Designing good daytime rear commuter lights

[Savvas]

BrianMc,

I was playing again last night with the DX red MR-16 module on my dynamo. Very impressed by the amount of light produced. Then I took 1 what's cue and found a translucent white milk bottle top to put over it. Whoa! Fantastic light spread! Maybe half a ping pong ball would work better but this was pretty good.

However if I glue it on I'll block the ventilation holes around the front face. You've had these modules apart I think for your Marwi conversion. Can you tell me please if you thought the LED was effectively connected to the pressed aluminium shell?

Thanks,
Sam.

[BrianMc]

Credit goes to Pe2er, aka Erwin, as i asked him the best disassembly approach.

There are four leads, a pair each side of the LED if I remember right. and the back is thermal epoxied to the base. It can be freed, as Erwin has done. But from a thermal transfer point of view or vibration/drop point of view both of mine were fine.

The bike they were on is being rebuilt. I may mount them on another as I have not done night ride by's or away's, with them, the Turbos, or the Danger Zones. I need that base line to pursue ideas.

[znomit]

I was playing again last night with the DX red MR-16 module on my dynamo. Very impressed by the amount of light produced. Then I took 1 what's cue and found a translucent white milk bottle top to put over it. Whoa! Fantastic light spread! Maybe half a ping pong ball would work better but this was pretty good.

I've played some ping pong
http://forums.mtbr.com/showthread.ph...83#post6431483

[BrianMc]

Up the resolution and you up the file size. I am not sure how big I can go on the host site. So I submit a 'short' with a stop line/far lane distance, stop line/near lane distance and two more distant passes leaving out the intermediate ones. To speed matters, I am not converting and editing the file: no sound, no titles. I have not edited the ride away video, but trust me, you can SEE these lights at 1/4 mile from behind and that's with them splayed out ot 45 degrees (approx) to each side. The camera is zoomed in but it can't adjust sensitivity as we do, nor concentrate on the center field of view. There is an interesting 'massing effect as the helmet light, Marwis, and rack light fuse intoa throbbing red mass. Nice WTFudge? factor.

The DangerZones' lower output, 45 degree mounting and wider spread took them out of the league wrt the Turbos and Radbot 1000s. Then I discovered I had not swapped in fresh cells, so the jury is reconvened, though it doesn't look good for them. The Turbo on the helmet is doing a great job rearward and not too shabby to the side at night. I did the ride by with a Turbo on the helmet and rear of the rack, and two Radbot 1000's canted out at 45 degrees, and the Marwi/DX red MR16 DIY with the 'bubble lenses'. The Helmet light is on 1 amp and has an amber hood to catch a halo of light I got by letting wide angle output from one LED out leaving a gap between the lens barrel and the LED. Looks like I should do that with all three as it is barely noticeble in daylight and could use more at night, too. The bubble lenses, are a mostly translucent 'ping-pong ball' idea. (here). Really twin, smaller, 'Aftablastas'.

http://img580.imageshack.us/img580/4851/npj.mp4

I have close and one lane away without the lights on the truck, too. The camera doesn't do reflective surfaces justice relative to the human eye. That said, I was not travelling fast by bike standards, I am guessing in the 10-14 mph range. A driver should be turning to look for traffic and then will see the bike approaching and get more of a head-on view. If he looked right first, and you ride by as he is looking left it's like: 'Whoa!' Given those reflective wall tires light up at home, I have to hope that the camera is doing them and the rest of the reflective material a grave injustice this close in. It may be with this much street lighting ambient light is swamping them out. Not sure where I can pull this off that does not have overhead lighting. With no high beam, the ANSI vest only comes into play close in or under a bright street light.

I think the second last and last passes show the bubble lights shining like a car brakelight and the rest of the lighting side on is AWOL pretty much. Unless I am mistaken, there isn't an appraoch angle you cant't see them. In fact, if seeing the bike riding away, they get brighter as the straight on beam comes to bear. At the same angle approaching, both the helmet and dyno headlights serve the same purpose well. That is without turning the helmet light to bear and looking at the camera/'dirver' as I passed.

So I think the bubbles tamed the rear straight on for night use and provide excellent side visibility. Maybe I need triple XP-Es on a low current setting at night and wide open in the day and the driver to provide flashing mode(s).

