Matthew Shen’s Status Report for 3/26

Towards the end of this past week, we finally received the parts for the PCB and the PCBs with stencils themselves. One of the tasks I did this week involved running tests to estimate the appropriate resistance needed to be put in series with the LEDs in order to run 100mA current through each diode. When I placed the order, I had ordered a resistor with a quarter the ohmage as the one used in the unit tests with just one LED at a time (since we are illuminating up to 4 100mA diodes at a time). Then, I ordered a couple of resistors with +/- 1.5 Ohms in case the PCB traces introduce more wire resistance than in our tests. Since we only have a couple of these high-power resistors to place, it shouldn’t be too much of a problem to desolder the resistor if it is too resistive or not enough. Additionally, while the LEDs we use are rated for 100mA of constant current, they can theoretically safely handle 1A of current so long as they are pulsed (which is our mode of operation). So, we should be able to run our diodes comfortably with all this in mind. Next week, we will begin soldering and frame assembly. I believe this puts us right on schedule to finish our project in time.