# Starting my HMI project



## stuartsjg (Feb 8, 2014)

Hi, first post so hi everyone. 

I've always been a fan of bright lights. Used to make carbon arc lamps as a teenager, also made a few filament lamps in big glass flasks using fridge compressors as a vacuum pump etc.

Anyway, more on that another day.

I'm looking to build an HMI spot light. Have bought a 1200w HMI double ended from eBay. I also bought a 1200w "faulty" ballast unit from eBay. (Google " Strand Lighting QuartzColor 1200w Compact Daylight HMI / MSR Ballast (magnetic ballast. Model: 2077." and it should come up)

Also got a Vagnini & Wilson IGK 06 1800w Ignitor, eBay too.

Also for a bargain price I've got in the post a CSR 1200 single ended, guess from where.

Got the ballast working, turned out one the 5 PFC caps was knackered and tripped the ballast out. Fuses on the PCB were blown too.

Removed the offending capacitor, replaced fuses and fitted a 13a plug and ballast works perfectly! 

Hooked up lamp and ignitor and it fired up first time with no drama.

Ran about 15 mins before I shut down as the pvc cables going to the lamp were getting cooked with the heat off it.

I do have pix and a video, I'll upload when next on the PC. 

Anyway. My main question is about reflectors. At this time I won't make one, looks alot of mess and my wife won't like that.

Firstly, the diameter. there are several large (400mm+ diameter) reflectors on this forum for this size of lamps. Looking at commercial housing , they have 150-250mm diameter reflectors. 

What difference (other than the obvious beam diameter) does the diameter of the reflector make to the beam?

Is there a general rule or guide that larger reflector have some advantages over smaller ones?

Finally, on lamp mounting. With commercial searchlight, Skyscanners etc, the lamp is axially located through the centre of the reflector via a hole.

However, the Arri fresnel style movie set lamp housing and many home brew reflector have the lamp mounted parallel to /lain across the opening if you like, of the reflector. 

My gut feeling is an axial mount through the centre is easier to adjust and focus etc by just moving the reflector.

Again, I may have missed something there.

Thanks,
Stuart


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## get-lit (Feb 8, 2014)

Welcome to the forum. These questions are much more involved than you realize. Your best bet is to begin by reading the related threads on the forum.


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## stuartsjg (Feb 9, 2014)

Hi, Thanks for the welome. Have been reading the threads for the last few months and much of the lamp mounting appears to be personal preference and how it fits with your construction.

Also read my bible of HMI lamps, the Osram photo optic guide for HMI lamps http://assets.sylvania.com/assets/documents/ENGR_BLTN7.13e279c9-3eba-4850-b60d-7347f23ab996.pdf and Osram themselves use both mounting methods.

The sealed beam par lamps use a parallel mount (and create a beam which carries the aspect of the arc dimensions) where as their projector bulbs are axial.

Pretty sure ill go axial. It just seams right unless there are compelling arguments.

On the reflector, i am used to dealing with microwave links so i think of size as gain. So far as i can tell, the same applies. Larger reflector even with the same lamp and same amount of light gathered by the reflector, the further the beam will go.

However, from reading up about it, even with small reflectors, accurate alignment with the centre can make up for reflector size. The VSS-3, albeit xenon, is a great example of distance from small diameters. 

Ive two reflector options, the 18" reflector from Edmund Optics or one from Aliexpress for use with Xenon searchlights, http://www.aliexpress.com/item/Powe...d-of-small-parts-Free-shipping/903957168.html. 

This one looks the same and is more expensive but the listing has good examples of lamp mounting which is exactly what ive scribbled up. http://www.aliexpress.com/item/Free-Shipping-Reflector-For-1-10KW-Search-Light/1175534552.html Dont really know why that 2nd one is twice the price!

Very tempted to order the $150 one...


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## stuartsjg (Feb 9, 2014)

Ok, got things uploaded this evening, pix and videos of things so far.





http://flic.kr/p/jVs1Fi




http://flic.kr/p/jVrfUx




http://flic.kr/p/jVtMsm




http://flic.kr/p/jVrh46 





Sorry about the strobe in the video. Was on the camera phone and its shutter speed must have been crazy due to the brightness causing it to capture sometimes light and sometimes dark depending on the AC cycle.

Will try video camera next time as ive more control over that.


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## get-lit (Feb 9, 2014)

You would benefit by reading up more on these things in the forums...



stuartsjg said:


> Hi, Thanks for the welome. Have been reading the threads for the last few months and much of the lamp mounting appears to be personal preference and how it fits with your construction.



Incorrect, I myself have posted extensive lamp orientation testing strictly for performance which actually revealed a more complicated construction with more difficult air flow cooling to suite the orientation was most definitely worth the gains. Hint: Go Axial.



stuartsjg said:


> Ive two reflector options, the 18" reflector from Edmund Optics or one from Aliexpress for use with Xenon searchlights



The Edmund Optics reflectors are good for nothing experimental toys for kids to cook hotdogs in the sun. I have one. Absolutely worthless. Without getting into details because this has been covered exhaustively.. size does matter, but so does accuracy, reflectance, and surface quality. A small 4" diameter true optic reflector would outperform the 18" Edmund Optics toy because the Edmund Optics has a useless inaccurate, dull, hazy, low reflectance surface. Plus the Edmund Optics is just aluminum. It will blacken within an hour with the 1200 HMI. Maybe you can keep polishing it out but it's not worth the work and lack performance. I'm not sure about the other one you mentioned but for $150, you won't be out much if it's not any good. Problem is you won't know if it's any good or not because it sounds like you've ruled out the real thing from Phoenix Electroformed, NiPro, and Optiforms. I too have tried saving a buck on the reflector, but found that it's just not worth sacrificing the performance and durability. This is a major component, like the transmission of race car. Don't dump everything into the engine and bolt it up to an S-10 transmission.


