HID Fluctuation?

[FRITZHID]

while doing a runtime test on the Hand-Sun, i noticed in my peripheral vision, a slight fluctuation in the light from the HID,... is this normal? it's not extreme, or constant, just happens every now and then for a second or two. is there a way to eliminate this? the power and connections are rock solid, the lights indoors and not moving, no wind or thermal changes. just seems odd to me... perhaps its a natural occurrence of a new bulb? any ideas guys?

[FRITZHID]

^^^^ That was at 1hr run time, now at 1.5 hrs, i can see movement in the hot spot, it's not alot, just a lil flicker, but none the less, is this normal???

[ma_sha1]

I'd say not normal, I haven't see this.
Perhaps, ballast is not stable? Does it happen with a different lamp?

[BVH]

I did a lot of reading of the very detailed technical white paper of the Cermax type of bulbs used in the Megaray. They are DC short arcs. They describe "flickering" as an occasional apparent change in light output. I just received a new bulb and was breaking it in and noticed some flickering. The burn and light output was nice and steady but every once in a while, the hotspot would change shape a tiny bit and I noticed a change in light output. Not really more or less light, but a change. It's caused by very small, sometimes microscopic, movements of the arc on the cathode tip. It can sometimes take the form of a periodic light modulation or it can take the form of a sudden rise or drop of a few percentage points in the light output, occurring anywhere from once every few minutes to once an hour. I'm not sure flickering as I describe it here is found with AC bulbs. Does this describe what you're seeing? Or is it more of a very high frequency flicker - something that is best seen via your peripheral vision? I've seen it with some systems/bulbs.

[FRITZHID]

idk, i'm in the middle of a runtime test or i'd check. i'll pop another bulb in later and see. it diden't happen with the SLA, but i'm not seeing any A or V changes out of the ordinary.
the bulb in this light is a 55w, maybe a 35w won't due to the shorter arc length.
i took a peak at the arc using polarizing films so i diden't go blind, and noticed the arc itself is arched upward and moving slightly. perhaps a heat issue? maybe just natural due to long arc length?
i have some replacement bulbs coming for free since 1 of the bulbs i received was to long, maybe i'll try taking the whole thing apart and seeing if i can retrofit a higher quality bulb in the bulb base since i don't know where else to get Bi-Xenon bulbs.

[alpg88]

not normal, i had that happen, one of the ballasts in the kit did that, other didn't. at first i swapped the bulb it didn't help, changing the ballast helped.
however, both bulbs\ ballasts do that flicker few times until they heat up, after 30 sec, or so it goes away, the defective ballast did that all the time,

[FRITZHID]

well, the runtime test just ended (2 hrs, not bad but i'd hoped for a lil more) and in answer to BVH, yes kind of a flicker, but it got worse as time went on, and then the hotspot was noticeably moving back and forth, not with any kind of rhythm, but just bouncing a little. maybe 1/4" at 10'. its not a high freq flicker, more of a random pulse or twitch. light OP diden't change, the overall beam wasen't horridly effected. just noticed it at 1st in my peripheral vision, then as it progressed, i could see the hotspot itself flickering. thats when i took the polerizing film to it so i could get a closer look.
if i can get it on vid at some point, i'll post it here.
it doesent seem to happen while the ballast is cool, and i don't recall it happening with the SLA, so maybe the higher voltage is the culprit?

[BVH]

Sure sounds like the definition of flicker of the Cermax type bulb. I forget your battery and ballast specs but is it a 4S lipo and what is the printed input voltage range on the ballast? Try the SLA temporarily again to see if it's still there. If not, then maybe the ballast can't hack the additional Voltage.

[get-lit]

Typical arc instability. Could be the ballast, but be sure to run the lamp for a good 1/2 hour minimum every couple startups for the cathode to reform/reshape properly after the ignition spark deforms it. If the lamp has been ignited frequently for just short periods of time, you'll need to run if for a few hours to attempt to reform the cathode. Frequent ignitions without time to reform the cathode will most definitely cause arc instability. Other than that, it's likely just a less mannered ballast.

