As mentioned, we’ve been hard at work on Prototype V5 of the Revolights bike lighting system. And while we’ve heard the call for more engineering updates, with new product specs moving forward it is important that we adhere to a strict balance between disclosure and exposure; for a variety of reasons.
 
Yet we take both this work, and your financial backing very seriously; so an update.
 
In an effort to stretch funds, we are performing a great deal of the prototyping by hand prior to involving manufacturers… electronics included. Here’s an example of a specific design challenge we encountered, worked through, and, via prototyping, overcame.
 
Design challenge: To allow the PV5 LED ring to house all components, the electronics needs to get, well, way small. At these mini sizes, designing the boards becomes a bit more complicated and soldering the chips onto the boards by hand also becomes tricky; like beyond under a microscope tricky (which we were already doing). After doing the board layout on the computer, the designs are sent to a company that specializes in “spinning” the blank board in a few days.

To populate the blank boards we receive I use a specific procedure which overcomes their miniature size… I solder paste the pads with a kapton film stencil and then re-flow using a skillet. Translation: I design a stencil, overlay the stencil onto the board (or PCB - printed circuit board), squeegee the paste that will solder the chips across the stencil, carefully place the chips on the boards with the microscope and tweezers, then (literally) cook them on a skillet I bought at Walmart. 

 
A bunch of design, trial, re-design, and re-trial later, the boards have now magically shrunk, and shrunk big time! When I say trial I’m speaking about running tests to evaluate specific chip functions and make sure the design is okay.
 
Check out this comparison picture:

The board directly next to the penny will be used in the V5 prototype. The larger board next to the V5 board is from the V3/V4 Prototypes, and the penny is just for reference. Notice the significant decrease in size. The board attached to the light and wires is also from the V5 Prototype.

… even better news; after a couple re-designs they work! Design challenge addressed.
- Kent