Dyno powered triple cutter R2

[znomit]

Got my triple R2 cutter kit up and running.

Last winter I made a couple of taskled driven lights, dual Q5 for the road and quad Q2 for the trails.
A new bike and a focus on longer distances meant I needed to build a new light head and I wanted to get away from batteries so I could run 400 lumens all night.

Luckily the lads at the LBS had a shimano 3n71 hub dyno wheel just waiting for me.
Martin has published a bunch of dynamo circuits for extracting a good amount of power from a dyno.
Cutter Electronics had just come out with the triple cree R2 and narrow optic which seemed perfect for the road.

From this I should get the same output as my old dual Q5 setup, the dyno outputs only 500mA.


The light head was built from the same aluminium section as my MTB light but a lot shorter. Its about 5x4.5x2cm.

The disk in there is a 8x25 filter from ledsupply. It will spread things out to give a little peripheral light, good for some of the fast downhills around here, I hope. Also should make me very visible to the cagers.
See what it does to the beamshot:

The light end were sealed with yellow epoxy(just add some food colouring into the mix) to give bright sidelighting. Combined with my white bar tape this gives the cockpit a warm glow.
For mounting I'm a big fan of keeping the bars free, so mounting over the brake calliper seemed like a good idea. Made a swoopy bracket for this.

From last years riding experience I knew I wanted around 200lumens for normal riding and as much as possible for downhills. The 3 R2s at 500mA should deliver around 400 lumens. Martin has a combination voltage doubler/rectifier circuit which halves the power when required. I went with his circuit 10, crammed into a small box that hides under the handlebar stem. Bottom switch selects high/low and I added a on/off switch at the side. Liberal amounts of silicon slathered everywhere for waterproofing. The electronics are pretty simple, 3 capacitors, two switches, 4 diodes and a resistor. I will always run with a backup light so a standlight wasn't needed.

The end result is quite tidy. Note beamshots are hard using the dyno, this one is upside down on the table, note one led has a wide spread.

Total weight of the light head, wires and control box is 175gms. The shimano 3n71 hub is 700gms. My old 12AA battery pack alone was around 400gms so I think the weight isn't significant.
The hub drag is 2w with the light off and should be around 6/10w low/high. An extra 10w has got to help the training! The power requirements go up with more LEDs, the triple seemed like a good balance of light and power.
I got a bloke to mill the head unit but it could have been done with hand tools, just not quite as tidy.
Total cost probably a bit over 100NZ$ (this is similar to 12AA NiMH and charger!) plus the wheel.

 

[trout]

That is one cool light idea I like the yellow sidelight idea

do you notice any drag when you switch on the lights.

and is there a way to use the dyno output to keep your backup light charged . or even to charge your cell phone or ipod.
on long touring trips

what a well green idea or would you be putting out too much CO2

 

[znomit]

The drag is a little noticeable, not huge but there. Its hard to pick the 5w drag difference between high and low. I'll probably end up on high most of the time when out training and low will be for oncoming traffic or when I'm in a hurry.
I ran the numbers here Bike speed and power calc and the 5w I'll be running most of the time will cost me less than half a kilometre per hour.
I dunno what the time lost for changing batteries adds up to, or the additional wind drag from a battery pack, or the fatigue from not having enough light, but I don't have to deal with these things!

A lot of the long distance crowd run hub dynos with 3w halogens, this is more like 20w on full...I could probably have managed with two leds but the extra drag is not significant, and the triple kit is very convenient.

I may have to cover some of the sides over with aluminium tape, think they might be too bright! Im laid up sick for a week or two so haven't been out for a proper long dark ride yet, just a few turns around the block at dusk. The light is visible on the road even under bright town streetlighting so should do well on the rural roads.

Theres a bunch of ideas around for charging batteries etc off the hubs, trip on over to the electronics page at bikeforums.net. On tour with minimal night riding AAs are the way to go I think.

