In parts 1 and 2 of this series of blog posts, I shared how I design PCB's using CadSoftusa's Eagle PCB Design Software.


Having the design on screen is one thing, but holding an actual PCB in my hot little hands is quite another.


Screen Shot 2015-08-17 at 14.58.23.pngPCB.jpg



Although some PCB manufacturer's will take the .brd and .sch files, most prefer the gerber files. (This is a standardised format, in a similar way that pdf's are for documents).


For my previous boards, I have followed a tutorial I randomly found online - however, this time I followed Cadsoft's tutorial on making the gerbers - copied below: (Note, following these instructions meant the silkscreen (words) didn't turn out as I expected - I have added in the tutorial (in red) how to change this.)



"Generating Gerber Data with the CAM Processor

The same steps are usually required for each board whenever films and manufacturing data are generated. This process can be defined as a CAM Processor job.

The file, which can be found in the default subdirectory for CAM jobs, automates the output of the most common Extended Gerber data for double sided boards.

Please contact your board house to confirm which data are needed.

Load the job into the CAM Processor, either by doubleclicking the entry with the name in the Control Panel's tree view (CAM Jobs), or by clicking the CAM Processor icon in the Layout Editor window and selecting in the file dialog (File/Open/Job).


In case you have started the CAM processor from the Control Panel, load the board file demo3.brd: File/Open/Board and demo3.brd

Here is where I needed to change some bits to make the silkscreen look how I wanted:

Click the Silk Screen CMP tab, then click on 25 tNames to unhighlight it, and click on 27 tValues to highlight that instead.

Screen Shot 2015-09-09 at 18.11.53.png

Click the button Process Job. Now all the necessary files will be written into the directory where the board file is located.

The files have the following meanings:


demo3.cmp    Component side

demo3.sol Solder side
demo3.plc Silkscreen for component side Soldering mask for the component side

demo3.sts Soldering mask for the solder side

demo3.gpi Information file, not relevant here


The first five files need to be sent to your board manufacturer.

Generating Drill Data

Drilling data can be generated accordingly by using the job This job consists of one single step. The EXCELLON device generates a file that contains both drill data and drill table. The output file has the file extension .drd.

This file has also to be sent to your board manufacturer.
Further information can be found on the CAM Processor help pages and in the EAGLE manual. "


It is a good idea to check the gerbers before sending them off. (I didn't). I have now downloaded cuprum, which seems to work well. (Found via an Element14 search


I have been told (by @adamgreig) that is also very good, but I need more gerber files than is given in this tutorial to make it work.


After making the gerbers I then zipped the six files and sent them to my PCB manufacturer (Ragworm) who kindly checked them (but obviously not the silkscreen - how would they have known what I wanted?)

After getting the OK, I ordered some - and a couple of weeks later they arrived ...



I quickly soldered the components on. I discovered that the phototransistor has "knobbles" on its legs and so wouldn't go through the holes. I believe this has something to do with protecting it from heat transfer from soldering. I could have made the LED stick up the same amount for symmetry.

LED vs PhotoTransistor.png


The finished board does exactly what I wanted. The LED lights up if not in direct daylight (not near a window in the house) and goes out when it is near daylight. Now to wait for Halloween!



Do let me know how you'd use an "OnWhenDark" PCB - or if you have found this tutorial helpful. Also, if there are any bits you'd like clarifying, please just leave a comment below.