Cheap Complete Strobe System

[DanH]

mcb,

<<...I was thinking about using K2 stars... >>

I was just over at the Phillips Lumiled site and don't recall a listing for K2 stars, just emitters. Do they make them?

<<My landing lights are HID and thus I can't wig-wag them,..>>

Hmm, I was also leafing through the lighting section in the Spruce catalog this AM and came across the "Aviflash HID and Halogen Lamp Flasher". Went back and looked it up for you, PN 11-04412, $59.85

[mburch]

Originally Posted by DanH

I was just over at the Phillips Lumiled site and don't recall a listing for K2 stars, just emitters. Do they make them?

I think they are a third-party item, not made by Phillips, but you can get a K2 star in the same footprint here: http://www.luxeonstar.com/ The backplate is also electrically isolated, which is a nice bonus.

Originally Posted by DanH

I was also leafing through the lighting section in the Spruce catalog this AM and came across the "Aviflash HID and Halogen Lamp Flasher".

Yeah, I actually bought one of those as an impulse purchase a while back. However, I think I'm too chicken to actually hook it to my landing lights. I talked to Bill VonDane about it and he says he's had no problems on his airplane, but I want to be extra conservative about shortening the life of my expensive light bulbs!

mcb

[Pirkka]

Originally Posted by mburch

I may end up buying a few to play with once I get around to working on the wingtips.

Go for it and let us know how you successed.

You said that you wanted visibility - to whom? If you want that others will see you I strongly suggest using very short pulses and overdriving LEDs. While you are doing your testing, just try it. Very short pulses doesn't heat up LEDs much but are more visible.

You actually don't need LEDs to do testing: get two similar lamps, one around 40W and one 100W. Put them side by side and try different timings -- do you ever get the feeling that 40W lamp would beat 100W even how long it would be on? And even 100W would be on just a fraction of a second. Comparison may not be fair because I'm not sure how fast bulbs turn on. LEDs turn on very quickly so therefore their pulses can be very short.

I don't see how Stars would be so superior... I would consider just emitters -- gives more flexibility how to arrange them and then they can be casted in epoxy if wanted.

[the_other_dougreeves]

Originally Posted by Pirkka

I don't see how Stars would be so superior... I would consider just emitters -- gives more flexibility how to arrange them and then they can be casted in epoxy if wanted.

Stars are, IMHO, easier to mount than emitters. Emitters look better when mounted properly. Stars are easily mounted to existing aluminum surfaces using the thermal adhesive.

[MTBehnke]

Originally Posted by DanH

Good work, very useful! What does the formula say for white?

The datasheets give the same graphs for the green and the white light distribution, and the white gives out about 85% of the lumens as the green. Since the green seems to range from 13.6 to 18 candles, the white should range from 11.5 to 15.2 candles.

Note, the datasheets give a range of light distribution pattern values for the green (and white). With the same light output, but in a more narrow band, the intensity could be as high as 18 lumens. Using the somewhat broader band, the peak intensity could be closer to 13.6 candles.

[DanH]

<<the white should range from 11.5 to 15.2 candles>>

Thanks Mike.

I've been reading datasheets, etc. Dumb student has more questions for anyone willing.

Am I correct in thinking that all Luxeon emitters (I, III, V, etc) have the same forward voltage drops, ie 2.95 for red and 3.42 for green and white? This is a standard, a function of their physics?

On another front, just how weather resistant are these things? I'm not talking about salt spray, just ordinary moisture and UV effects. Could you thermal epoxy a Star to an external aluminum surface and expect it to live, or does it really need lens coverage?

[Paul Eastham]

Originally Posted by DanH

Am I correct in thinking that all Luxeon emitters (I, III, V, etc) have the same forward voltage drops, ie 2.95 for red and 3.42 for green and white? This is a standard, a function of their physics?

I believe they differ at least slightly, but they are in that ballpark. It is on the data sheet for each model, search for "voltage drop" or "forward voltage".

As for durability, they seem tough after some rough handling by yours truly (dropping them on the floor, etc), and the stars do seem to have some built-in anti-static diodes, but I haven't seen any specific specs on what you can expect except for temperature ranges.

[DanH]

<<It is on the data sheet for each model, search for "voltage drop" or "forward voltage".>>

Got it, thanks Paul. Now I see it varies with drive current too.

Ok, I boldly propose to use three Luxeon III's per tip driven at 1000mA with a single 2008B PowerPuck. 1000mA is the max current for green (80 luminous flux). Reds can be driven at 1400mA for 140 luminous flux; the charts says about 105 underdriven at 1000mA. That should put them in the same ballpark in perceived brightness.

Three Lux III's per side seems to conserve real estate, but I've not waded through the heat sink equations yet (ugg!). Three of these may need the same heat sink as the six 1W that Sparky used, so perhaps I wouldn't really save any space. I would save a few bucks on the power supplies as I would only need two.

What say ye wise men? Always happy to have the education.

[the_other_dougreeves]

Originally Posted by DanH

Ok, I boldly propose to use three Luxeon III's per tip driven at 1000mA with a single 2008B PowerPuck. 1000mA is the max current for green (80 luminous flux). Reds can be driven at 1400mA for 140 luminous flux; the charts says about 105 underdriven at 1000mA. That should put them in the same ballpark in perceived brightness.

That should work - 3 x LuxIII should be PLENTY. That will allow you to get sufficient coverage. I'd drive them at 1000 or even 700mA - given that you are using 3 emitters, 700mA (60 lumens) should be fine. That will result in lower heatsink requirements. The PowerPucks are good, reliable drivers, BTW.

[DanH]

Thinking about the tail light. Mike, does your spreadsheet indicate that a single white Luxeon III might satisfy the tail requirement? I'm guessing a LuxIII is bright enough at peak, but maybe not bright enough at the 140 degree edge.

Second item. I've not worked with the thermal epoxy (Arctic Alumina?) used to mount stars on a heat sink. Here's the question (hello Sparky!); do you think you could cast this epoxy?