Jitter VS GND

Hi,

since it looks for me like a new topic I continue http://arduino.cc/forum/index.php/topic,58650.0.html here.

The same problem can be reproduced with a common power supply.

The DCF77 does not get a clean signal, when attached to the power connector. The code is tested on the USB connection and random runs make a red light flash permanently when the signal is locked, which is the change for testing this setup:

http://gonium.net/md/2006/11/05/arduino-dcf77-radio-clock-receiver/index.html

Is there a DIR (Do it right) for grounding the arduino in an independent setup to get the jitter away?

I am about 200 km away of the Station in Frankfurt.

As I described in the mentioned link it works with the current setup using a plastic computer with an USB Power source or the Aluminum Computer with another USB Cable which has a ferrite bead.

Using the power only port it behaves exactly like when I use the Aluminum Macbook with an USB cable without an ferrite bead.

The only change in this setup is the power source, which make it work in one case but not in the other one.