First, here’s the videos:
I’ve chosen to use an Arduino in conjunction with a pair of Centipede Shields to drive all the incandescent indicators in the cockpit. Just between the BIT (Built In Test) and Master Caution Panels, there’s 74 channels of output required. In order to drive those lamps, I needed to build an intermediary board that could handle both the high voltage (most of the lamps in the F-15 are 28VDC) and the high current draw. While a LED can draw as little as 15 to 20mA, the typical lamps used in the F-15 can draw up to 150mA each!
The demo shows only 16 indicators being driven. Each indicator has two lamps behind it. The lamps installed are MS25237-387 and they draw 40mA@28VDC. 16 indicators eat up 1.28A – the whole panel can consume 3.12A if everything is lit at once.
The 16 channel output board was over-designed to make sure that I could drive high-current lamps as well as handle relays and the magnetically held toggle switches that are used in a few places in the cockpit. In order to drive relays or other coil-oriented loads, “back-emf” diodes will be used in order to prevent the over-voltage created by the collapsing magnetic field in the relay or solenoid from destroying the driver circuit for that channel.
The good news is that I’ll be resuming work on the F-15 very soon – this project has been sitting on the bench awaiting final test out, which is something I _finally_ was able to accomplish while being stuck at home due to medical problems.
Work on the new collimated display designs (not for the F-15 unfortunately!) will be interwoven with new work on the F-15. After planning, plotting, designing and re-designing, for the last 11+ years, things will advance quickly once work resumes!