[FRITZHID]

ok, new ballast AND new bulb... AND using SLA.... same thing. :/ cheap ballast and bulb combo maybe? it's not overwhelming, just annoying.... IMO. i'm sure most people using/walking with this light would never notice, not to mention MOST people woulden't sit there with a light on the wall for hrs on end while starring at it. lol

[get-lit]

It takes a "smart" ballast to control the arc well. These are not just any ballast, and they're not cheap. Smart ballasts don't just power the lamp, they sense the condition of the lamp and control it accordingly. They're made by optoelectronic gurus, notably from Germany that are obsessed with this stuff.

[FRITZHID]

It takes a "smart" ballast to control the arc well. These are not just any ballast, and they're not cheap. Smart ballasts don't just power the lamp, they sense the condition of the lamp and control it accordingly. They're made by optoelectronic gurus, notably from Germany that are obsessed with this stuff.

Figures.
so, my choices are, deal with it, or pay a fortune for specialty ballasts. ....wonder which one i'll choose.

[BVH]

I'd say the vast majority of the typical automotive ballasts and bulbs do not exhibit this problem. You just ended up with some that do.

[FRITZHID]

figures... and the sad part is i ordered from a comp on ebay that got high reviews here on CPF. :/

[get-lit]

Projecting the light with a large reflector is like magnifying the light source. Subtle movement of the plasma ball is exaggerated as opposed to an automotive reflector. The smart ballasts I was referring to are for short arc lamps. Try a different ballast to see if it's any better, Philips, Osram, or any ballast the comes stock with a good automobile.

[bshanahan14rulz]

Are the bulbs oriented vertically or horizontally? These were meant to be operated close to horizontal, +/- 15* or so.

[get-lit]

Excellent point. That will cause instability. I'm sure they're mounted axially; so when the light is pointing upward, they could become unstable.

EDIT: FRITZHID said he's really scrutinizing to notice, so it's probably not a big deal for this application. I'm sure you'll still get an easy 1000 hours.

[FRITZHID]

they are being run Horz just like they would be in a headlamp. and with the Parabolic magnification, everything in multiplied so every lil fluctuation is seen, and yes, i am a tad picky so i am seeing stuff the most people wouldn't notice or be bothered by, lol.

[get-lit]

To be sure I understand, you see this when the light is mounted horizontally and your light is pointed horizontally? If that's the case, then the magnification aspect is the issue. I'm using the most advanced smart ballast and a universallly mountable lamp, and in full spot mode I still see an ever so slight, hardly noticeable "aurora" in the clouds around the beam center. I actually like it. It's like an alien tractor beam.

[alpg88]

i am a tad picky so i am seeing stuff the most people wouldn't notice or be bothered by, lol.

those people aren't flashoholics.

[FRITZHID]

To be sure I understand, you see this when the light is mounted horizontally and your light is pointed horizontally? If that's the case, then the magnification aspect is the issue. I'm using the most advanced smart ballast and a universallly mountable lamp, and in full spot mode I still see an ever so slight, hardly noticeable "aurora" in the clouds around the beam center. I actually like it. It's like an alien tractor beam.

yes, both are horz, just like they would be in an auto application. when i look at the arc (using polerizing film ofcorse) i can see the arc curving upward (as if heat were drawing it) and i can see slight movement in the arc on the outer electrode. the inner electrode seems alot more stable.

those people aren't flashoholics.

this is tru, but some flashaholics may buy my lights and i'd prefer to have answers rather then "hmmm IDK, I'll have to look into that for you". and i hate BS'n anyone so without that being normal i couldent tell someone "thats totally normal, get used to it".... is just wrong to me, unless it IS normal.




thanks for the info guys, i appreciate it very much.

[bshanahan14rulz]

Old thread, but I did just think of something. I know this seems like a step backwards, but what if you tried a generic 35W ballast? And then what if you tried an OEM automotive 35W ballast? I think it may have to do with the feedback circuitry in the ballast.

Here's a link, and the post I'm referring to is by member D1S, who (If I remember correctly) is a reputable member here under a different name.
http://www.hidplanet.com/forums/show...l=1#post266022