When I power the arduino Micro boards (buyed in this website) I have a noise problem.
I'm powering the boards with an adjustable laboratory power supply, by the VI pin and GND pin. The voltage supplied is 10V.
When the board is connected to the power supply stopped, and I push the power button, I don't have any problem, but if the power supply is on, and I disconnect the possitive cable, and I connect it again, the 5V pin, has a lot of noise, and this noise is transmitted to the VI pin too. This happens too with the GND cable (disconnecting and connecting).
This can be seen in the oscilloscope:
Red channel is the VI pin, yellow channel is 5V pin.
This occours too with a 11,8V battery.
If I power up the power supply by the power switch (with no noise) and I adjust down the voltage under the 7V, also appears the noise, and continues although I go up the voltage to 10-12 V.
This happens in various Micro boards, and I proved in a Arduino Uno board with he same voltage regulator of the Micro, and never has noise in the Uno board.
This is the regulator in the Micro:
And this is the regulator in the Uno: