PC as signal analyzer

[Engels]

Hi everyone
Since this is my first message on a diy forum, I would like to make a brief presentation of me:

[Noob]

Okay! here's my first question, made in verse form;
"But I, being poor, have only my computer; I have spread my computer under your feet (?); Tread softly because you tread on my computer ..ahahah!"
-cit. William Butler Yeats ...almost

Seriously, even if I can't be serious for more than 10 seconds, my question is simple; I saw that diy often involves the use of measuring instruments, such as oscilloscopes, multimeter, ecc.. "But I, being poor have only my computer" ... and my Daw on my computer has some of those instruments!  (I told you I can't be serious..)  ;D

So, how can I replace those big and expensive tools with a cheaper solution that is the digital measurement? Can the pc somehow turn magically into an oscilloscope? maybe it's a noobish question, but is it lecit since I'm the noobest noob of noobland?

Nice to know you all guys n'... (where are the dolls?) , and thanks a lot for the great plaza that all of you have builded!  :

 

[bruce0]

Tool    -    Can your PC be used instead.

Oscilloscope  - Yes, but you need a usb device that processes the signal for you (Velleman makes one), and in the end the cost of a used working oscilloscope or a cheap oscilloscope is usually close to or cheaper than the PC approach.

http://www.saelig.com/ has a variety of test equipment including low end and many pc versions.

If you are doing Analog Audio, you don't need a high speed scope, but two channel is nice to have (meaning it can analyze and display two channels at a time).

DVM - Digital Volt meter - No, I don't think it is practical to have your PC do it.  You can get a $5 DVM on Amazon or ebay.  You might find someday you want to measure inductance (L) or (capacitance) C, so some of these are LCR meters, and that can be nice, but not $5.  Still they don't cost as much as a scope unless you use a fluke (which is overkill for most things) but nice tools are nice tools.

Signal Analysis - Measuring THD and Frequency response.  A PC can do this using RMAA, and is usually cheaper than any other approach.  You can use your sound card (not great usually) or existing interface (pretty good), but there interfaces specifically designed for this (check out the "Chamber" thread on the QuanAsylum box) which cost more.

Soldering Iron - Using you PC as a soldering iron is not recommended.

Seriously, you can get really far on a soldering iron and a $5 DVM.  You can't get anywhere without them.  My suggested order of purchase would be temp controlled soldering iron, DVM, SCOPE, LCR meter.... But by far my favorite tool is my Hakko 808

 

[Engels]

Thank you for the answer, tragic and funny at the same time  :'(  ;D
I literally have exhausted all my funds and I don't really know if I'm going to finish the clone (yes, ssl clone) without many tools.
I hoped to find at least one utility for my pc, but it looks like I have to etch him due to his futile existance 

...too much humor? I hope you're not Bruce Willis who is going to kill me with an helicopter  :-\

Btw, I managed to find an old soldering station (a really really old weller, which is still very good) and some cheap DVM which works occasionally; I hope it's enough for now!

 

[audiomixer]

Or you can just download your favorite spice... tiNa ltspice whatever spice and stay in the theory ;-) no soldering required, scope included......  others avail too.... no affiliation!

of course it will not replace the real thing ;-)

- michael


ref:
http://www.ti.com/tool/tina-ti
http://www.linear.com/designtools/software/

 

[millzners]

I have a good spectrum analyzer and I still use a simple specrograph program and my Pc sound card input more often than not. Rarely does troubleshooting require more sophisticated tools than a good dmm, but that hasn't stopped me from stock piling old lab equipment.

 

[fenchelteefee]

Hi Engels and welcome to the Forum.

Me a noob too, but you may find interesting what I have to share.

Scope: So far I've researched the this topic, there're a few beginner USB-scopes out there. BUT:
1. Make sure they're galvanically isolated
2. Have high enough resolution
At one day, the bitscope gained interest. But getting into the 500$ area, a 'real' scope might be more appealing ..

Take a look at pmillets soundcard tester. It decouples your PC/Audio Interface from dangerous voltage peaks, so you just download SW testing tools like RMAA or Audiotester to measure Freq. Range,FFT, THD, RMS-AC and whatever. I think, with the right software, it can be turned into a scope, either. Total (component) price - 170$. Best thing for me is - it is completely DIY

Or you can just download your favorite spice... tiNa ltspice whatever spice and stay in the theory ;-) no soldering required, scope included (...)

Yeah, simulating circuits helps you to dive in a lot. I personally prefer Multisim. Love the user interface with 'hands on-style' measurement equipment.

 

[abbey road d enfer]

So, how can I replace those big and expensive tools with a cheaper solution that is the digital measurement? Can the pc somehow turn magically into an oscilloscope?

Just a bit of warning here. PC 'scopes are sampling oscilloscopes, that capture a picture of the signal at a certain time, or at certain intervals (depending on how fast is the sampling vs. signal frequency.
This gives some kind of idealized waveform, which is ok if you want to observe a nice continuous signal, but masks transients. A real anlog 'scope would "see" things that a PC-based one would not.
One of the nice things with USB scopes is that they can be used with a portable (running on its batteries) and be galvanically isolated.

 

[Engels]

Thanks everyone for the suggestions!
I still do not have an oscilloscope but with my soldering station and a new DVM I hope I can go far with my projects  ;D

So, I've just one last theorical question:
Do you think that in the future there will be more digital-based solutions instead of classic analog devices?
I'm just thinking about what happened with mobile phones, which became smartphone, and have replaced a lots of instruments like cameras, calculators, almost every computer application.
well, I don't really need an answer, my mind is rambling...
So, this topic can be closed after all 

Thanks ocne again

 

[gemini86]

There are actually a few decent android app scopes that are good for looking at a 1Khz sine wave. Good for troubleshooting, but not for real world measurements.

 

[bruce0]

So, I've just one last theorical question:
Do you think that in the future there will be more digital-based solutions instead of classic analog devices?

I think there are digital based solutions... and I and my fellow Luddites are fighting them tooth and nail  ;D

 

[gemini86]

You can get a decent scope for cheap on ebay. (cheap being a relative term) I bought a BK Precision 2560 (totally obsolete, can't even get a manual from BK) for like 100 bucks. It's a 60mhz analog scope with a digital capture function.

 

[VictorQ]

Even the most expensive stuff uses the pc for analysis. The tough part is getting a decent digital signal in there..
http://www.bksv.com/products/frontends/lanxi.aspx