This is just a quick update: The boards have arrived yesterday and I had a first quick look. So far I have spotted just two small problems that can be fixed:

• The footprint for the MQ135 is a bit small. It's a tight fit but the sensor can be soldered to the board. I will fix this in a future version of the board.
• The ground pin is not connected directly to the ground plane but only via a small trace - too small for the current of the gas sensor. The good news is that this can be fixed with 2cm of wire and I will also change this in Rev 1 of the board. No idea why I have not spotted that during the layout ;)

I have checked most of the other connections and not found an other problems but so far I have not tested the boards with all of the components. That will have to wait for another day or two.

Anyhow, I'm very happy with the result, considering that this is my first PCB. I also want to mention that I'm very pleased with the quick service of ITEAD for the manufacturing (not so with DHL who delivered the boards, but that is another story).

In the meantime I have some more work to do and wish you all a merry Christmas! As a present I will leave you with two photos of the actual boards.