My dynamo lights

Having at last discovered how to post pictures at CPF I thought I'd show off a few dynamo lights I've been building. There's an evolutionary process in here somewhere although I'm not sure where exactly it's heading.

The first light I'll show you just uses a section of Hammond case, chosen because I thought I could shoe-horn in 3 of DX's 8 degree optics and because I could put all the guts onto a bit of veroboard held by the cases internal sidewall slots. I used Martin's simple un-boosted standlight circuit with Bandgap's diode + bleed resistor arrangement (see the Standlight Thread for details). I ended up using only 2 leds and optics because I couldn't get the 3-led standlight circuit to work despite the best efforts of CPF friends.

Here's the light:

...and underneath and rear:

The verdict? Two XR-Es with cheap DX optics are perfectly adequate and should satisfy anyone. Right?

Wrong! Unfortunately, in this age of excess (and lovely dynamos), one must always have more....

Rear again:

...and on the bike:

Dual switches are on-off and low-high power. Boards are Cutter XR-E MR-11 triples. Rear socket is for a top-secret tail-light project... Optics are the narrow 3-Ns. Take it from me - one of these dynamo-driven triples is plenty for average speeds! With two, you have to pedal too fast (for an old bloke anyway).

Lesson for the day? Excess is everything!


Here's the evolutionary record minus a few mutants and deadends:


Waddyer reckon? Is the gene pool exhausted or is it going somewhere?

Sam

Gota love them triples... Good job. So do they run straight from the dynamo, no batteries?

PapaLumen saith "Gota love them triples... Good job. So do they run straight from the dynamo, no batteries?

No batteries! Just a big smoothing cap. in the 6-packer. I made a big mistake with this light! I hardly pedal fast enough (at 18-20km/h) to get the whole lot up to max output - I usually run it with just one engine engaged. Quite bright enough thankyou!

I guess it may be easier to get max. light with more efficient LEDs - maybe the XP-Gs - but I knew nothing about such things when I built this. Would I get max. brightness at lower speeds with the XP-G?

Sam.

Fantastic post Sam! I enjoy seeing how these things evolve.
I'll do a similar one one day about a few generations of taillights.
BTW.....You need to tell us more about the secret tail light project!

Good stuff!

Come on ... don't tease us about the tail light!

Nice work Sam! They look so nice that you might have to worry about the risk of theft... something that has never been a concern for me.

Steve K.

Savvas said:

Would I get max. brightness at lower speeds with the XP-G?

Sam.

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you need a voltage doubler at low speed with a triple.

A nice triple's enough. Night riding the errand bike lightened of unessentials I have run the triple XP-G R-5 up to 32 kph, but mostly about 20-24 kph. I could ride just it or just the helmet light (battery) triple XP-G. It has more light than twin XM-L's at 700 mA but not quite as much as they have at 1.4 A.

Nice collection. Not sure I want to show my ghetto engineered first light. Its only good feature was it induced me to build the XP-G lights because it was so poor.

BrianMc said:

A nice triple's enough. Night riding the errand bike lightened of unessentials I have run the triple XP-G R-5 up to 32 kph, but mostly about 20-24 kph. I could ride just it or just the helmet light (battery) triple XP-G. It has more light than twin XM-L's at 700 mA but not quite as much as they have at 1.4 A.

Nice collection. Not sure I want to show my ghetto engineered first light. Its only good feature was it induced me to build the XP-G lights because it was so poor.

Click to expand...

Great to know what my first will look like.

Hi Folks,
Here are some pics of the latest effort. This light was intended as a 'running' light - on all of the time as per Steve K's credo. I think it makes a lot of sense for a commuter bike. It just consists of a bit of channel - about 40mm X 20mm - and some angle for the mounting plate. Open at the side in an attempt to promote off-axis visibility. It's not quite finished as I need to chop a bit out of the rear of the top plate so I can fit it neatly in front of the stem. It'll probably bolt to the bars with a Cateye type clamp at each of the rear corners.

