jurasz.de

Jarek Jurasz

COVID-19

There are plenty of plots out there to show the coronavirus pandemic already, but to really see the changes in exponential growth one needs logarithmic scale.

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Digital sampling of analog signals can produce surprising effects. It is tricky to explain and understand the frequency aliasing, which happens when undersampling. What is the aliased frequency? Why are there positive and negative frequencies in FFT, but only one Nyquist frequency?

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In electronics there is hardly anything simpler than a voltage divider circuit. Most people know that Vo = R2 / (R1 + R2) * Vi, where R2 / (R1 + R2) = f is the divider fraction. But it is not obvious how to choose the resistor values. You can start with one value, calculate the other one, get...

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Usłyszałem dziwny szelest w piwnicy. Patrzę... polna myszka siedzi sobie i ząbkami serek skrobie.

Nazwałem myszkę Jerry. Jak on tam wlazł? Jak by go tu złapać?

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My robotic lawnmower (Landroid M1000) stopped to work, complaining it is out of its work area. I knew the wire had some weak spots, but where? It is a few years old, several hundred meters long, hidden under grass... An interesting challenge.

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