Star Of The Ball – Part 2
Well, that went quickly! I’m now at T-2 days until the night of the ball, and thankfully, all my eBay bits have arrived in time! (Aside from a mild nuisance of some wrongly delivered NPN transistors, more on that later…) Here’s what my test bench looked like yesterday, with some basic debugging going on.
As of this evening, I’ve gotten the controller PCB built and working, with a nRF24L01+ radio for user interaction, and I’ve prototyped a pretty solid menu structure for controlling the pattern and brightness. I say prototyped, as I’ve hit a little math (I think!) snag when moving the code over from my Atmega2560 dev platform, to the 328p-based controller, but I hope to have cracked it by tomorrow.
While it’s not as bright as a star, this dress will certainly be eye-catching!
I had originally been worried about the amount of power being passed through the power transistors (~20W/ea), but after having been shipped some NPN (no good for this application!) rather than some PNP transistors, I was forced to salvage some nice FET’s from the scrap bin, and they are cool to the touch. Below are a few photos to give an idea of the construction of the controller. The circuit is about as simple as it gets, using textbook wiring found in most common examples for FET and nRF24L01+ applications.
As of tomorrow, all that’s left is to grab some of my pre-defined RGB routines from some other projects, fix that nasty roll-over bug in the code, or at least work around it, finish the battery wiring, and implement a UVLO lockout in the code, in order to prevent any funny business with the Li-Ion batteries. Then a few beers in the evening with my friend as we mount the LED’s in place. Pretty rushed, but you know, I think this might actually work ; o)