Step 10: PCB
The PCB is designed with mostly surface mount components. The board was made with inkjet transparencies on a photo positive board. This was my first surface mount board (both etch and assembly). I made a single sided board and used jumper wires for the bottom layer traces. The board was made with manufacture by Olimex in mind, so their 10mill rule check file was used when designing the board. Nothing is terribly small, but its certainly challenging. Everything was hand soldered using a 10 euro iron, stickie-tack, and a bright light. A magnifying glass was not needed.
The crystal was left as a surface mount component. The metal can is a distinctive looking element, and much more identifiable than a surface mount black-box. The prototype in the picture also uses a TO-92 voltage reference - the final PCB indicates a SOT-23 version that I didn't (yet) have on hand when I made the board.
Circuit and PCB are in the project archive (Cadsoft Eagle format - freeware version www.cadsoft.de ). Component placement can be seen in the PCB file. I also made a PDF with the top layer mirrored and copied several times. This should be ready for toner transfer or foto process.
Parts list (through hole)
32.768kHz Watch Crystal (0206 metal can)
Pin header -x4
Programming header - 6 pins
Parts list (surface mount)
1206 0.1uF capacitor
1206 33pf capacitors - x2
1206 LED (yellow, red, orange, etc) -x12
1206 Resistor - 4x56 ohms
1206 Resistor - 3x1Kohm
1206 Resistor - 3x10Kohm
1206 Resistor - 3x100Kohm
SOT-23 NPN transistor (100ma or more)
SOT-23 PNP transistor (general purpose)
SOT-23 NPN Darlington transistor (general purpose, hfe of ~10000)
SOT-23 MCP1525 Voltage Reference (2.5 volts)
Battery CR2032 3v lithium