Milling a Circuit Board

For my first board, I wanted to create an analog circuit for a "breathing led". I borrowed this circuit from Eric Rosenthal's Basic Analog Circuits class. It pulses the LED off and on using capacitors and a 555 flasher chip. The potentiometer controls the speed of the pulsing. I would like to eventually try other variable resistors on this circuit.

circuit schematic

Though I originally thought the schematic would be the easiest part, it actually caused me the most grief. I had several errors, some of which I didn't notice until after I had milled the board.

For one, I put in my capacitors backwards, and I mis-wired my potentiometer. My first attempt I put a variable resistor symbol into my schematic that just didn't show up on the board design.

board design

In this image you can see the components outlined in white, the solder pads in green, the paths in blue, and the path for milling in pink.

first attempt at milling

My first attempt at milling missed 4 of the holes I needed for components. I also mis-wired the potentiometer, so the circuit did not work.

final board design

Here is the updated final board design.

milled and soldered board

And the milled and soldered board. Here I accidentally melted off the solder pad on one of my capacitors. The circuit blinked instead of breathed because the capacitor was not storing and releasing power to the LED.