 

[Martin]

Great how this came out, Tim. I like your clean handlebar approach. Hmm.. could the electronics fit INTO the stem ?

Thanks for sharing !

 

[znomit]

Martin thanks for your comments but thanks most for you circuit!

The capacitors etc would just squeeze into the steering stem but If I did that I would still need a switchbox mounted somewhere(with lots of wires in between) so I'm not sure I would gain anything.

 

[FrontRanger]

Great how this came out, Tim. I like your clean handlebar approach. Hmm.. could the electronics fit INTO the stem ?

Thanks for sharing !

Tim, thanks for showing us your work. It is commendable for its simplicity.

Regarding your mount, you might want to add some sort of rubber damper if you have not already done so. I've read reports that indicate that that mounting position is hard on the bracket, presumably because fork crown brackets are usually longer than bar-mounted ones. (Here is one page that mentions them.) I've done this with one such bracket on one of my bikes. I can't prove that it helps, since I don't have an identical copy of the bicycle without it, but it sure doesn't hurt. It may not be a danger at all with a lightweight light such as yours, but it's so easy and cheap (bit of an old tire tube will do it) that I thought I'd mention it.

Martin, I suppose there are some stems wide enough to fit one of your simpler circuits, but you might have trouble with access. I would never drill a hole in an aluminum stem, since failure in this part of the bicycle is not acceptable, but how else will you get the wires in and out? Some steel stems can tolerate such a hole, as evidenced by the existence of ones that use the stem as a cable-stop for the front brake. But the steel ones are narrower and less likely to accommodate those chunky capacitors.

 

[znomit]

Yeah the bracket probably is the weak point. Its radiused and I made it as wide as possible so will see how it goes. It wasn't super easy to bend in the vice(has a 15 degree bend to cancel for steering head angle) but fine tuning on the bike just required a moderate yank.

Last light I supported with a short mudguard, also kept the spray off. It was copper which is a little more bendy than Al I think. Way back I had a lumotec oval which mounted there, makes a lot of sense.

 

[ktronik]

:thumbsup:

great job as always!!!

:buddies: Dyno,Dyno Dyno!!:rock:

 

[SAVAGESAM]

Help me out here guys. I went to the Cutter website and those kits for bike riders (the ones that were around $99.00-$130.00) Are they for a complete kit? You just need to build it, or am I missing something (Like the LED?) Also can a first timer do this or is it science fiction and I better not waste my money?

 

[Steve K]

The Cutter optics and leds are pretty compact and convenient! do you have any measurements on the beam width? Or does Cutter have some data?

The packaging turned out well too. I see that I'm not the only person who had uneasy feelings about the mounting bracket. The wires should support the light when the bracket fails, so there is little risk of it going into the spokes. Even the bracket for one of B&M's Lumotec lights had a reputation from failing, and I think it was made of steel. You might check the bike shops, or Peter Jon White's web site in search of a robust bracket.

Again, nice work!

Steve K.

 

[znomit]

Its looks a bit over 10 degrees, I measured the widest part of the beam with the filter on and it was around 33 (hard to judge by eye). Beam picshere. I thought I had the narrow but reviewing my order it looks like the medium. Seeing that pic made me shout "omg look at the lumens" and thats when I figured I could throw in the wide optic (it'll degrade the mainbeam somewhat).
Carbon support bracket is on the drawing board in case this starts to bend. I could probably make a wider one out of the current stock, too. Mmmm carbon... might vibrate a bit though. The current one will droop before failure I think. Its longer than I would like but needs to clear the brake. I guess I could take the front brakes off, they just slow you down, right?

Savagesam:
Regarding cutter, yes the ordering can be a bit confusing.
I ordered the LEDs and optics seen in the first pic above, about 60 aussie dollars. The optic is only 7$ so might be an idea to get one of each if you're unsure(its the cutter 3 on their site). Note they came already wired. You can order the kit with the the taskled driver and a housing too if you want. Just search MR11 and all the options come up. You need to decide which driver you want which will be based on your battery choice.
Haven't seen a report on the housing build but it looks like a winner!
No its not science fiction...you need a little mechanical ability and a good soldering iron helps too.

