Arrivals and mistakes

A project log for Lys Bright

A solar powered bright light

Ole Andreas UtstumoOle Andreas Utstumo 01/17/2016 at 13:110 Comments

The first time you're holding a PCB can be a little moment of truth. The PCB arrived less than a week ago, and without starting soldering, I could already see three mistakes that I'd made.

  1. The footprint for the LED is impossible to solder by hand. I need to borrow a reflow oven. I could have extended the anode and cathode pads outside the component, but instead I followed the datasheet's recommendation without thought.
  2. The soldering mask is exposing a thin line of the ground copper layer around each pad. Need to be careful here. We're talking maybe a tenth of a milimeter.
  3. The pin header and the barrel jack pads are covered by solder mask on the bottom side. It isn't entirely clear for me why they are like that in the final files of KiCad, but I can see the problem in 3D view...

Some lessons learnt here.

The Lumileds LXH7-FW50 <1A 5000K LED. At $1.5 - $2 each, they're a wee bit expensive.

My former colleague at who's working on improving ebike batteries sponsored the project with Samsung 29E li-ion cells (thanks, mate!) and the 5V 240mA solar cell was bought off a seller on AliExpress. I also bought some 4V (nominal) solar cells to see if they provide sufficient voltage at lower currents to charge the li-ion cells to 4.0V + the dropout of the "charger".