# Sternum Lights?



## codypop (Nov 27, 2008)

First post, so please excuse any etiquette breaches.

I am interested in using a sternum light in conjunction with a headlamp for night trail running. I am currently using a PT Apex, old school emitter which will be modded soon (thanks for the inspiration) but find that the shadowless beam gives no indication of surface irregularities, leading to a lot of faceplants.

I haven't read any reviews of the GoMotion Sternum 3 watt Luxeon Led Kit on CPF so was wondering what others thought of the light quality and battery capacity (3 * AA).

An option I was tossing up was to make my own sternum light out of the optics from a LED Lenser H7 but replace the battery pack with a 4 * AA and a decent regulator / dimmer circuit. From what I've read here the gripe isn't with the LED Lenser's optics but regulator (or lack of) and battery capacity.

Thanks a lot for your helpful forum!

codypop


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## Blue72 (Nov 29, 2008)

That looks really cool.

I mounted a ARC AAA on the shoulder strap of my Camelbak for when I do outdoor activities. It works really well. The only problem I have and would be the same problem with the sternum light is that when you turn your head there is no light and you have to move your whole body to see whats there. However, on the plus side it is a great way to have a hands free light without having something strapped to your head. It also reduces any glare you get in your eyes as well.

here is a pic of my setup


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## Flying Turtle (Nov 29, 2008)

Sometime just walking around the house I use my Zebralight as a sternum light, clipped to my shirt. Perhaps, used on a medium or high level, it would give enough light immediately in front of you to do the job. 

Geoff


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## monkeyboy (Nov 29, 2008)

Hello Codypop
Welcome to CPF

I didn't even know "sternum" lights existed. I guess they would be more comfortable than headlamps and would show up dips and potholes better. It's really easy to twist your ankle running at night with just a headlamp (I've tried). I usually accompany a headlamp with a handheld flashlight.

The Luxeon 3 emitter in the Gomotion light that you linked is now considered to be old technology. The latest Seoul and Cree emitters now have about three times the efficiency of the old Lux 3. I think The best idea would be to mod a headlamp into a sternum lamp, for example, the Petzyl Myo XP (seoul version).


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## codypop (Nov 30, 2008)

Thanks for the replies. The local forestry trail where I do night runs is very rooty and rocky, and the lamp above my eyes means I get no shadow to see where a trip hazard might be.

I'll fit my old Tikka XP with a wide elastic strap and try it as suggested, If I can see the difference I'll post some photos. With the diffuser 1/2 way across it gives about the right combination of flood and throw for trail running, but you always want more, right?

codypop


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## hopkins (Nov 30, 2008)

cody -many of us have noted the shadow problem with just a headlamp.

Those Orienteers in Finland use huge headlamps to solve the problem.
Somewhere in the CPF one of them said the old APEX was nice but only a toy for kids, and not for serious adults jogging through the taiga. suspect they know a thing or two.

Here's a link so you can feel underpowered as I do with my Petzl Myo Xp.
MILA headlamps...
http://thegearjunkie.com/gear-junkie-scoop-mila-pls-100-headlamp


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## codypop (Nov 30, 2008)

I see your 300, and I raise you 1100

Betty X Pro

That's one way to avoid tripping - turn the trail into slag!


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## Jagge (Nov 30, 2008)

Right, Lupines are quite common here. I don't think those are overkill, but this one is:

http://vaajakoskentera.com/kurkocup08/

See image posted 7.11.2008, halfway down the page. Winner of that race used that 3000 lumen DIY headlamp.

I am not sure, but you may see it in action on this video, it's shot 2 weeks ago:
http://www.youtube.com/watch?v=FlzLTR5z-fY

My opinion is 700-800 lumen is about enough, having 3000 lumen is just too much extra weight for nothing.


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## Woods Walker (Nov 30, 2008)

dd61999 said:


> That looks really cool.
> 
> I mounted a ARC AAA on the shoulder strap of my Camelbak for when I do outdoor activities. It works really well. The only problem I have and would be the same problem with the sternum light is that when you turn your head there is no light and you have to move your whole body to see whats there. However, on the plus side it is a great way to have a hands free light without having something strapped to your head. It also reduces any glare you get in your eyes as well.
> 
> here is a pic of my setup


 

Nice...


