Dual Cree retrofit into East German dynamo/light unit

[syc]

I finally got the light built up using the simple standlight circuit referenced in the standlight circuits thread. I ended up using 2 silicon diodes in series for the voltage clamp once I tested it with higher voltages. With an 8V input, I'm seeing around 5V across the supercap.

Here's the front view of the retrofitted light:

You can just barely make out the emitters if you try. But it looks like any other piece of Soviet Era bicycle gear otherwise...

Here's what it looks like from another angle.

This light is going on my commuter/grocery getter, and I don't particularly want any of my parts to look especially desirable, given the rampant bike thievery in Berkeley/Oakland.

And here's the guts. I epoxied all the components to the board, because the dynamo/light unit gets a lot of vibration and I didn't want things rattling loose. The circuit board is also covered in electrical tape now to electrically isolate it from the light enclosure. My soldering is awful, I know, but I want to build a few lights that don't require high quality soldering before building something fancier.

The standlight works as advertised, and its pretty simple to construct this basic version. I will have to wait until after dark to test out how bright it is, but even in daylight you can see that the standlight LED is on.

Thanks to bandgap, Steve K, Alex Wetmore and all the other folks who contributed ideas to the standlight thread.

 

[Alex Wetmore]

I'd love to see photos of your beam. How does the reflector and lens on that old headlight work for you?

alex

 

[rala]

I'd love to see photos of your beam. How does the reflector and lens on that old headlight work for you?

alex

+1. Im curious at how the reflector/lens combo will affect the beam pattern of the crees'.

 

[syc]

In a word, the beam pattern is "Zebra". For some reason the optics setup a zebra stripe pattern with vertically alternating bright and dark stripes. I'll try to setup some beam shots tonight.

I may try to kludge up a replacement optic, but for my purposes, the current setup is actually adequate, and kind of fun.

The standlight runs for a long time as well, and is definitely bright enough to be seen. It might actually be bright enough to change a tire by if the positioning worked out.

 

[yellow]

the vertical "bars" at the front glass spread the emitted light,

if this is the actual setup, use optics, the usual 8 degree ones.
Without optics or reflectors led are totally useless (and the original one does not work now, the led are too far inside it)
looks like the 20 mm space is still there

the front glass will spread the two beams again and You might receive a nice, oval shape

 

[syc]

The optics finally arrived and I have put them into the light and have been using it for commuting for a few days now - with the 6x24 oval and a 6 degree RS on the LED's, the beam pattern is a lot better. Here's a few photos of the beam pattern, as well as a link to my flickr photostream with a few more photos, including the standlight after 2 minutes or so.

Beam pattern of the light and the standlight. Exposure is set to make the standlight look about what I saw, but results in overexposure of the main beam pattern.

Settings: ISO1600, F1.4, 1/15s - from just under 10' to the fence.

Here's the main beam, one stop lower exposure (1/30s instead of 1/15s).

I think you can see the oval beam pattern from the 6x24, but with the 6 degree spot basically providing boosting up the central hotspot.

Here's the dynamo light mounted on the light bracket (had to use the oddball mount combination to get the position and beam angle I wanted.)

There's a few more photos in the Flickr photoset for this project.

 

[DocD]

very nice, old skool :twothumbs with a modern upgrade very

 

[nintendo64]

Nice, im so jealous!!

ive just ordered a Cree R2 drop in from DX, got some 1N4007 diodes and capacitor so i can do a similar project.

 

[Buck91]

That looks fantastic! Would you mind taking a shot of how you mounted the optics inside? I've been wanting to set up a dynolight for the bar bike, but have not found any way to overcome the bizzare beam patterns...

 

[syc]

I actually don't want to go and disassemble the headlight again! If I have some time, I'll take off the front plastic lens and photograph the assembly.

Suffice it to say that it was a bit of a hassle. I found a lid to a tea tin that would accept the original lens, which allowed me to extend the lens out from the main light body by a centimeter or so. The original plan was to mount the heatsink to the back of this tea tin, which I had hoped would give me enough space for the optics.

But once the optics arrived and I did a test fitting, it was obvious I needed a few more millimeters to clear the front lens. I ended up cutting some small spacers from aluminum bar stock, and epoxying these between the heatsink and the tin lid. This allowed me to put the led optics behind the original lens.

I'm definitely losing a lot of light to diffusion on this old plastic lens, so the light doesn't have nearly as much reach as it could. On the other hand, the diffused light gives a lot of side visibility, and the light that does get through is more than adequate. I would only recommend this approach for a stealth, retro-light where you don't need to squeeze out every last lumen for lighting the road.

Steve

That looks fantastic! Would you mind taking a shot of how you mounted the optics inside? I've been wanting to set up a dynolight for the bar bike, but have not found any way to overcome the bizzare beam patterns...