Ducati 749/999 Tail Light

I finished this project a while ago, but never documented it. This is a taillight I made for my 749 before I sold it. I currently have a 999 so maybe I will make another one someday, but the 999 rarely changes out of it’s track/race clothes.

I was doing a lot of street riding when I made this, so I wanted something with better visibility than the (IMO) poor aftermarket replacement taillights. Specifically I was wanting to add a few high brightness pulses when the brake lights were turned on, but with a high enough frequency it would barely be noticeable. It catches your attention but isn’t really that obvious if you weren’t looking right at it. I’ve noticed recently that some fire trucks do this.
I’ve also been interested in a tail light with a light sensor so that the brightness can be ramped up during day time. Motorcycles need all the visibility they can get, but if the tail light gets too bright it will have the opposite effect at night and reduce visibility for people behind you.

While looking for an appropriate LED controller I ran across the PCA9952, which is a really nice piece that allows for up to 16 channels of LED strings at up to 40V each, with 8 bit PWM resolution selectable via I2C. I used this with an ATtiny45 that I had in my parts bin to run twelve total LED strings, 8 for brake and 4 for signals. This allowed me to use 5 LEDs per string so I didn’t need a boost converter to drive the LED strings.
Because I wanted a very low profile tailight that could fit in between the tail fairing and the exhaust I went with SMD side emitter LEDs this time. The acrylic is machined to allow the PCB to sit flat and the LEDs are countersunk into the face of the acrylic which couples the LEDs into the guide.

I had a new and improved version started based on a few issues I ran in to with the first one, but decided I wanted to sell the bike and get a race bike instead so the version 2 was shelved.

Machining the PCBs

Finished PCBs

Machining the acrylic

Side-emitting LEDs

Controller PCB populated

Final assembly (this version had wires for testing, next version would be all PCB)

Writing C code for the ATtiny45

Bench testing

Made a bracket to mount the silencers closer to the tail fairing

Test fitup

Finished

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Tuesday, April 4th, 2017 Automotive, Electronics

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