18jan14-update: project finished, see result here.
swiss road laws are changing. from january 1st, 2014 onwards, every vehicle on switzerland’s roads must have DRL – daylight running lights – when in motion. older vehicles without dedicated DRL can comply with this law by keeping their main lights on during daytime.
a TWIKE, obviously, doesn’t have any dedicated DRL and keeping the main lights on during daytime is not an option for most TWIKE pilots, including me: using 210-260W on just a bit of lighting just seems a tad wasteful and – in tw560’s case – will shave of 6-10 kms off my range.
I could go down the easy route: bring TW560 to my mechanic and tell him to fit one of the LED DLR’s he has been fitting on other TWIKEs. this involves drilling holes into the body and attaching ungainly after-market DLR’s to the TWIKE at various positions. yuk!
or… i could start drilling holes myself. some have already tried this – with varying degrees of attractiveness or practicality.
i am a TWIKE purist: if somehow possible, i want to avoid any changes to the outside or inside of the TWIKE. My TWIKE shall look as original as possible. Up until now, i have been able to keep TW560 in a very nice state in that regard.
So when i heard about this new mandatory requirement i was quite anxious to find a solution that did not need any additional parts being attached to the vehicle’s body.
where could such lights go? not many options are left: headlight and blinker enclosures. luckily the lights and blinkers used for the TWIKE are from cars that were available around 1985. After looking at the (extremely high) prices for replacement main lights and a very, very small selection of LED DRL’s, i decided the only place the DRL could be placed was in the blinker enclosures.
A visit to the interwebs yields some blinker enclosure-compatible LED-based solutions – all of them impractical for my needs.
direct light solutions will not work – the current blinker enclosure’s blinker bulb is mounted sideways – therefore i need a led product that emulates a bulb and is compatible to the bayonet bulb holder (yes, i am aware that i need to address the BAY-D issue!)
i found a suitable product from a line made for the ford tundra (where it is used for aesthetic reasons only):
with some changes to the cabling (TWIKE’s electronics are reversed and – is switched) and adapting the current bayonet connector to support 2 wires, i could drive the led’s correctly. no other internal changes necessary.
however, the current blinker covers are orange – this can be fixed very cheaply by buying clear blinker covers;
now, with all the bulb and enclosure issues out of the way, there is a next issue waiting to be solved:
whilst blinking or with the main lights on, i want the DRL to be off. whilst the latter requirement can be easily solved with a relay, turning off just one DRL whilst blinking and turning it back on after a specific time-out requires some logic.
logic of this sort can easily be purchased at a premium price e.g. €199 as a ready-to-use kit.
regular readers of this blog know that for me this isn’t an attractive option… let me do this on my own for a fraction of the price!
with my trusted arduino prototyping platform and just some few lines of code i can detect lights e.g. blinkers or main lights and react to these states accordingly:
in the base config / state, the DRL is on.
when either blinker is on, the corresponding DRL is off. this is a requirement since i want to ensure maximum visibility of my indicators. after a defined period, after the last detected blinker activity (currently 2500ms), the DRL is activated again.
when the hazard lights are on, neither DRL should be on.
when the main lights are on, the DRL should be off:
if you feel like watching this live (and hear me rambling on about it in swiss german) – be my guest 🙂
i will be ordering the required components in january and start assembling a pcb. in the meanwhile, i’ve created a mock-up image to show you what i think the solution should look like when it’s done.
if you would like to either have this too, or want to contribute – let me know.