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## vtunderground (Nov 30, 2008)

I've taken my PT EOS off of the head strap, and put it on the sternum strap of my backpack. Worked just fine.


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## Jagge (Dec 1, 2008)

hopkins said:


> cody -many of us have noted the shadow problem with just a headlamp.
> 
> Those Orienteers in Finland use huge headlamps to solve the problem.



About the shadowless beam and 2D vision problem as aresult of it:

(1) you need enough output. (2) you need to move the emitter further away from your eyes (up). 

Most cheap low output lighits like this LL has light source low on your forehead, close to your eyes. As a result you get almost no. And if you have lots of output there, you will not see much at all in rain or fog (just think about really bright and tight beam hitting fog only about 4 centimeters from your eyes) and you get easily blinded if something gets close to your eyes (your hand, a map, branch etc.)

If you put it on your sholder, you'll get shadows and see surface irregularities, but you will not see any objects close to your eyes - branches etc- so you easily hit your face and may get your eyes injured. 2 light setup works slightly better, lightwight low output headlamp for spotting branches and reading map, belt or shoulder light with more output for illuminatin trail. But you will always have to turn your whole body to turn your light to some direction. 

Better option is simply liftin light source slighty up like it is done is most high output headlamps. You'll see branches that are about to hit your face, you get a little more shadow, you can have lots of output without getting blindede that easily and you can point your light anywhere you want just by moving your head.

Just my 2 euro cents as an natural born orienteer from Finland...


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## degarb (Dec 2, 2008)

I tried a 120 ish lumen sternum light last year for tasking--painting, weedwacking (pointed down), garage cleaning. I didn't like it at all, since only about 25% of time the light was pointed where I needed it. And, two lights means more batteries to charge so every lumen counts.

I found a pointable (left, non dominate) wristlight with throw to be the perfect solution--quick to whip around, illuminates feet, backup for headlamp, can shine up laps, straff walls to see textural profile, exponentially brighter for walls below waiste.

Now this light could be adapted for the wrist, if it had some pivotable or gooseneck to point where I need it.

Then again, I think this light will sell well, because: A. there are people who refuse to look like a geek and wear a headlamp. B. A product doesn't have to work to sell well, only look like it works well. And what is cooler than a shoulder light. The guys in Jurassic park wore them.


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## Guy's Dropper (Dec 4, 2008)

"Chestlights" were more common a couple dozen years ago.


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## Blue72 (Dec 4, 2008)

Guy's Dropper said:


> "Chestlights" were more common a couple dozen years ago.



THAT IS COOL!!!!


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## Mdinana (Dec 4, 2008)

Did those come out about the time the original Iron Man did?


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## PeLu (Dec 4, 2008)

Guy's Dropper said:


> "Chestlights" were more common a couple dozen years ago.


 And even the centuries before. Google for 'Freiburger Blende'. I've seen such lamps used as sternum ligth.


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## smfranke (Dec 7, 2008)

lol - the first thing (person?) I thought of when I saw the thread title was Iron Man & then I saw your avatar 

I never thought of any other location than the head, hand or wrist. Another option is always good to have...


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## codypop (Mar 29, 2009)

Well the wife and I finally got to go trail running last night. She used the GoMotion Sternum Light as she had found after a few hours she got a headache from our Tikka XP.

Her first impression was that the position of the light, below her eyes, gave her a much better idea of the surface topography than a headlamp does. She suffers from weak ankles for a trail runner and she often turns one while out at night. There were a few opportunities to do that but she managed to avoid them completely for a change.

The position of the light did present other challenges, however. She found when pumping her arms the flashing of the light on her hands and the blinking shadow in front was like a disco. She went blind every time she reached for the drinking tube on her pack. When she went sideways to skirt a puddle there was suddenly no light on the path. And when she wanted to see something, she had to point her sternum at it, not easy at all.

We concluded it would be best coupled with a small headlamp. She'll probably keep using the Tikka XP for this purpose.

Plenty of light output from the GoMotion since I put in a new emitter, replacing the stock Luxeon with a Seoul star from Photon Fanatic. There is nothing remarkable about the inside of the light except for the amount of electronics inside it - there is a multi level switching regulator board in the light "head" and a charger (of all things) taking up a ton of space in the remote battery pack. The cable between the two units is six core - darned if I can figure out what they're all for. There is a fair amount of nice custom molding in the light head but water resistance is obtained by a thin bead of neutral cure silicon rubber run around the join between the two halves of the case.

