My homebrew lights .. finally ...

[Amanda P]

So, Fisha, I've got a box full of little bits and it's time to start joining them up. First question: how do I secure the star emitters to the holders? How did you secure the emitter/holder/lens assembly to case?

 

[Amanda P]

He went all quiet. So I did it anyway. Just in case anyone's interested, I used tiny nuts and bolts to secure the star emitters to the aluminium strip, with a smear of heat conduciting gunge between them.

Then I wired them up in series. I used a tiny bit of epoxy on each foot to secure the lens holders in place. (That's the lens holders' feet, not mine). The lenses clip into the holders, but not terribly securely, so I added further tiny blobs of epoxy to secure them further.

When that was all dry, it was straightforward to assemble the whole thing inside the case, which, as Fisha says is exactly the right shape and size. And here's the finished product:

It's about the size of a fag packet - try to ignore the other bikes and lights in the background.

It's a really excellent light, the best I've ever had. I just bought one of the new Busch & Muller IQ Fly lights, and I thought that was good, but this is an order of magnitude better - really bright with a good even beam. The 6 degree lens gives a slightly brighter central area, but it's subtle.

I've not tried the really expensive lights (Dinotte, Ayup and so on) so I can't compare it with those - all I can say is it gives all the light I could need, but cost about £30 all up. I commend it to the house.

Fisha (wherever you are) - thanks a lot.

 

[PrettyboyTim]

Gosh, that's really quite exciting! Or perhaps I'm just a nerd. How much light do you find shines upwards as compared to down to the road? I've always been a bit concerned by some of these ultrabright LED things that they may be too dazzling to other road users and pedestrians.

I currently have the Smart twin halogen lights, but I've been thinking of seeing if I can replace the halogen bulbs with LEDs, as the battery life is pretty pants when I have both lights on.

 

[Amanda P]

You can get LED bulbs that are direct replacements for halogen ones, with constant current gubbins built-in. (not cheap though, unless you build your own like I did). However, I suspect that the LEDs aren't run at full current as there's no real heat dissipation capability. I found that an LED bulb gives about the same light as a 3W halogen. It only draws about 1W, though, so you'd get three times the battery life.

You could have an LED bulb in one light head and a 3 or 6 W halogen in the other. Run the LED in town and use a 6W halogen when you really need the extra light, maybe.

There is quite a bit of light shining upwards, it's true - the light lights overhanging trees and high-up road signs pretty well. But I have the light angled down so that the brightest part of the beam is on the road 10 - 20 yards away. So far no-one's complained of being dazzled by them; then again, I'm having less trouble than I used to with oncoming drivers not dipping their lights on dark roads. So I reckon it's about right.

 

[PrettyboyTim]

Yes, I was looking at those drop-in replacements last night, but as a single one would cost more than the entire light set did, I think building my own is a better idea.

Currently my Smart lights each have a 10W halogen bulb, and I tend to like having them both on, even though my route is streetlit the whole way. I like the way the lights give a good patch of light out in front, so that even pedestrians walking away from me can tell that something's coming. Especially as some of my route is along a cycle path that a lot of pedestrians walk past. I also like to think that a nice pair of bright halogens out in front give me a bit more respect out on the road, but that might just be wishful thinking.

However, 20 Watts of lighting doesn't half race through a battery!

 

[Tharg2007]

hmmm, i like this plan, especially if i could use these new ones --->
http://www.led-tech.de/de/High-Powe...-auf-Triple-Star-Platine-LT-1588_120_138.html

1000+ lumens per star €15

 

[Amanda P]

Those are the same physical size, although if I read the spec right, need more power. So you'd get more light, but need higher voltage to drive all three (I use a pack of 6 NiMH AA cells, giving 7.2V and about 10 Ah). You might need a different driver/constant current as well.

One of these triple stars seems to give three times the light of a single P4, so you could build a light using only one - although that removes the advantage of using two different lenses to give a bright central spot and a wide beam too.

The point is, I suppose, that Fisha's found a combination of case, heatsink, LEDs and optics that looks neat and fits together very neatly. What actual LEDs, driver and batteries you use is up to you.

 

[Downward]

Bookmarked for reading when I get home !

 

[Tharg2007]

average is 3v per emmiter, so 9v , 12v would get allot more out of it. I recon with 9v you would get about 800 lumen out of it, maybe more.
Might look into building one of these with a more compact driver into some kind of tube.

 

[Amanda P]

I've built a number of these Fisha lights. For more recent versions, I've used this constant current circuit, which is slim enough to fit in a tube.

It's supposed to be fixed to something that acts as a heat sink, though. Not sure how you'd do that in a round tube... I'm also not sure how necessary it is - the cases of Fisha lights only barely get warm.

I'd like to be able to switch the light to low power - a full power setting for out in the sticks, and a battery-saving option for use in town where you don't need so much light. I'm sure there'll be a constant-current gadget that can do this, but I lack the knowledge to find it or to be sure of getting the right one.

Any electronics gurus have any advice?

 

[Tharg2007]

One of these triple stars seems to give three times the light of a single P4, so you could build a light using only one - although that removes the advantage of using two different lenses to give a bright central spot and a wide beam too.

The point is, I suppose, that Fisha's found a combination of case, heatsink, LEDs and optics that looks neat and fits together very neatly. What actual LEDs, driver and batteries you use is up to you.

they do single ones too http://www.led-tech.de/en/High-Powe...CREE-XP-G-R4-on-Star-PCB-LT-1567_120_138.html

 

[fossyant]

I have a habit of making light's go up in smoke...literally....... fried my old BLT Lead Acid battery pack...... smoke everywhere....threw pack outside......

 

[Tharg2007]

Uncle Phil,
looking at the specs on the P4 and the Cree XP you seem to get about 100 lumens more for slightly less wattage on the cree. I think these cree emitters are the latest giving more output while conserving power. I can see this things getting better and better over the next few years.

 

[Tharg2007]

I have some more questions,
in fishas pics I would like to know what the connectors are he is using for the external plug, is it water resistant, links would be good.
Is there a switch on the back of the unit? looking at one of fishas pics there seem to be some holes on the rear end cap of the outer housing.
I had a couple more questions but cant think atm.

 

[Amanda P]

He mentions "Tamiya connectors". I think these are used for radio-controlled models, but beyond that I know nothing about them.

I've used these jobbies for lights in the past. For my current "Fisha lights" I've just used insulated automotive spade terminals, and a standard DC coaxial power plug and socket to plug in the charger.

Water resistance isn't as important as you might think, unless you regularly ride your bike underwater in sea water.

My setup has the switch on the battery box, but there's enough room inside the case Fisha suggests to fit a miniature toggle switch on the back panel.

Shortly after starting this thread, Fisha disappeared from the forum - don't expect answers from him. Let's hope it's not because his lights failed!