Author Topic: My questions  (Read 9163 times)
Ash
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Re: My questions « Reply #45 on: October 26, 2015, 05:41:38 PM » Author: Ash
What i am asking is - Assume the road is evenly lit at exactly the minimum level

If we drop the brightness more down in all the road it will be "too dark"

If we drop the brightness more down in the parts between the poles it will be "too dark"

But what if we drop the brightness more down in the parts between the poles, but light a bit more under the poles, so that the overall power use is as initially ? This is indeed less than optimal, but for relatively small ratios between the 0L and 2L points, can't we "get over it" ?
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Medved
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Re: My questions « Reply #46 on: October 27, 2015, 01:35:51 AM » Author: Medved
What i am asking is - Assume the road is evenly lit at exactly the minimum level

If we drop the brightness more down in all the road it will be "too dark"

If we drop the brightness more down in the parts between the poles it will be "too dark"

But what if we drop the brightness more down in the parts between the poles, but light a bit more under the poles, so that the overall power use is as initially ? This is indeed less than optimal, but for relatively small ratios between the 0L and 2L points, can't we "get over it" ?

Giving enough time to adopt, the overall brightness reduction will maintain better visibility. On many places I would even say less light would be better: Even with the imperfections (shadows from other objects,...), the car headlights would provide sufficient supplementary illumination, so you will see there without the glare from the brightly lit surroundings.
If you drop just the brightness between the poles, the brighter sections will just glare you and so the visibility on the darker section is reduced even when the level there is still higher than the case above.

By the way I have very bad personal experience with one type of very problematic lantern design: The light thrown just underneath the lantern came from just very small section of the lens. So small, the pole had made really dark shadow. The lantern was directed onto a small parking lot, so the shadow went in the road direction. And as the Murphy's laws go, there was deep pothole in the road was just in the place of the pole shadow, so I completely overlooked it. And it happened to be just in the way of my right wheel when going the "ideal path" (of course within my lane, it was slight curve), so I just hit the hole. At that time nothing appeared to be damaged, so I continued further. Then after few weeks (well, there was some negligence on my side to do thorough check after the hit) I just run on a road with some small bumps and the right front tire went flat at instant - at 90km/hour and in a road bend. I'm glad I managed to remain focused on what had happened and didn't do any stupidity like slamming the brakes or so... Well, I have found, hitting the hidden pothole had bend the rim, so the tire just held the air on just tiny corner of rubber. The uneven road then caused this corner to detach, so loosing all the air at once...
So even when small, the dark areas in lit background are extremely dangerous, even when the place appears to be lit well.
And by the way the lantern there was some HPS, it was at the time, when no one even considered LED's for road lighting. It was just wrongly installed (an overlooked pothole on the parking lot, where you move just the walking speed, will have less consequences than on the road, where you drive 50km/h)... And I would expect when that light would be of lower power, the pothole may appear at least when illuminated by the headlights. But because the level there was really high, the headlights had no power to overcome the glare from the brightness around that pole shadow.

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xelareverse
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Re: My questions « Reply #47 on: November 15, 2015, 02:22:21 AM » Author: xelareverse
Will a 12v ballast for cars run a phillips 35 watt par 30 cmh lamp? ???
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Medved
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Re: My questions « Reply #48 on: November 15, 2015, 03:31:34 AM » Author: Medved
Will a 12v ballast for cars run a phillips 35 watt par 30 cmh lamp? ???

It may work, but there are some risks:

It will overdrive the lamp after power ON (the power boosting functionality designed to compensate the lower efficacy of the Xenon buffer to meet the output required by the road standards). Problem is, standard CMH is not designed for that, so it may affect the life.

The voltage profile mainly during warmup may exceed the limits programmed into the ballast and so the ballast may shut down (thinking the lamp is faulty)

It uses >20kV pulse ignitor (to be able to hot start the Xenon buffered lamp), so at aa hot restrike attempt may cause insulation problems mainly on the socket (and maybe some X-ray generation, but that dose would be extremely low due to the shut down protection in the ballast and very short pulse time).
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dor123
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Re: My questions « Reply #49 on: November 15, 2015, 06:03:05 AM » Author: dor123
I've seen two videos of L_V and xtreminatorxtrem , which operated Philips CDM-T 35W on 12V MH automotive ballasts, and their ballasts didn't shutted down (xtreminatorxtrem used a Mitsubishi Electric ballast), and xtreminatorxtrem managed to hot restrike the CDM-T without problems (Probably because the compact CDM lamps can be hot restriked with a 30KV ignitor or electronic ballast anyway...).
Philips electronic ballasts for MH lamps, have a power boosting anyway, as lamps on their electronic ballasts, runs-up faster than on magnetic ballasts.
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I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.

I only working with the international date format (dd.mm.yyyy).

I lives in Israel, which is a 220-240V, 50hz country.

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