b7a22744c0a87f9c077d/Product/View/Q1803

** That is not the same scope and it is priced much higher.

( delete troublesome Ebay link )

It is rather cute and might make a lot of sense to keep around a lab
forsome quick troubleshooting, but for someone's first and only scope I
reallythink the money would be better spent on a used Tek box.

** What you "really think" is not of much value to anyone.

Old Teks are basically boat anchors.

I wonder how much storage tubes cost to manufacture? The Q1803 would
probably have a lot more takers if it could
freeze the trace so that it would work for troubleshooting, e.g.,
non-repetitive serial communications.

** Not a requirement at all for most scope users.

Digital geeks have an extraordinarily narrow idea what "troubleshooting" is.




.......... Phil

 

[Barry Lennox]

Hi,

You might want to start off with a real scope, I still use Tek 453 and
454s I got a few years ago for $100 and $125. No doubt they are even
less now. Both are still excellent performers and are used most days.

However, as another poster pointed out the ones at
http://www.cleverscope.com/ are very good if you want a "all-digital"
USB scope. I have trialled one against a low end Tek scope and the
Cleverscope was superior in nearly every respect. Cleverscope has a
good comparison chart against the low end Agilent and Tek scopes on
their website. As far as I can see, it has not been "selectively
tweaked" to present a true, but misleading picture.

Barry Lennox.

 

[Joel Kolstad]

** That is not the same scope and it is priced much higher.

You're correct, I looked closely and there are some minor differences. The
actual specs appear the same, though -- I'd wager they're made by the same
OEM, and it's the same basic design.

The price is double, but comparing the price of anything on eBay to the
pricing in a brick and morter store (especially when you have to throw in a
currency conversion!) is irrelevant.

** What you "really think" is not of much value to anyone.

You're entitled to your opinion.

Old Teks are basically boat anchors.

Depends on how old you get... I'm not thinking the really old 465s, more like
the 2000-series. (I'd say 2465B, but that costs a *lot* more than what the OP
is after.)

** Not a requirement at all for most scope users.

That's a very arbitrary statement. We could both come up with lists of
applications where being able to freeze the display is anything from pretty
worthless to an absolute necessity, but it's a reasonable statement that --
everything else being equal -- I can't imagine anyone would *not* want to have
such an ability in their scope.

Digital geeks have an extraordinarily narrow idea what "troubleshooting" is.

For many of them, sure... but consider that these days the "high-end" digital
guys are doing things like troubleshooting 10Gbps data streams, and this
requires plenty of extraordinarily high-end equipment. There's a good reason
why Tek's "Which oscilloscope is right for you?" page --
http://www.tek.com/products/oscilloscopes/selection_chart.html -- lists
"high-speed serial" first on their 15GHz real-time scopes.

---Joel

 

[Phil Allison]

"Joel Kolstad"

"Phil Allison"

You're correct, I looked closely and there are some minor differences.
The actual specs appear the same, though -- I'd wager they're made by the
same OEM, and it's the same basic design.

** What a fool like YOU would foolishly wager is of no relevance either.

The price is double, but comparing the price of anything on eBay to the
pricing in a brick and morter store (especially when you have to throw in
a currency conversion!) is irrelevant.

** More asinine bollocks - it a simple fact.

Aussie DSE stores are selling the scope I referred to at half the price US
eBayers are being asked to pay for the mail order one you found.

You're entitled to your opinion.

** You are just full of narcissistic & irrational opinions.

Depends on how old you get...

** Yawn - more silly obfuscation.

That's a very arbitrary statement.

** It is a very simple fact.

( snip more of this asinine geek's opinionated crapology)

For many of them, sure..

** I was talking about YOU - you dumb fuckhead.

No wonder your thinking is so narrow - with that extraordinary pointy head
of yours.

LOL !





........ Phil

 

[Joel Kolstad]

Hi Phil,

Aussie DSE stores are selling the scope I referred to at half the price US
eBayers are being asked to pay for the mail order one you found.

