Tag Archives: review

Entry level oscilloscopes – what can you expect

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You can buy 1Gsamples/s oscilloscopes now for a few hundred euros. But there are also entry-level scopes available in the range of 800-1000€. Does it make sense to invest in the more expensive devices? Check out this comparison of two Rigol devices:

There is another interesting thing about the Rigol DS2000 series featured in this video: there is a key generator out that allows you to use the features of the expensive devices even with the base device. All features are enabled and disabled just by software. Is it legal? We don’t know? But a more interesting question is: What will Rigol do about it? My guess is, that Rigol is aware of the issue and is happy about it. It’s great marketing: Sell the same product at different price points depending on the willingness to pay.

FreeCAD – some experiences

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FreeCAD-logoI was looking for a 3D CAD program for OS X for a limited budget. After looking into some demo versions of commercial programs and some open source programs I decided to look into FreeCAD.

Let’s start with the good things: The parametric modeller has a steep learning curve. But when you finally understood how everything works it is extremely powerful.

Another big advantage of FreeCAD is its availability on Linux, Windows and OS X. There are only a few other CAD programs that are also available on these platforms.

If you’re not a designer, but a programmer, you will like the scripting interface. You can create, modify objects using Python. If you have experience with some programming language, it is easy to learn the Python basics needed to control FreeCAD.

Unfortunately FreeCAD has also some disadvantages:

The CAD kernel that is used is OpenCascade. Unfortunately this kernel still has some bugs. Some functions work not as expected, some will even crash the program. After filing a bug report for a specific problem, the FreeCAD team answered: “this is a bug of the underlying CAD kernel, we cannot fix it”. This can be a big risk for large design, because you never know when you will find a bug that is critical for your design.

The other big problem is speed. The whole application runs single threaded and working with models that consists of more than a few blocks can be extremely slow. I created a 3 dimensional logarithmic spiral that consists of about 500 objects. The calculations are simple, but the program stills runs more than a minute on my PC.

Conclusion: If you’re a programmer or you work with simple 3D models, FreeCAD might be a program to look into. If you work with complex models, the speed and the bugs can be serious disadvantages.