Can you SEE me now? (Lame Verizon joke.)


Brian

[BrianMc]

Riding away:

http://img199.imageshack.us/img199/3036/ncw.mp4

DIY bubble lights at 45 degrees, Dangerzones (almost discharged, forgot) 45 degrees on stays, Turbo on helmet, Radbot 1000 in second blink mode. The camera is maybe half as sensitive even zoomed like this as the human eye, as there was enough light to ride or drive by without using vehicle lights. Those circles of light and the field of light are not seen even though the camera is on night mode and +2 stops.

Night conspicuity from behind is very high and looks like a police car turned on its side except no flashing blue and whites. THAT should be unusual enough to punch through expected light arrangements.

I did not realize the camera loses its zoom each off/on so a ride with just the DIY's at 45 degrees and straight back will take another attempt.

[1 what]

Hi Sam, re your post #179 and my post #177:
As I’ve said elsewhere (more than once) getting enough light out the back of a bike light at night is no longer a problem. What remains a problem is getting enough light out the sides and towards the front to let motorists register the fact that there is something there…and hopefully they will realize that the “something” is a bike with the speed, vulnerability and other characteristics of a bike and not another fast moving car.

One variable re side/front visibility is the size of the light as distinct from the brightness.

Most lights have a smaller area of side visibility than rear visibility.

I wanted to make a light with more visibility from the side and oblique front than from the back. To do this I wanted the same brightness all around but larger display area at the sides and as much “wrap around” to the front as possible.

Hence the idea of using a reasonable sized (60mm) circular body and trying to light it as evenly as possible by bouncing light around inside it (internal reflections plus silvered “floor”).

Add to this the option of having a much brighter daytime mode for the benefit of motorists approaching from the rear when the cyclist is riding into the sun. This could be achieved by a “focused hi intensity light field” out the back with minimal need for side illumination.

The practical issue was how to achieve all this as efficiently as possible since it is not cool or fun to tow a couple of high capacity car batteries around behind the bike.



The “Light Pipe”

The job of the light pipe was to push most of the light from the LED out the back of the taillight in “Day-time” mode.

I started with a solid acrylic pipe which worked reasonably in transferring light out the back but gave little diffusion to the sides so did not achieve decent all round (to the sides) light diffusion for side illumination in night time mode.

This photo of the light source without any light pipe illustrates the problem. It was worse with a solid light guide in place.


If I sanded (frosted) the outside of the pipe to increase diffusion it lost its’ “out the back” efficiency (ie it was no longer an efficient light guide). I solved this problem by using hollow tube with smooth highly reflective internal surface and sanded (frosted) external surface – thus the light that escaped through the sides was diffused into the outer chamber to illuminate the sides and front of the outer chamber while most of the light went “out the back” in day-time mode.



I tried a 70mm focal length lens at the outlet but did not like the fact that it made the alignment of the taillight more critical even though it increased light intensity. I felt it was bright enough without it.

The “Rear Diffuser”.

As you can see from the following photo the rear diffuser is opened or closed to set day-time or night-time mode and its main job is to stop motorists from being blinded at night.


In night-time mode with the rear diffuser closed there are increased internal reflections/diffusion and a reduction in out the back light so as not to blind oncoming motorists. I adjusted the “opaqueness” of the rear diffuser with layers of mid-grey photographic negative.

I also increased the even distribution (bounce) of light within the light guide by fitting internal front and back 2mm plain acrylic lenses – these served the additional purpose of sealing the hollow pipe and keeping out road dirt and moisture. You can see the back lens just inside the Fenix diffuser in the “Day Mode-Night Mode picture.


This is how the day-time brightness compares with the brake light on my “mighty Mazda”.
In the real world it’s very visible at 200-300 yards.



I hope this gives a bit better overview of how it works.

[Savvas]

Brilliant, brilliant, brilliant!!! I hope you don't mind some imitation! I have some 55mm tubing here...

Mmm - how about one at the front as well - then you'd really get the 'Enterprise' effect!

Sam

[1 what]

Thanks Sam.
Go right ahead - The only condition is that you improve on the design - there is always a better way of doing things.
The fun part was drilling the hole through the side of the big pipe in order for the light guide to stick out the back. I abandoned acrylic and went for PVC because it was much easier to work (and less expensive). It was also slightly opaque and lit up rather than simply passing light.
I think you should build the TIR optics mounted in clear acrylic tube for the front lights (as described in your post elsewhere). They would give excellent side visibility at the front.