It is just made up of 2 x XR-E leds with Ledil Rocket smooth spots (I had to chop the bases a bit of course), a 4700uf cap and a small rectifier chip.The latter are mounted on a small bit of veroboard jammed into a length of chip-case found at the local recycler. The XR-Es are fastened with double-sided heat transfer tape and 3mm nylon screws from Jaycar. Everything's rather untidily sealed up with hot glue. I was going to use epoxy but I remembered how last time I did, capillary action saw it creep into the lenses and rather spoil the beam. I should have tried silicon (dripped into bottle top rings around the bases) but I ran out of patience!

Eventually this will probably be teamed up in series with a 6 or 10 led rear light, also 'on' all the time. It is of course very bright, even just on the test-rig. Quite bright enough for my sedate commuting pace anyway. The beams look to be very smooth. Not as intense and long-reaching perhaps in the centres as the cheaper encapsulated 8 degree 'Cree' optics from DX are but very nice in their own way! And of course there's the off-axis spill as well...

Pictures:

Hot glue lacks artistic refinement!

...but the Rockets look nice!

Recycled chip case is great stuff - lots of different profiles. Top plate yet to be profiles and drilled.

It's 'hand made'!

Bright enough from walking pace.

Off-axis vis. looks promising.

Test rig - Velocity rim of course!

Here are some potential enclosures I'm playing with.

The aluminium 'Dariel' pots in front (from the local kitchen shop) are prospective housings for a 'cheap' dyno light I'm working up for a friend. I favour the slightly larger one on the left which has a nice rolled edge but the other is made of much thicker material. Both will fit an MR-16 triple and lens with maybe a bit of split clear plastic tube or trim around the edge to fill in the 3-4mm gap. The nicely made housing at the rear was knocked up by a local fitter in the days of halogen downlights. It's also on the drawing board for installation of an MR-16 triple dynolight.

When the 'Off-Axis Twin' is up and running I'll try to get some approach pictures on the angle - should be interesting.

Sam.

Hi Sam,
Good one!
I'm looking forward to seeing the final outcome/pics.
The awareness of the need for increased visibility, especially from the side, is one of the great things thats come out of this forum (as is the awareness of the poor performance of many tail lights).
Running lights with a side (or side plus ahead) focus deserve exploration and it looke like you're going to post the "benchmark" model....beware we'll all be out to better your design.

I like those Rocket lenses too, and I agree that it's handy to use the limited sidespill light to improve visibility to the left and right. No point in wasting it by keeping it inside the light housing.

Steve K.

Steve K said:

...I agree that it's handy to use the limited sidespill light to improve visibility to the left and right. No point in wasting it by keeping it inside the light housing. Steve K.

Click to expand...

It sort of works with the Planet bike and PDW blinkies. With a 100+ lumen tail light it should be great at night. Suspect so-so in the day. But a double XM-L even at 1.4 A it just might to the trick. Side windows with epoxy lenses have been done by a Znomit.

I wonder if we could ask him to ride by a viseo camera in day and night shots to see how effective it is on his?

Here's another design that I found interesting and that looks like it might offer some off-axis visibility (more than spill that is): http://www.nueb.de/fahrrad/licht/mueller/

I found this design while researching the Gaggione TIR lens that Supernova seem to use in their E3 dynamo light. The acrylic tube that this chap uses would make a lot of sense for home building if it wasn't so hard to buy in small quantities. I now find myself scouring the shelves in the supermarket and hardware looking for products in nice clear tubes...

Sam.

It must be a case of great minds thinking alike.
That design has excellent off axis visibility.
I built a taillight like that (without seeing your link or any other similar light) about a year ago - see:
http://www.candlepowerforums.com/vb/...ild-new-lights!
The side visibility from this one is better than the "3 in 1" taillight in my earlier posts..
It would make a great "on road" headlight with heaps of side visibility and I must be very slow for not thinking of building one using that design.
Good find Sam!

Farnell Australia (now Element 14) have the Fischer 100 X 100 heatsink that was carved up for these lights. I have an account there so may get one in a few weeks and find a friendly machinist to turn up a couple of round bases as per the plans. However I suspect for a dynamo light a simple 5mm aluminium disk would do and the fins may be overkill. I guess it gives you a battery-backup option!
I note that Element 14 also have the 40mm square sinks featured in other pics at the site as well as a square 35mm one. Food for thought.

Sam.