PC Scopes there are quite a number of scopes for the diy would you recomend one?

PC Scopes are getting popular online any experiences? would you recomend
one? any additions for example to increase voltage input?

-- Bernard

*** Sent From/Enviado desde: http://groups.expo.st ***

 

Depends on what you mean by PC scopes. Do you
mean a hardware gadget that interfaces to the PC?
Or something that uses your existing sound card?

As the author of Daqarta for DOS (and the upcoming
Daqarta for Windows), I can say that sound card
systems (like Daqarta) can never be a complete
replacement for a benchtop scope, because they
have limited sample rates that confine them to
audio-range work. However, if you are doing
work in this range they can be very useful for
things like spectral analysis and synchronous
signal averaging for noise reduction. These are
things that are available on pricier benchtop scopes,
but not on the entry-level models you are likely
to find. So one approach is to get a cheap benchtop
scope for high-frequency and digital work, and
use a sound card system for audio work.

With a sound card scope you can measure audio
distortion better than many expensive benchtop
units, simply because souond cards have 16-bit
ADCs and many high-frequency benchtops and
PC hardware add-ons are only 8-bit. It is *so*
nice to be able to make tweaks to an amp or oscillator
and watch what happens to the distortion as you
adjust a pot in real-time.

Another advantage of sound cards is that they
make outstanding audio signal generators, both
for things like the above distortion measurements,
or just general testing. (You may want to check out
my free DaqGen for Windows; it's only a signal
generator, but it does all sorts of waveforms and
modulation tricks.)

One downside of sound cards is that they don't
go down to DC. If you don't mind a little wiring
job, you can make your own 8-bit "sound card"
for Daqarta for DOS that uses the LPTX driver.
This circuit is typically a handful of resistors that
you plug into the printer port. It goes down to
DC and samples at up to 50 kHz.

As far as increasing the input voltage range,
you can do that on any scope, either benchtop,
PC add-on, or sound card, using voltage dividers.

Best regards.





Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Home of DaqGen, the FREEWARE signal generator

 

could you please send me more infor on this scope bob and perhaps if you
have any links to other because i am really intrested in this and probably
i\'ll build anyone i find because i am really intrested

regards

what i am mainly intrested is in more info about soundcard scopes their
limits and voltages and parrallel port scopes the same info

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Server Error 500 on the above site.
How does one reach it?
Thanks, mike


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site not working !

 

Sorry, just discovered that after I posted.
I am hoping the Web host can fix it soon!

Best regards,




Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Home of DaqGen, the FREEWARE signal generator

 

It's back up now. Sorry for the inconvenience.

Best regards,


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Home of DaqGen, the FREEWARE signal generator

 

The Daqarta / DaqGen site is back up. (Sorry for
the inconvenience.)
www.daqarta.com

No links there to other sites.

But there's lots of into there on Daqarta, including the
complete Help system for the main program, plus
each of the drivers. If you go to the downloads page
and scroll down a bit to the driver section, you'll find
the Help link for the LPTX driver. That has schematics,
theory, and construction tips. There's info on how to
set it up for desired input ranges.

Note that Daqarta for DOS run only under real-mode,
so you need Win9x or earlier; Win2K and XP won't work.
(That's why I'm working on Daqarta for Windows!)
In general, the LPTX approach is not suitable for
Windows, which does not allow real-time operation
like DOS does. So there will likely never be an LPTX
driver for Daqarta for Windows... sorry!

So, if you have a rel-mode DOS system and would
enjoy a bit of construction, this might be a fun project.
But it will never compete with a real hardware scope
on anything except cost!

Best regards,


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Home of DaqGen, the FREEWARE signal generator

 

For low-frequency stuff (<120 Hz), I recently learned of a cheap ($25
U.S.) A/D converter. Details are here:

http://www.dataq.com/194.htm

The main features:

Plugs into serial (RS-232) port of a PC
4 voltage channels that handle +/-10 V
20 mV resolution (not the greatest, but good for this price)
60 / sec sampling rate for each channel, or combine all 4 channels for
up to 240 samples/sec
Software is included.

The advantage of this over sound-card software is that it reproduces
low frequency and DC signals. A disadvantage is the upper limit of 120
Hz (when using 240 sample/sec mode).