Re posts #184-5:
Very nice videos Brian.
Yes - I think we can all see you now.
The sad thing is that these taillights are a world away from what I see on the road each morning.

Any support for the idea that we invite 4Sevens or one of the other hi quality (but lowish cost) manufactures to manufacture a light with our ideas (as a public service to fellow cyclists?) I doubt that I own the intellectual property once I publish it on CPF.

[BrianMc]

I What - Thanks. Glad you enjoyed the videos. Thanks for the time spent setting up the pics in your post. Very nicely done. You have me thinking again and that is dangerous - at least to my bank account.

The amount of translucence is pretty critical doing this sort of thing. A white 35 mm film canister is not transparent enough, a clear tube is too transparent. The bubbles I used are caulk tube caps with a slight milkiness. I was afraid it woud be too transparent but it is close to spot-on. Serendipity works.

As to manufacturers, sometimes you need to have a trendsetter show the way. I suspect that Planet Bike would not be the first in with a sub $40 AA version, (I see no reason at this size to do AAA). Dinotte seems married to their tubular housings but maybe a Li-ion, Usb-port-rechargeable cell on board, and the lens out the back might work. Their 140R (and they had a 4000R) would be enough power and have remote Li-ion packs. With a white power LED: a front side marker light too. LiteFlux seems to be pretty innovative, but maybe as a small company, they have their hands full getting the RedZone 4 stateside and the white version out down under. We haven't really seen the RedZone in play using the wide angle of the lensless LEDs. So maybe we already have a high-end ($100-150) offering using a different approach.

An interesting front road light can be seen here. The Roxim RX5 Premium (4 AA's) has two 1/4 watt? LEDs that widen the output near the bike. No question they light us a wide near field path. Too bad they did not show what these light s look like to drivers head -on, and cross wise. The RS3 model (twin AA's) is briefly used as a comparison has less power but is a nice light light. Be a superb backup, 'get-me-back-home' light. There might be enough side output at night. In the day, a snap over diffuser lens like your idea 1 What, might be the ticket.

I know this is rear commuter light thread, but I OK'd this with the OP.

Brian

[Savvas]

1 what,

Is the 60mm PVC pipe a hard plastic (like acrylic) of is it the slightly flexible pvc. I imagine the former but thought I should ask...

Where did you get the 60mm pvc BTW?

ta,
Sam.

[1 what]

Hi Sam,
The PVC is non-flexible.
I picked it up as a short (15cm) scrap piece from a Brisbane firm called Industrial Plastics.
http://www.industrialplastics.com.au/default.htm
I suspect you could locate a source closer to home.
If you cant send me a PM.

[Leiothrix]

I've just read through this thread and have ordered a bunch of bits from DX & ebay to have a go at making one myself.

I figure 3x 1W red cree's in a transparent plastic box. One facing straight back and the other two angled back 60* on either side. It should give plenty of sideways illumination as the whole box will light up.

I'll have the middle one blinking (or maybe the two outer ones?) and the rest on constant. I've ordered a few lenses and diffusers to play around with too.

Not having built anything with high power LEDs before I am a bit worried about heat though. Something to play with anyway.

I've also ordered some reflective tape. I figure some tape on the front forks and stem, and rear stays will help with visibility (especially from the side) at night as well.

The hardest part is of course waiting for the goods to show up from DX. Cheap they are, fast they're not.

[1 what]

Hi Leiothrix,
Welcome to CPF.
You sound like you're set to have some fun - Please keep us up to date with your adventures in the land of better taillights.
The reflective tape works very well especially from the side if you put it down your frame. It also works well on wheel rims as long as you have disc brakes.
About your concerns re heat:
If the LEDs are enclosed within a box you'll need some way to shed the heat if you drive them anywhere near full power.
Most of us mount them on the "outside" so they can be in the airstream or connect them to a heatsink on the outside.
Remember heat kills LEDs very quickly and many of us know this from (sometimes expensive) experience.
You don't need dedicated expensive LED heatsinks - inexpensive general purpose ones work just as well.
Once again - have fun!

[mrbubbles]

This is what I have.










