A plain unmodified WinPC will do a lot as test equipment with the right software. I am interested in links, which I will group in my blog, that will do various functions.

For example, the AAC book has a link that will allow you to use the sound card as a very primitive oscilloscope. I would recommend building a buffer circuit to protect your PC, and this is not for high voltage applications. But in many cases it would be nice to see if a circuit were oscillating or clipping.

http://www.allaboutcircuits.com/vol_6/chpt_4/14.html

Winscope

Another interesting program I have run into is speech analyzer, which will tell you the frequency and other important information about speech. It would have other uses however.

http://www-01.sil.org/computIng/sa/

Note, ACC has firm restrictions on pirated or owned software, keep this in mind for your recommendations.

 

I have been pretty impressed with this freebie for audio work : http://www.sillanumsoft.org/

And, IMHO, it's worth logging in (as a guest - no need to register) to get access to the V.2012 beta version, which is really excellent.

As an audio 'scope and spectrum analyser, it's up there with some of the 'paid for' software ....again, IMHO of course!

 

My rig is shown here. It works well for lab bench range voltages, ie. less than 10V. The software (which was free) and computer I use are so old I won't bother detailing them.

The point is, you can cobble together a very useful, 2-channel "oscilloscope" for almost no cost. Not useful except in the audio range, but that covers a lot of bench stuff.

 

My rig is shown here. It works well for lab bench range voltages, ie. less than 10V. The software (which was free) and computer I use are so old I won't bother detailing them.

The point is, you can cobble together a very useful, 2-channel "oscilloscope" for almost no cost. Not useful except in the audio range, but that covers a lot of bench stuff.

Wayneh, do you feel it's necessary to use actual probes? Or would shielded cable have a reasonable response? Say, run cable to old meter probes... I'd like to set something like this up, too (have an old 766MHz PC, ha ha), and have messed around with Analyser. Only interested in AF...

How about an input buffer? Unknown what my sound card impedance is (ESS Allegro). Thought about doing a dedicated divider (x10) followed by a buffer, just to ensure the safety of the card if I hit it with something over 5V. I'm assuming DC will be blocked (but can add an output cap if that's advisable)...

 

I once build an AC skin conductance meter using PC and a sound card

 

Wayneh, do you feel it's necessary to use actual probes?

No, my "probes" are just little alligator clips on the other end of that coax cable. I think there might be shielding up to the point where the probes break out into separate wires. I do not think the last few inches of those individual wires are shielded.

 

Thanks, we'll give it a try! I know the accuracy will be suspect due to stray capacitance working with resistance to filter etc., but this might work "well enough"...just to see clipping and for making comparisons and so on.

 

My cardex seems to have got lost around 2000 on this subject, but I'm sure there was also a Wireless World series on this.

E = Elektor
Map = Maplin magazine
ETI = Electronics today International
EPE = Evereday and Practical Electonics

 

This one is a free, small and very simple PC based signal generator;
http://www.natch.co.uk/downloads/SigJenny/SigJenny.html

for audio frequencies. At higher frequencies 12-20kHz the sine output shape from the PC sound card is not great, as the sound card is driven with samples at 44.1kHz (and 20kHz gives only 2.2 samples per cycle).

But for a free fast download it's a working PC based audio signal generator, with no hardware needed (as it uses the PC's internal sound card).

 

This one will do quite a bit as a function generator, too. Killer sweeps, 2 tones at once, etc:

http://www.sillanumsoft.org/


I made the leap and got a Tektronix 60MHz scope on Ebay last night. $90 delivered, which seems to be a good price for that generation. For what I do, I will likely never need anything over 1MHz! There are quite a few on there worth checking out if you are going to take the hobby to 'the next level'...

 

here's a good one that I like for a Total Harmonic Distortion Analyzer:

http://www.ymec.com/hp/signal2/thd.htm