 

[Martin]

..
Martin, I suppose there are some stems wide enough to fit one of your simpler circuits, but you might have trouble with access. I would never drill a hole in an aluminum stem, since failure in this part of the bicycle is not acceptable, but how else will you get the wires in and out?...

Indeed, I felt like drilling some holes there. The parts that I have appear to be heavily over-designed, made to withstand jumps... But you're right, shouldn't take a risk.

 

[znomit]

Been out for the first proper ride in the hills(been a bit sick the last two weeks), this thing is fantastic, lights the whole lane and 40m up the road. I use a nightrider minewtx2 (140lm) on the helmet and only really needed it for one dodgy downhill where the road is pretty rough. Never once felt like I was outrunning my lights.
Hard to do beam shots but here are a couple... 15 second exposures at F2.8
Red light is a cateye ld100 on helmet.

The sidelighting is pretty effective I think!

Other things noticed on the ride:
The under stem controls fall to hand very easily.
The drag is just perceptible turning the light on and off.
Mount seems to vibrate a bit, will keep an eye on it.

Have ordered some glow powder from glowinc so I might crack the head open and sprinkle that about when it arrives.

 

[nightrider]

Nice work! Those long exposure beamshots are cool. I never really thought about the difficulties of getting beamshots with a dynamo-powered light.

 

[znomit]

Added some glow in the dark powder for a semi standlight. Took off the wide filter too, will see how it goes.

Will redo the sides with gid epoxy once I figure out how to make it. :thinking:

 

[ktronik]

:twothumbs

top work... you da man...

K

 

[znomit]

Ktronic, thanks very much for the idea of using the glow powder.

I mixed up some powder and clear nail polish to paint the inside of the housing, kinda clumped and gummed up but worked.

The epoxy absorbs most of the short wavelength light needed to activate the phosphorescent powder (or maybe its the yellow colouring filtering out the blue) so I will try to coat the top of it.
The glowinc powder is amazing stuff.

 

[ktronik]

I think your latest light is TOPS~!!! but now it time to up the ante, kiwi mate!! :naughty:

What I want to see is a 'Sixer' so the same but using 2 of those cutter kits... you could do a total dyno or a dyno / battery powered version...

might hack up a 'sixer' myself... just a ugga for the commuter bike.

BTW nice trek!!! Same size I ride...:buddies:

K

 

[Martin]

Ktronic, thanks very much for the idea of using the glow powder.

I mixed up some powder and clear nail polish to paint the inside of the housing, kinda clumped and gummed up but worked.

The epoxy absorbs most of the short wavelength light needed to activate the phosphorescent powder (or maybe its the yellow colouring filtering out the blue) so I will try to coat the top of it.
The glowinc powder is amazing stuff.

Amazing idea to approach the standlight. What if we supercharge the glow powder with a UV LED ?

 

[znomit]

Ktronic
Light is in the sweet spot between Watts and Lumens. Don't want to pedal any harder and I can see all I want to see. Even a quad would be extravagant. But if I was going for more I'd use that 5 rebel MR11...

The only thing I would like is a really wide beam for fast twisty downhills(some crazy back roads around here). I only need it for very short periods (so run time of 20 min is fine). Im thinking a 9v powered dual setup with LEDs angled 40 degrees apart.

I will probably throw two cutter triples into my MTB light(or make another). The light is looking a little worse for wear after I cleaned the optics with spirits and I have about 4m of the aluminium. Shame not to use it

Martin, the UV is a very good idea (have a black light at work and it makes the GID blaze!) but probably excessive! I don't actually think the GID going to be bright enough but its interesting and fun to play with.