Correct; my point was that -- in this particular case -- the price doubling
doesn't imply they're not still 99% the same scope.

Here in the U.S., PlayStation 3's that retailed for $599 were going for
several thousand dollars the week after they first came out. I bet someone
down in Oz even paid that much... maybe you?

** It is a very simple fact.

You're completely out of touch with reality, then.

** I was talking about YOU - you dumb fuckhead.

Well, given that I don't do much digital design these days -- other than a bit
of glue logic here or there --, your argument doesn't really apply.

---Joel

 

[Phil Allison]

"Joel Kolstad " = ASD fucked imbecile

"Phil Allison"


Correct; my point was that -- in this particular case -- the price
doubling doesn't imply they're not still 99% the same scope.

** It certainly implies the DSE scope is FAR better value for money -
dickhead.

You're completely out of touch with reality, then.

** ROTFLMAO !!

You and "reality" have never even visited the same universe - fuckhead.

Well, given that I don't do much digital design these days -- other than a
bit of glue logic here or there --, your argument doesn't really apply.

** Dear Mr Kolstad - you are a fucking ass.

Piss off.




......... Phil

 

[jasen]

The long number in that link is apparently a session ID that has expired, but
searching for "Q1803" from dse.com.au gets you there.

Here in the U.S., I've seen same 'scope on eBay, e.g.,
http://cgi.ebay.com/NEW-MCP-10MHz-C...yZ104247QQrdZ1QQssPageNameZWD1VQQcmdZViewItem .

not the same scope, it's 3lb heavier, and has buttons where the DSE one has
sliders (and runs on 120V),

Phil found the exact same scope on farnell's site for three times the price.
they were out of stock, (possibly inventry knows more than sales)
the brand this time is "CALTEK",

Farnell have another one: brand "DIGIMESS", even more expensive, but the only
images for it are a blurry catalogue photo (pdf page) and the line art in
manual (pdf), it looks like the same scope to me.

It is rather cute and might make a lot of sense to keep around a lab for some
quick troubleshooting, but for someone's first and only scope I really think
the money would be better spent on a used Tek box.

how easy is it to get parts for those old Teks?

 

[jasen]

not the same scope, it's 3lb heavier, and has buttons where the DSE one has
sliders (and runs on 120V),

Phil found the exact same scope on farnell's site for three times the price.
they were out of stock, (possibly inventry knows more than sales)
the brand this time is "CALTEK",

Farnell have another one: brand "DIGIMESS", even more expensive, but the only
images for it are a blurry catalogue photo (pdf page) and the line art in
manual (pdf), it looks like the same scope to me.

the published schematic is slightly different though.

 

[vasile]

For many of them, sure... but consider that these days the "high-end" digital
guys are doing things like troubleshooting 10Gbps data streams, and this
requires plenty of extraordinarily high-end equipment. There's a good reason
why Tek's "Which oscilloscope is right for you?" page --
http://www.tek.com/products/oscilloscopes/selection_chart.html -- lists
"high-speed serial" first on their 15GHz real-time scopes

"Which oscilloscope is rigth for your pocket" maybe ?


Here is good one as a price/performance if you like to use your laptop.
http://www.dynoninstruments.com/

But i'm searcing for a PCMCIA PC scope, do you know any ?

greetings,
Vasile

 

[David L. Jones]

Hi,

I am just trying to mess around with electronics stuff, and I don't know too
much, but I've put a circuit or two together with help from this forum and
others. I've got a fluke DMM and clampmeter, but I'd really like to be able
to scope some stuff sometimes. I just don't know if I could part with the
money for a portable scope like a fluke 123 however just for playing around.
I have some questions and appreciate any suggestions for what might be good:

What you want for starters is a proper analog scope. A 20MHz dual trace
model is a basic starting point, or even the 10MHz single channel Phil
pointed out.
You can get cheap 2nd hand scopes on eBay and surplus gear sellers.