A simple top cap with a hole in the middle.

[Leiothrix]

Thanks 1 what. I was planning on mounting them on some ali bar, because it's easy to bend. I won't be driving them at full power, but I suppose I'll figure out how hot they get when I do it.

I have one of those red DX torches above as well as the five mode drop-in for it. It's nice and bright but I didn't like that it is too focused and the blink rate is seizure-inducing. It looks like you've fixed the diffusion issue, but I want a blinky that's a bit slower.

That and building it yourself is fun

[darkmilk]

The ultrafire and DX red dropin looks a lot like what I'm running, mounted to the carrier in a similar way, and I'm very happy with it.

But, I have a wide-angle elliptic TIR in it instead, the sort where shining it on a wall projects a line. This makes it really bright from well over 45 degrees each side, without a lot of light wasted up or down. It drops right off toward the outer edges close to 90 degrees though, better side visibility would be nice. The optic used to be a bigger one, that I have ground down to fit the head and polished. (dremel )

I also upgraded the DX module with a new red cree from Cutter, which makes it quite a bit brighter too. Now I run it on steady medium mode most of the time, and low is heaps at night. The new high is extreme and would really only be needed for sunset/sunrise or fog, and the flashing is just too obnoxious. (every street sign, reflector and numberplate for about a mile behind me flashes in my mirror if I do that )

[Savvas]

I see that Philips have come out with a dynamo driven rear tail light to complement their Saferide D front light. Don't know how to post the link in a manageable form I'm afraid but it's all at the Philips facebook page.
Savvas.

[1 what]

I've been a bit busy with "real world" events of late but have snatched a few minutes to continue to develop the better taillight concept.
I've been exploring colour change plus movement (within the light) to cut through the overload of stimuli that drivers have to live with.
If you pretend that the colours in the following video are yellow and red and therefore probably technically illegal as a taillight in some countries do you think it would catch your attention?
Hopefully I'll have the finished product on the bike within a couple of weeks.
http://img713.imageshack.us/img713/9276/t9b.mp4

[BrianMc]

^^ Most countries allow yellow for turn signals and 4-way flashers, and bikes often don't have to follow lighting specs for vehicles as strictly. However blue is often forbidden, and flashing lights in many European countries. It would be wise, if your lights are legal but questionable, to carry a copy of the code. Some officers lie to enforce the code they think is in place. ;(

Food for thought on this side/rear visibility thing:

1500 lumen headlights with side lights:


800 lumen Helmet head lamp with side lights:


Pivot mount Turbo on helmet :
[URL=http://imageshack.us/photo/my-images/20/photo0348v.jpg/]



45 degree mounted Red Zone 4's :


& 2 Spokelits on the front wheel (backside shown):



The dark road test. Camera at wide angle night, +2 exposure, 25 feet from road, giving about what a pedestrian or a driver with no lights would see at 50 feet. The right angles off simulating a driver with his head turned to look at an approaching bike, the left is blocked by a tree simulating a parked truck, building, or surprisingly, a tree blocking the view to the bike, one mailbox is strategic in the view blocking the sight line to the bike as a passing car might. The last bit passing the camera is like a right hook in countries where they drive on the right, flip it in your mind to think of a left hook elsewhere.

http://img402.imageshack.us/img402/521/5cd.mp4


The spokelits did much better than expected. Only 7 lumens out of the 'lens' about half of the old Superflash after 8 hours or so. Coin cell batteries last 20-25 hours on steady. Flashing on the wheels did not work with my test of the Red Zones, so I didn't bother. The cells can be ordered in lots of 5 or more for less than $1 a pair.

Learned;
1. The wheel shows up early in surprise approaches and the spokelits did well in identification.
2. The radioactive green is a visual surprise - until every bike has them anyway.
3. The Red Zones,mounted like that, show up much earlier than I'd hoped. Nice surprise, there.
4. The spill light of the headlights used for side marking is visible further past than I'd even hoped.
5. The total package is good: high and low,front, back, and sides. A truck blocking the sight line will make me a ninja, still, though.

Thoughts: The bike appears/disappears over a knoll to the right, but I think a power tail light on solid (which I have would still help. Definitely along fast roads or in daylight. There are frame wrap lights, but they are $25 (4 spokelits from some sources) and don't do anything that the spokelits don't, plus they can interfere with pumps, water bottles and things.

