Stability of arduino boards

[Grumpy_Mike]

Frequency response.

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De-coupling Tutorial

De-coupling Once you get more than a handful of active components together you need to de-couple the power supply. What this is, and why, is described here. The problem When an otherwise good design works, but is erratic, unreliable or just goes crazy then nine time out of ten it is the power supply de-coupling. And you will find that the tenth time, turns out to be power supply de-coupling as well. So what is it, and why is it needed? Basically when an integrated circuit works it works by swi…

One where using ceramic ones instead of mylar ones made a difference
http://forum.arduino.cc/index.php?topic=343563.10