1. Do most scopes have decent voltage input on them? For example, can you
hook most of them up to line power (120vac or 240vac)? I am assuming the
fluke can do this no sweat, but I don't know.

DON'T muck around with probing the mains unless you know exactly what
you are doing.
If you want to do it *safely* you need a proper high voltage
differential isolating probe, and these are not cheap.

2. I also see a bunch of references to X10 probes. Are these used to
reduce the voltage to something a scope can use, for example 240VAC -->
24VAC ?

x10 probes are used for probing higher speed signals. In most normal
cases you would use a x10 probe.

3. Do you have any recommendations for a scope that works on a notebook
that is relatively low cost that has decent features (keep in mind I have no
idea what features you would want in a scope).

If you want to capture weaveform (for example, analysing a serial
digital signal) then you need either a digital stoage scope (DSO), or a
PC based one. In any case, you should get a real analog oscilloscope as
well for general purpose use.

With DSO's, memory depth and sample rate are the top two requirements.
The more the better.

I would even consider some of these scopes that are free based ones that
work with a sound card, but my question is, what type of voltage input can
you get with a microphone jack???

If you really want to work on high voltage gear, you MUST get a proper
differential probe. Anything else mixed with lack of experience will
either kill you or your equipment.

Dave

 

[joseph2k]

Well, I have also seen the same sort of thing on the commercial side,
too, where a boss didn't want to upset the budget apple cart to get
something he felt the 'boys' should be able to just whip up out of teh
parts room...

Charlie

Bog, reminds me of when my boss wanted me to build a digitizing 'scope. It
was about the time the early 6-bit and 8-bit flash converters first hit the
market. Doing the design was not the problem, i even could get the parts i
wanted; getting the hours to actually build it was. It turned out, of the
available personnel only i had the necessary combination of expertise to do
the various tasks required to build a useful unit. (yes i was both tech and
engineer) and management decided that my time was too valuable elsewhere to
complete the project. You are invited to design working pre-trigger
recording at near logic limit speed as well. (at the time 20 MSPS, today,
about 6 GSPS)

 

[Charlie Edmondson]

Charlie Edmondson wrote:




Bog, reminds me of when my boss wanted me to build a digitizing 'scope. It
was about the time the early 6-bit and 8-bit flash converters first hit the
market. Doing the design was not the problem, i even could get the parts i
wanted; getting the hours to actually build it was. It turned out, of the
available personnel only i had the necessary combination of expertise to do
the various tasks required to build a useful unit. (yes i was both tech and
engineer) and management decided that my time was too valuable elsewhere to
complete the project. You are invited to design working pre-trigger
recording at near logic limit speed as well. (at the time 20 MSPS, today,
about 6 GSPS)

And, sometimes it gets built in house due to politics...

I was working on toll roads, and we needed a 'presence' detector, i.e.
Is there a car there, or not? We had a great laser sensor from a
manufacturer ($10K per unit...) but only covered about 3 feet. We
needed to cover 12 feet of lane, three lanes wide, so this would use 12
units. BUT, this was to replace the only commercial unit they had found
that was $100 PER LANE, so management wanted to see if we could do it.

Now, the obvious solution would be to just hook up all four sensors
(they connected with just two wires for sensor line a and b) to the lane
control computers, and do the combination in software. However, the
lane control computers were with a different branch of the company, and
their software 'assumed' they would just get a single line saying car
present, or not. So, they were going to just put out the $300K for the
commercial units.

So, I went to the boss, and said that I could put together a simple
interface and logic board to interface with the units, and save us
$150K. So, in this case, I volunteered for the job. He gave me 6 weeks
to get a prototype out. I also suggested that I could add some
intelligence by using programmable logic (an eprom state machine) but
that would take a little longer. He gave me an additional 4 weeks to
add the programmability.

I designed and built the prototype in four weeks. It was tested and
heading out to the test track in 6 weeks... with three different
programmable state machines!

Charlie