Most interesting feature inside? The star is mounted to a "plastic" heatsink - probably an aluminium loaded epoxy - that is moulded in one piece as the back of the case and ribbed heatsink.

Here is her blog on the run.


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## whosywhat (Jan 18, 2010)

I received one of these GoMotion kits (3-Watt Waist Kit) as a gift. It didn't put out enough light, so I looked around and found this post about upgrading to a SSC P4. Now that I've done the mod, it's nice and bright, but the light shuts off if you bump or rattle it even slightly. 

It doesn't seem to matter how bright I have it set, if I tap the light, it turns off. (And then the green led on the pwr button blinks 4 times.) If I just let the light sit there, it will stay on just fine (although the little battery indicator led stays RED the whole time). 

*Codypop,* If you still have your GoMotion with the SSC P4, does a red LED light come on (near the pwr button) when it is on at the highest setting? Also, with the light off, can you get the little green LED to blink by tapping on the battery box?


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## codypop (Jan 27, 2010)

whosywhat said:


> I received one of these GoMotion kits (3-Watt Waist Kit) as a gift. It didn't put out enough light, so I looked around and found this post about upgrading to a SSC P4. Now that I've done the mod, it's nice and bright, but the light shuts off if you bump or rattle it even slightly.
> 
> It doesn't seem to matter how bright I have it set, if I tap the light, it turns off. (And then the green led on the pwr button blinks 4 times.) If I just let the light sit there, it will stay on just fine (although the little battery indicator led stays RED the whole time).
> 
> *Codypop,* If you still have your GoMotion with the SSC P4, does a red LED light come on (near the pwr button) when it is on at the highest setting? Also, with the light off, can you get the little green LED to blink by tapping on the battery box?


Whosywhat, from looking at the reaction of my GoMotion to a battery being even momentarily rattled in the battery case (sudden total darkness, four blinks from the green power light) I'd say you've got a fault in the wiring or componentry of the front case there.

GoMotion possibly won't help you out now you've cracked the case, but it might be worth ringing them up anonymously to find out.

If they won't accept it for repair, I would suggest that as a first port of call you pull the thing open again and make sure none of the multitude of wires crammed into the front case are jammed or pulled off the circuit board. Check with a magnifying glass and a strong light that there are no solder dags or other shorts on the board. Do all of the usual blind fault finding things - tug on the wires (one at a time, and fix them if they come off before tugging the next). Carefully put the batteries back in and flex the board gently to see whether there is a cracked track. With the case open, you can wiggle one wire / component at a time of the front assembly, and maybe isolate the fault to a particular connection, wire, or component. Check that none of the components on the PCB have been "compromised" by being crushed when the case halves were reassembled.

The red light is a low battery indicator. It is green when the batteries have sufficient juice to supply the load. Are the batteries up to the task? This may be another symptom of the wiring trouble, or it may be a red herring.

If all of this doesn't work wash the circuit board with a flux cleaner carefully. Methylated spirits and an old toothbrush are good for this. This procedure is good for removing small shorts you can't see.

Did you use neutral cure silicone rubber - the one without the vinegar smell? The acetic acid released by the non-neutral cure (vinegar smelling) stuff will corrode circuit boards and components.

Sorry if the tone is a bit "Electronics 101", I don't know your experience or skill level. I'm trying to be helpful, not condescending.

Best of luck with it, let us know how it goes. Sorry for the slow reply.


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## codypop (Jan 27, 2010)

whosywhat said:


> Also, with the light off, can you get the little green LED to blink by tapping on the battery box?


Sorry, didn't see/register this.
The light blinks in this manner if there is a momentary disconnection of the power. It could be that bumping the battery case is moving the front assembly, which already seems to have a problem. Or it could be that you have a problem at the rear case as well. Check the battery springs are tight. The battery compartment is a bugger to use with AA cells as the centre one is a bit tight. Do you have those or the optional rechargeable? Check the rechargeable is plugged securely into its connector if that is your configuration. But it sounds like the front case causing a rear case symptom.


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