Earlier I wrote a long blog post that condensed down the path I’ve taken to buying my first oscilloscope. I hadn’t decided what to buy though., so this post will continue with more of the decision making process.
But first, a short review of the ground I covered in my earlier post. I explained that I needed an oscilloscope to help me better understand why circuits work, or don’t work. I’m not just doing this for fun, my goal is to start designing and building some useful circuits of my own. I covered how I started figuring out what my options were for an entry-level scope, in order to better understand what I should be thinking about.
At the end, I’d concluded that buying a cheap compact oscilloscope like the DSO Quad wasn’t a good idea (not capable enough to be useful for long, and not cheap enough given its limitations), and why a USB scope wasn’t going to save me any money (the meager savings from omitting a screen and controls are offset by the higher prices that come with limited volumes).
I started by considering Rigol scopes like the dual-channel Rigol scopes sold by Adafruit, or the dual-channel. Gratten scope sold by Sparkfun. At this point though, I’ve all but ruled out those options. The truth is, at $390-460, they are all within my budget, and with 50-100MHz of bandwidth, they can all do what I think I’m going to need them to, which is to deal with ~1-2MHz signals from switch mode power supplies. The problem is, while I don’t know much about oscilloscopes, I’ve already figured out that I have better options.
A hint of this is already obvious among the three scopes on Adafruit and Sparkfun. Both the Rigol scopes have 5.7″ 320x24o displays, while the Gratten has a 7″ 800×480 display. Of course, even I know that while a large screen is better, screen size probably shouldn’t be the first, or even fifth thing to judge a scope on. Things like bandwidth, sample rate and memory size, on the other hand, are much more important, and here the Gratten scope matches or beats the Rigol offerings sold by Adafruit. For $400, it offers 100MHz bandwidth and it does so for just $10 more than the 50MHz Rigol scope and $50 less than the 100MHz Rigol. That might be enough to convince them to buy the Atten scope from Sparkfun, me, on the otherhand, I get curious about what else is out there.
What I found is daunting. There are so many options, I’m tempted to buy the Gratten GR1102CAL from Sparkfun and get on with things, but that wouldn’t be like me. I press on.
One of the things I notice in my research is that a lot of these scopes have similar model names. This isn’t exactly a surprise though, because often the numerical part of the name represents some fundamental characteristics. Taking the Sparkfun and Adafruit offerings as an example:
The last/right-most digit on all three scopes is the number two (2). If one were to check out more models of scope from Rigol and Atten (among others), you’d probably recognize that this is the number of input channels. Two channels is common among entry level scopes. Higher end scopes sometimes have 4 channels.
With enough perspective, it becomes obvious that the middle two digits often indicate the bandwidth offered by the scopes: 100MHz or 050MHz in the case of these examples.
The meaning of the first digit seems to indicate the model line, and the letters at the end often indicate key options, like memory size.
The similarities don’t end with just the numbers though. Model names between manufacturers seem very similar. Sometimes even the names seem similar. For example, there is the Gratten GR1102CAL sold by Sparkfun, and there is another manufacturer called Atten, which has a model SDS1102CAL; the specs are pretty much identical between the two. In fact, the case is too, down to the position of the front USB port. Oh, and then there is the Siglent SDS1102CAL, also with remarkably similar specs and appearance.
There is an explanation though, which is that some manufactures sell the same or similar equipment under multiple brands and/or sell equipment which other brands sell under their own label. This simplifies things somewhat, if you can keep everything straight.
I learned something else too, which is that while the Rigol scopes Adafruit sells were revolutionary revolutionary for the value they offered when they first came out, they are a bit long in the tooth now. Last year Rigol released the DS1000Z series, which occupies the same price point the DS1000 series originally did when it came out.
I’ve learned a lot more about the options available for good entry level scopes. Now I’m really sure that I don’t know what to buy. Narrowing down my options will have to be the subject for a new post