Hello!

For some time ago i downloaded a oscilloscope to my pc that read both channels (L+R) on the soundcards "line in" and displays it on the PC-mointor. My question is how high the impedance is and how much voltage i can put in to the soundcard before it "burns"?

 

do you happen to remember where you downloaded it from? was it free?

 

radialspel,

You should use an attenuator for this, this is a Norwegian site but I am sure it’s no problem.
http://home.online.no/%7Esondred/Gam...attenuator.htm
This site is full of interesting things, even software for scope.

Ante :roll:

 

check out
http://xoscope.sourceforge.net/

it is very good and this opensource projuect have pretty much done all the work for you. There is also the cct you need to interface to yr sould card to protect it and all.

Very good

 

Hi:
am trying to do the same project u r doing now, I bought yesterday a cheap sound card (it's not a bad one but it is an old one), u may ask me why to buy a new sound card rather than using the local sound card in my PC, the answer is that to protect my local sound card from damage that may occur by high signals and DC currents, so I suggest that u must connect the sound card u want to use as an oscilloscope via a capacitor to block the DC currents and that is what am going to do to.
U can download an oscilloscope software for windows from this website:
http://polly.phys.msu.su/~zeld/oscill.html

 

check out my xoscope link above. even if you do not use linux and have another windows based software the link I have supplied has a circuit that you can build to protect your soundcard as well as correct impedance

 

You can find some Soundcard oscilloscopes software that require no hardware to be attached to the pc. You need only one sound card and some connectors to drive the signal at the input of the sound card of your pc. Check here: http://www.electronics-lab.com/downloads/pc/index.html

Additional pc oscilloscopes:

Non Commercial
http://www.ee.washington.edu/consele...nal/scope1.htm
http://www.geocities.com/huz_52/
http://home.planet.nl/~m.f.hajer/
http://www.discovercircuits.com/O/oscilloscopes.htm
http://www.geocities.com/tangmonster...cilloscope.htm (ISA bus)
http://www.dansworkshop.com/Homebuil...lloscope.shtml (TV based)
http://www.geocities.com/SiliconVall...56/articl3.htm (with LEDs)
http://www.electronic-projects.net/E...pe/index.shtml (TV based)
http://www.intio.or.jp/jf10zl/tvosc.htm (TV based)

Commercial:
http://www.qkits.com/serv/qkits/vell...ges/pcs500.asp
http://www.scope4pc.com/
http://www.acqiris.com/Products/Cougar_main.html
http://www.picotech.com/oscilloscope.html
http://www.designnotes.com/Specials0702.htm
http://www.usb-instruments.com/ (USB)
http://www.arborsci.com/Products_Pag...cilloscope.asp
http://www.linkinstruments.com/oscilloscope21.htm
http://www.bitscope.com/

 

Thanks mixos for posting these wonderful website links.

Very unfortunately I have not been able to find one suitable for my intended applications: temperature recording. In other words the oscilloscope would need to accept DC signals. I have tried half a dozen or so different PC scopes but none could do that. Reason? This is because these scopes make use of the sound card as the data input device and I have found that the sound cards on all my PCs are DC-blocked!

I am just not sure if I can find a sound card in the market that can accept DC input signals --- and that should solve my problem!

Any advice please?

Or any other ways to display DC signals on the scope without the very expensive hardware please?

Thanks.

Olihou

__________________
I am NOT a llama !

 

The relevent words are 'sound card', there's no reason for it to be DC coupled, and lots of reasons for it not to be - I doubt you'll find a sound card that's DC coupled. If you can get a really old one (with sensible size components?) you may be able to DC couple it?.

For your application, which is datalogging, a PIC based, serial connected, system (as at the start of this thread) would be ideal.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

Hello Nigel

Thanks for your comments and advice. I agree that PIC microcontrollers can make good stand alone (not relying on a PC) data loggers. This is something I like to do later.

Before I got the time to learn PIC, I would still prefer to use readily available PCs, if I can find a way. One suggestion is to employ a simple VCO, so that the voltage level to be measured is converted into a corresponding frequency of an oscillator. The signal is fed to the line-in of the sound card. What we need to do now is to write a program, say in Visual Basic, to monitor the frequency and convert it back to voltage data.

How can I write such a program? I have the basic programming knowledge if Visual Basic, but I have no idea how to get the frequency values out from the sound card!

I need help --- any one please!

Thanks !

Olihou

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I am NOT a llama !

 

I think your simplest answer here is going to be some form of A to D converter connected via the serial or parallel port for a visual Basic program to be able to get direct 'voltage' signals to display ...
An A-D would be simpler to build than a VCO even if you had an A-D chip and something like a MAX232 to convert to RS232 format (these two items come prepacked inside some microcontrollers!)

Take Nigel's advice - a microcontroller with an integral A-D converter, spewing forth the digital data would be cheap and easy to replace if you inject too much and kill it. The VB program required for this would be simpler than trying to measure frequencies.
It would be easy to make a multi-input system like this, four or five analogues into a PIC, a simple two wire RS232 link to the PC.

__________________
I need a memory upgrade ...
My head is full !

 

Thanks a lot , Mechie

I agree with you and Nigel that a microcontroller with an ADC could certainly be programmed to be an analogue signal data logger. However my idea of employing a VCO as ADC is from an article titled

"VCO Transforms Sound Card Into Precision DC-Coupled ADC" at

http://www.elecdesign.com/Articles/A...2641/2641.html

I can see a benefit of this approach is that the VCO circuit could be easily isolated (say by a single photo-coupler) from the PC --- as needed in some applications such as that for dispalying the ECG signal. I would not give up PC either as I would like to do a lot of data manipulation on the PC.

The original circuit uses an IC XR-2206. I am thinking of one goood enough but with much simpler circuit using LM331.

Matlab has been used for the programming. Unfortunately I have facilities to do Visual Basic, but not Matlab, and I do not see any reason why Visual Basic could not do the same job!

This is where I got stuck ---- I need the advice how I could program the sound card wirh VB, or where I could get such information.

Could any one help please !!!

Olihou

__________________
I am NOT a llama !

 

Circuit of LM331

Attached Images

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I am NOT a llama !

 

Mr. Olihou,

why can´t You use a software like http://polly.phys.msu.su/~zeld/oscill.html wich also is a PC's sound card as an Analog-to-Digital Converter (ADC) instead matlab or VB project?

 

COOOOOOOOOOOLLLLLLLLLL!!!!!!!
I didn't know that there were pc oscilloscope software available for free!thanks for the sites, i'll go check it out!