The performance of the lens-less 200 lumens each Red Zones is amazing. Nice wash of rear of bike and road. Great wide angle aspect. Makes you wonder about Leopold Porkstacker's light:



84, LED:http://www.ebay.com/itm/1PCS-10W-HIG...item439f3027cb

Two at a 45 degree angle with a driver to offer levels and flash: good compared to Dinotte 400's which have little side throw and concentrate the beam more. I thought 2x1 watt and 200 lumens was a lot. With 10 W spread over 180 degrees not 30, the peak intensity won't differ much, but the spread will. Saves all that messing about for a 180 + degree lens.

PS: if you want to see 500 lumens in action, try here. $200 and some side visibility.

BrianMc

[kenwood96]

I have a front magicshine xml light on a 5000mah 2cell lipo
and for the back 2 bare red emitters on a piece of folded aluminium, epoxied in for waterproofness...

the backlight runs straight from my hubdynamo without fancy regulators or drivers. MEGABRIGHT with 120° lightning!

[BrianMc]

....and for the back 2 bare red emitters on a piece of folded aluminium, epoxied in for waterproofness...
the backlight runs straight from my hubdynamo without fancy regulators or drivers. MEGABRIGHT with 120° lightning!

Yes, my next project a dyno tail light pair for the errand bike derived the reflector/bubble lights, testing a flare" lens (mostly horizontal), and no lens like the Red Zone 4s. I am impressed with drivers around the RZ4s (see the RedZone thread.) Nice to know that it isn't such a crazy idea.

BrianMc

[kenwood96]

I used some optics before too, My conclusion was that without optics, they were far better to spot in all directions and really eyepiercing!

[BrianMc]

Yes, my next project a dyno tail light pair for the errand bike derived the reflector/bubble lights, testing a flare" lens (mostly horizontal), and no lens like the Red Zone 4s. BrianMc

A broken cold solder joint on the DX driver (not the best quality) of the MR16 red spot bulb modified to fit MR11 housing, in one unit shown in this post. My excuse to take the reflectors out of both. I test rode the reflector-less lights with these bubble lenses and made videos but need to redo them to post here. Good enough to tell me what I wanted to know. The 1 Watt Luxeons are as bright as the 45 degree angle of the RZ4's, at slightly off axis, brighter than the narrow beam Turbo or HotShot. The paired lights looked like one big light and they showed at about 30 degrees from head-on, for about 300 degrees. Flare lens? They don't got no flare lens! They don't need no steenking flare lens! I need to see how they do at a distance. Considering they are the same output as a single RZ4, they were amazingly bright at 1/8 of a mile.

BrianMc

[BrianMc]

The reflector-less lights:



On (Single red Zone 4 between and lower:



Side view:



Angle view:



They are about as bright as my car's tail lights over about 170 degrees where you can see the LEDs.

BrianMc

[Savvas]

Hi Friends,
Found this at the DX site and just received today. A small 30mm (approx) diam mpcb with 6 X 1W red leds on boards.
Specs (from the DX page): SKU 94083
High power red light 6-LED emitter
- Voltage: 6~8V
- Power: 6 x 1W
- Current: 700mA
- Luminous flux: 110~120LM
From the specs I assume this is a 3S2P arrangement. I thought it would be worth trying with the dynamo, a bridge and a simple diffuser as a running light. I couldn't find a dedicated lens but there may be one at DX somewhere. There's a 4 led/4W/90lumen/4-5V version as well.
I'll report results!
Savvas.

[1 what]

Hi Guys,
I'm still following this thread but have been very busy over the last few months.
Brian - I'm impressed by your ongoing enthusiasm. I agree that some of these DX modules are bright! and maybe specific lenses aren't all that necessary.
It's more the angle of view and side on visibility.
Savvas - interesting find - why do you need optics? How about mounting it in an acrylic tube 6 or more cm long so you get good side visibility. There will be more than enough light going out the back and heaps directed to the sides of the tube.
I've got a new taillight to replace "The Enterprize" and will post details in the next few days when I finish putting all the photos etc together.

