For Toxic BBQ 13 (DEFCON 25), we returned to the OFBC to see if we could improve the design and add some needed table decorations.
The first step was to simplify the PCB creation. I created a new layout in Fritzing that reduced whitespace. It also moved off-board components like batteries and the LED modules to use JST connectors for easy installation and swapping. OSH Park did a great job with the PCBs. I was able to directly convert the Fritzing designs to printable format. Each board was less than 2 bucks by the time we finished. Never again will I make my own PCBs by hand.
Sparkfun supplied most of the same components for about 15 bucks per light. Here is an updated BoM for this case:
- Battery: 850mAh Lipo
- Switches: Hinge Lever Micro Limit Switch
- Mosfet: N-Channel 60V 30A
- Transistor: NPN Transistor
- Resistors: 100K and 3.5 Ohm Resistors
- Slide Switches (ensure pitch matches the PCB)
- LED: Cool White, Aluminum Backing
Next, we redesigned the case. Instead of a three piece design requiring glue to assemble, the two pieces would be a base and a lid with a logo. Everything could be screwed into designed posts and covered with the lid. It was a snap. Production was easier with Shapeways. However, this lead to had longer lead times that prevented us from delivering to the barbecue. The prototyping went well and matched the designs, but the mass printings were so delayed that they didn't arrive in time for the barbecue even with expedited shipping. The resin product looked much better than the filament-printed 1.0 model. The cost at 20 bucks or so each was not prohibitive, but it certainly wasn't mass-market ready.