Build a simple PC oscilloscope

[billy]

Hi all !

After I have bought my brand new usb logic analyzer :D

(have a look : http://www.usb-instruments.com/hardware-ant8.html)

which I need most, because digitals is my main hobby, I am thinking of building a simple pc oscilloscope as well, rather than buying a new one, because it is not critical for my needs. I want to write my own software (in Delphi) because most of the existing projects I have found are working only with win95/98 (not 2k/xp) and they don't have a professional interface, rather trivial I'd say.

So I have done a search on the net on this subject and I found the following projects (one to three stars * for complexity according to my opinion).

***http://kudelsko.free.fr/index2.htm
***http://alternatezone.com/electronics/dsoamk3.htm
**http://www.chocbar.demon.co.uk/
**http://www.ee.washington.edu/conselec/CE/sp95reports/guterman/final/scope1.htm
*http://scopeonpc.tripod.com/
*http://www.geocities.com/lptscope/hw.html

If somebody knows anything more, just let me know, the net is vast indeed :)

From all the above I have liked

http://www.geocities.com/lptscope/hw.html

and I have a question :

It uses the ADC0820 8-bit A/D which has an input of maximum +5volts, but it says that you can use a voltage divider in order to expand this range. Has anyone any idea how you can do that ? I prefer +-50volts because it is good for most applications (for instance PSU testing).

Thanks and I am waiting for your ideas ! 8)

[billy]

Found some more :

**http://www.leonardo.caltech.edu/~ee5x/eecs52/projects/scope/scope.htm

**http://www.fpga4fun.com/digitalscope.html

[billy]

And finally this is the best of all :

I have found schematics of a pc oscilloscope that works with
the PICOScope software !!!

http://free-ri.hinet.hr/abacus-ri/

from this thread :

http://groups.google.com/groups?q=pico+scope&hl=el&lr=&ie=UTF-8&oe=UTF-8&selm=aflbt6%242akr%241%40as201.hinet.hr&rnum=4

but I still want to expand the 5v input to 50 v... :-\

[ante]

Here is an attenator for pc oscilloscope that is used for soundcard input but it will probably be possible to apply in this case. The site is in Norwegian but the schematic is pretty simple.
http://home.online.no/%7Esondred/Gamle%20sider/attenuator.htm

Ante ::)

[fatoota]

hi

i just have an idea about what you said of +5 volt as a maximam i/p.
i think you can not give the pc souncard very high voltage or it will
burn, so you have to use attenuators, not neccessarily a voltage
divider and you may enter the attenuation level as a data to your
software.
that is all and i thank you that you started this interesting subject
and money saver.

[MP]

You are correct. Most PC devices will not allow more than 5 volts. Some cards have over voltage protection, but I would not use a higher voltage as a test to find out if yours has protection. You should decide what your highest voltage will be. Is it 5 Volts Pk-Pk?, 10 volts Pk-Pk? When you have this figured out, then you just use a small transformer to drop it down. Sound is an AC voltage, so transformers work great for these. There are several types used for telephone equipment that will work fine for you. perhaps you want a 2:1 or similar.

MP

[fatoota]

with the name of allah

i found this link that may be useful
http://www.ee.washington.edu/conselec/CE/sp95reports/guterman/final/scope1.htm#hard :)sherief-egypt

[mixos]

This topic has been also discussed here:

http://www.electronics-lab.com/forum/index.php?board=13;action=display;threadid=58;start=msg153#msg153

[edu38]

Billy:

please can upload traslation to eng of this site http://free-ri.htnet.hr/abacus-ri/.
I can`t understand anything......

regards from buenos aires

[Guest Kasamiko]

Is there any links for a simpler circuit without using ADC??

[ante]

Kasamiko,

My earlier post http://home.online.no/%7Esondred/Gamle%20sider/attenuator.htm is not using any ADC, it

[Guest Kasamiko]

OK,but got some question about it..
1. Where in my sound card i'm going to connect it? line-in?
2. The sound card is STEREO(of course) what particular channel i put it in?

Thanks again..

[ante]

Kasamiko,

How you connect it to the soundcard depends on which software you use. Most of them use the line-in for this but even the mic-input is sometimes used. Both channels is used to dual channel scope software. There is also some software for frequency measuring if you just want to count the waves and not look at them ;D which uses the same inputs.

Ante ::)

[Guest Kasamiko]

Thanks ANTE.. ;D I'm planning to use the Winscope and would like to "VIEW" the waveform of various Power inverter that we've been discussed here.. 8) 8)

[ante]

Kasamiko,

I hope to see some screen dumps of the waveforms on this forum soon then! Take care and don

[Guest Kasamiko]

Just wait and see.. ;) ;)
give me some time... ;D ;D