I really am a sucker for mailshots (hmm. Perhaps I shouldn’t put that in the blog). Anyhoo, I got a mailshot from Cool Components advertising the above (or actually the slightly cheaper version 2 which you don’t seem to be able to get any more). So I bought one. It is a tiny digital storage oscilloscope which costs around 80 quids or so. I reckon this is extremely good value. It has an SD card that you can use to store waveforms and the whole thing is powered by a Cortex A3 and open source, so you can even put your own firmware in there if you fancy it. It is powered from a rechargeable battery and will go up to 1 MHz which for me is fine.
If you are not sure what an oscilloscope is, it lets you “see” electrical signals. It draws a plot of the voltage in the signal as it changes over time. The original ones used a cathode ray tube that drew a single dot on the screen. The dot was moved across the screen at a regular rate by a timebase generator and the value of the voltage in the signal was used to control the height of the dot. If the signal was regular then you could take a a peek at the waveform and see what it was doing. Newer ones are of course digital. The input voltage is converted into numbers which are then used to draw a graph on the screen.
Sometimes, when a circuit just doesn’t work you need to take a look at what is happening. A voltmeter will tell you if there is anything on the wire, but not how it is changing over time. If you have any hardware aspirations I think a little device like this is a pretty good investment, and it only costs around the same as a couple of video games.