Errors, and then some.

A project log for Team Ides: DC27 / da Bomb!

A wearable, hackable, blinky badge for Defcon27 featuring RGB leds, sound, BLE, games, and more!

John AdamsJohn Adams 02/20/2019 at 20:240 Comments

I spent most of yesterday doing financial projections for the badge and writing out the copy for our Kickstarter page. 

From that copy will come a two-minute script which I will orchestrate in Pro Tools, and then I'll shoot lots of product shots and B-Roll to fill in the timeline. 

It's coming along but I'm still working through ideas for the video. Maybe a 1940's newsreel or something campy would be fun given the "bomb" theme. Let's hope it doesn't bomb... 

Unfortunately, during all of this I heard back from Macrofab that C506 and R605 were wrong. Apparently we'd placed C506 on the wrong side of the board and the cap wouldn't fit. Because we're doing stereo audio this year we've got a set of large electrolytic caps to sort out all of the audio signals. They take up a lot of board space. 

As far as R605 goes, there was some confusing descriptions in the parts order. We're shooting for 0603 parts across the board this year to save space and money. On the 2017 board, we used mostly 1205 parts to make it easier to hand-solder. Now that we own a stereo microscope, I don't really care about size as much. But, R605 had a 0201 pad (doh) instead of an 0603 pad, and that ruined everything. 

Side note -- Did you know that a) it's next to impossible to get SMD electrolytics that are smaller than 35V (sure, there are some 16V caps out there but not much smaller) and that b) Most of the SMD aluminum electrolytics derate when they reach 60-70% of their voltage? It's no wonder that you can only get them at 16V. You've got to buy things that are 3x the supply voltage to make them work at all and maintain proper ESR.

You're also not allowed to replace your gerber files at Macrofab if the order has been started. This morning, I cancelled the prototype order and replaced it with new files. 

All I can say here is that I would much rather be catching these issues now instead of a month from now when the PCB comes back. 

Maybe I should be reading my own post-mortem from DC25 and reminding myself what not to do.

More updates as we have them.