[BrianMc]

....Found this ... small 30mm (approx) diam mpcb with 6 X 1W red leds on boards.
Specs (from the DX page): SKU 94083 High power red light 6-LED emitter - Voltage: 6~8V, -Power: 6 x 1W, - Current: 700mA,- Luminous flux: 110~120LM
From the specs I assume this is a 3S2P arrangement. I thought it would be worth trying with the dynamo, a bridge and a simple diffuser as a running light. I couldn't find a dedicated lens but there may be one at DX somewhere. There's a 4 led/4W/90lumen/4-5V version as well. I'll report results!
Savvas.

Interesting and puzzling.

First output: The old '1 watt' spot MR16 bulbs I cannibalized for my lights test as about 100 lumen with my crude integrating sphere. That is close compared to the Red Zone 4's at half power. The 'one watt' led in the Turbo with fresh cells showed 90-100 lumens for a few seconds, too. There is a new XP-E Red rated 72 lumens at 350 mA, and 130 at 700 mA (1.6 W). If only 120 lumens total, that is 20 lumens per watt. The Luxeon is about 70 lumens per watt at 700 mA, and the XP-E Red is about 80. If 120 lumens each die, that is 150% of the best CREE. I don't think so.

Second resistance: Red power LEDs are typically around 2.1-2.5 Volts Vf at max current of 700mA. The Luxeon in my light s is actually about 1.4 W at 700 mA. A true 1 watt at 700 mA would be about 1.4 Volt Vf. Six in series would be 8.4 Volts. 3S2P only 2.1 Volt. So with approximately 6-8 volts to drive the array, it looks like they have a very low Vf for red LEDs and maybe a hair under 1 watt each giving an 8 volt max in series.

So we hope you will be pleasantly surprised.

BrianMc

[1 what]

As promised my new improved taillight.
As much as I like my light described in post 177 and 186 I’ve continued to think about the issue of attracting the attention of other vehicle drivers (so that they might “see us” and not run over us).
Brian, Savvas and others have written here and in other posts about the perceptual challengers involved in cutting through an overload of fatigue and visual data and I agree with almost all that has been said. The question is “how do we safely make them aware that there is a smaller, vulnerable and slower moving vehicle hidden in the dark”?
Brighter lights? Flashing lights? Bigger lights?
Then I thought….How about lights that change colour and change size….That’s not something you see every time you drive. That might register and attract attention.
Therefore I present for discussion the yellow/red size changing light. From the rear it simply flashes yellow and red but from the side (where most danger lurks) its’ size changes with the red light being twice the size of the yellow light.




In order to attract maximum attention from the side it is also larger than its predecessor.




Summary of the build:



Like its predecessor it has a Fenix diffuser on the tail so that it can be diffused for night-time use and opened for full direct output brightness for day-time use as shown in the last photo of post 186.
The LEDs are driven at 750ma from an astable multivibe with a 3:1 Yellow:Red ratio.
It has good visibility from the oblique front of the bike both day and night.

[BrianMc]

Nice 'out-of-the-box' thinking,1 what

Starship Enterprise & Jedi Light saber. I sense a theme. Then I guess mine look like small versions of Super Star Destroyer ion drives.

So 8 1/4 watt yellow LEDs in parallel for 63 mA, and one CREE XP-E Red, at 500 mA? What circuitry are you using for the switching?

I see you are using another diffuser. I don't think mine are as bright from just before 90 degrees to the forward angles, but I had a bright white door messing up the camera exposure. They should be close on lumens. So I may try a diffuser to increase that a bit since I can sacrifice some out the back output. I need to get a photo of the red wash off my lights to compare. Maybe with and without the diffuser.

Since I would like a light to use the battery pack(s) I have, I am thinking Bobblehat's flashlight & orange traffic wand vertical light in the backpack (on my back) idea, might combine well with this idea in a dedicated bike light. If you are using 500mA, a dyno version is feasible. That would be interesting for my other bike.

BrianMc

[1 what]

Thanks Brian.
Flasher/driver cct follows:


As you can see I built it the old fashioned way ...Microprocessors are for yuppies!
The battery pack is a 7.4V, 6000maH unit (ie 2S 2P)
Re the yellow LEDs. They are 0.3W and can be driven up to 100ma.
There are 9 of them in the light (2 at the top) in parallel and total drive current is about 666ma.
See;
Link to yellow LED:
http://besthongkong.com/product_info...roducts_id=534

The Cree is driven at the same level.