I've got piles of voltmeters. Most of them are hilariously cheap, but when an accuracy of .1v is enough, the $3 voltmeter from harbor freight will do the job.
Voltmeters are grand, but they are very poor at showing you charge and discharge curves, and tell you absolutely jack about waveforms. That's where an oscilloscope comes in to play.
I have been lusting over the pocket oscilloscopes for a long time. And slowly the price has been coming down to the "why the heck not" level. About two weeks ago I decided that a DSO Nano had to be mine. $66 later, and four days of waiting, and it was.
Well there we go. You also get a little felt bag and a USB cable. But those are the big things you get in the package. No documentation at all!
They claim that it will accept 80v peak to peak. And that it has a 12bit DAC. Also they claim that it's got 1Msps.
I figure that means I can reliably look at 100khz signals.
On the subject of signals, it has this nice little test point on it. The test point is adjustable from 500hz to 2000hz.
Here's the DSO checking out it's own test signal. You can see it overshoot and the discharge curve. I wonder where that tail is coming from...
Now I wanted to try it with a really fun. The only thing I could think of that I had that would output a nice signal was my arduino. I loaded up the servo sweep sketch, and checked it out.
The servo signal is a pulse, every 20ms, that's between 1 and 2ms wide. I made a video of it. http://www.youtube.com/watch?v=YlIW7AvBg0Q
I posted on the EEvblog forum, asking for ideas of how to test, and exercise it. http://www.eevblog.com/forum/index.php?topic=4546.0
So it looks like I am going to make a joule theif.