power adapter

I'm using Arduino mega board. This is my problem, I have WRT54G router and I have mounted LCD with Arduino mega via serial pins to it. I want to power both router and Arduni boards from the same power adapter. The adapter is 12v 1.0A . Is that harmful if I do this ? any solution ? thanx :)

You are probably OK, depending on how much current your Arduino circuit is drawing.

But to be sure, you should measure the current to the router and to the Arduino (with the LCD, etc.). If the total current (sum) is less than 1 Amp you are OK.

The router current is probably printed on the back, but the actual current might be less than the specified current because they usually want to allow some tolerance and they will also round-up, just to make sure you are using a power supply with a high enough rating.