Comments on: Schmidt hub + dual Cree XR-E LED light

By: Walter Page

Walter Page — Fri, 07 Mar 2008 17:34:37 +0000

I have the will to build but zero knowledge of electronics. Would it be possible to give a url to the exact parts to buy to build “a Schottky full wave bridge rectifier”? Maybe you could also do the same for the “high powered TIP3055 shunt transistor with 27V zener diode”. I guess I should put one of those in also. I already have the LED’s and a controller. I bought all this stuff last winter in anticipation of PBP, but unlike you, the project never came to fruition. I also bought a TuneCharger. My late Spring experiment, last year, driving an LED light with a Schmitt hub through the TuneCharger emphatically showed that the TuneCharger does not put out the kind of current that Fatman boards like!!!

I particularly liked your “test stand”. I have an old frame mounted on a trainer which is powered by a 1/4 hp electric motor driving through a number of v-belts and chains to the left side of the bottom bracket. On the right side the normal drive train operates. There is a fork mounted on a hinge which is attached to the seat post and carries the wheel with the generator hub. When it all gets going it is quite scary! I can definitely see that your system, at 30 mph, could be life threatening.

Thanks, Walter

By: brotherdan

brotherdan — Thu, 17 Jan 2008 07:17:38 +0000

Thanks for the post. Your results are impressive and inspiring. I just purchased a dynohub and I’m not too happy with my current lighting setup. I think I’m going to try to emulate what you have done here, but I want to run a set of LED taillights off the hub as well.

By: Ride Report: 11.15.07 « Pedalling Along

Ride Report: 11.15.07 « Pedalling Along — Fri, 16 Nov 2007 15:24:24 +0000

[...] There also appear to be home built LED lights that put out alot more and cost a bit less, but I don’t think I have it in me to successfully build one. Here is one that I found that folks seem pretty excited about: http://joegross.net/2007/08/14/schmidt-hub-dual-cree-xr-e-led-light/ [...]

By: MitchK

MitchK — Thu, 25 Oct 2007 05:12:05 +0000

A few follow-up questions…

Where did you get the momentary switches, rubber caps, and strain relief plug?

With the nFlex/momentary switch setup, do you need to turn the light back on once the wheel stops? (Yes, you’ve got me pondering the possibility of re-entering the dynahub world.)

Have you used them in strobe mode at all? I’m curious if you can get a very high frequency strobe (>=120 flashes/minute) with the nFlex.

Thanks,
Mitch

By: jgross

jgross — Wed, 24 Oct 2007 04:44:27 +0000

That’s awesome! I’ve love to see photos.

I recommend leaving both lights at 1A. The hub is trying to produce constant current and the LEDs are more efficient at low current.

Since any ‘extra’ current is going to go through your shunt and get wasted I think you’re best off leaving both lights on the highest setting all the time.

By: Brenden

Brenden — Tue, 23 Oct 2007 16:12:52 +0000

I wanted to let you know that I used your design to make two lights of my own. I’m still finishing up the second light but I put the first one on last night and I just can’t believe how bright it is. With the strobe setting it’s also extremely useful as a commuting light. I just want to thank you for publishing this detailed account of your light construction. These lights are so much brighter than the Busch and Mueller Lumotec Fly that I bought. I’m really impressed. I haven’t messed around with the Current Drive setting yet, it’s still at 350ma. Maybe they will be even brighter if I turn up the juice? We’ll see. Thanks!

By: MitchK

MitchK — Thu, 18 Oct 2007 19:08:32 +0000

Thanks a lot, I appreciate it. I’ll definitely send a photo link when it’s done. Project completion (hasn’t even started yet) is 4+ weeks out, but I won’t forget.

By: jgross

jgross — Thu, 18 Oct 2007 18:56:47 +0000

(measured without calipers). Outside diameter is exactly 1″. Inside is about 27/32″

Please take a photo and post a link to your completed light. I’d like to see how it turns out.

By: MitchK

MitchK — Thu, 18 Oct 2007 18:50:02 +0000

Thanks, that makes it even simpler. I have some thermally-resistant auto/marine silicone sealant I bought at Ace. I’ve been using it on my recent lighting projects, and it should do the trick.

Do you recall the inside width(s) of the tubing you used?

I forgot to say above: Thanks for taking the time to publish the writeup and photos! I share your sense of simplicity and redundancy (and fork-level mounting), so I think this design will work very well for me.

By: jgross

jgross — Thu, 18 Oct 2007 18:44:53 +0000

The lens has an almost perfect fit inside the tube. I applied some silicone sealant to the sides of the lens before inserting into the tube and then ran a thin seal carefully along the outside edge just to be safe.

I also put some silicone under the switch caps as well as around the strain relief on the bottom. It’s *probably* airtight, but I didn’t test that.

I used “GE Silicone II window and door” which I picked up at the local Home Depot.