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## get-lit (Feb 9, 2014)

I just watched the video -- YOU ARE NOT USING ANY SKIN PROTECTION AND GETTING EXPOSED TO VERY DANGEROUS LEVELS OF UV!!! THIS IS NOT JUST A SUNTAN BOOTH, IT'S UNFILTERED UVB AND UVA! I PRAY YOU ARE AT LEAST WEARING WELDER'S GOGGLES.................... GET A PRESCRIPTION OINTMENT FOR ARC EYE IMMEDIATELY.. AND THE EXPLOSION HAZARD! 

EDIT - I can't tell but that left lead does not appear to be HV wire.. Definitely not rated to at least 30KV, probably at least 50KV for that arc gap. You could die before having to worry about going blind, getting skin cancer, or even before getting the grenade treatment.

--- No Cooling????????? You've managed to pull off everything you are supposed to NOT do, and all at once. Hate to come down hard on you, but wow. Can't have this one on my conscience - never saw any of this

Admin - There really needs to be sticky thread for safety


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## stuartsjg (Feb 10, 2014)

Hi,

i had actaully only been able to find very little on lamp orientation, perhaps i hadnt gone back far enough in the search results. Will certainly have a look through yours as thats one of the remaining areas which i was beginning to attribue to the black arts!

I had seen in general bad reviews of the edmunds kit here, but it was going to be perhaps a means to an end really - something being better than nothing. The heat did worry me with it being such a thin material and just being polished aluminium with no "proper" reflective coating. Will take advise and save my pennies for something better!

On getting a proper electroformed reflector, there are few electroforming companies in the UK and they are concidderably more expensive than US ones. With international shipping, US ones are still cheaper but often are not easy to get as some companies dont like dealing with indivisuals outside their country. That said, ive not got in touch specifically to ask.

On the safley. Fully hear what your saying and i agree a sticky saftey thread from the top folk on here would be really good.

I am a degree qualified electrical engineer and barring the on/off right hand (which went into pocket) was wearing standard MMA welding gear which i have for that purpose. Interestingly, with the mask having a reasonably weak glass for low power welding, i could still hardly see anything of the lamp!

My biggest concern with the lamp was explosion during its first ever run. Also, being ebay, i was never sure of its exact herriatage, how it had been handled etc. Again, thats were i was working on the basis that with the MMA saftey gear on, i should be OK should the worst happen.

On the UV, i have suffered from welders eye due to youth and ignorance with the DIY carbon arc. 3-4 days of feeling like you had sand in the eyes is not at all fun and not at all to be repeatted.

With the HV, its only a cold strike ignotor giving 4-5kV. I wasnt even sure if it would strike the lamp as its spec if for 4.5kV minimum. The ignotor is designed to keep the N-E voltage below the rating of the N and L-ballast cables, these cables going into the ignotor are just standard PVC cables probably rated to 600/1000V. The only risk of flash over would have been if the N PVC cable came to close to the HV terminal. The white HV lead is insulated to suit by the manufacturer. That said, its quite normal to do a 5kV flash test on equipment with cables rated to 600/1000V so standard tri-rated switchgear cable should handle 5kV for the time it needs to.

Cooling, spec of the lamp is for convection cooling, although i would assume that includes a base/mount which acts to disspate the heat. Already stared to buid a proper lamp mount with decent surface areas to keep the seals/ends cool. 

I have some themocouples for use with live bus-bars so they are electrically insulated, next run im tempeted to get them onto the neutral side of the lamp to see what temperature they are running too. Ive access to a thermal imaging camera but i think it will get blinded by the radiant from the lamp so i may not see the base.

Most of the discussion in the Osram guide book implies lamp life and saftey limits are heavily reliant on seal temperature. Below 350C (or 450C if rated) you are OK and can probably run to 125% running hours. At or above rated then you are risking failure within 50% of lamp hours.

Next lamp run wont be untill things are a bit more enclosed and sorted out, i know everything works/strikes and thats enough for now.

Will be back once ive worked out this lamp position, think ill order the $150 reflector, looks to be a coated glass with first surface reflectance, could be rhodium perhaps?

Cheers,
Stuart


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## Mr. Tone (Feb 10, 2014)

Have you looked or inquired here about options/prices? http://www.phoenixelectroforms.com/


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## get-lit (Feb 16, 2014)

I'm very relieved to know you had a well enough understanding to take safety precautions. Xenon lamps put out UV comparable to welding, but Mercury based output 7.5 times as much UV as Xenon per watt. A 500W Xenon lamp outputs dangerous amount of UV, and a 1200 HMI outputs UV equivalent to a 9,000 Watt Xenon lamp.

What's most significant that I forgot to mention is these lamps produce UV-C light, which is the by far the most dangerous UV band. It's germicidal UV, killing living things by breaking down tissue immediately upon exposure, it's also the most blinding and carcinogenic UV band. Fortunately UV-C from the sun is completely filtered by the atmosphere, but UV-C from these lamps is not filtered. Fortunately you did take precautions as you said.

Had you not put your exposed wrist in your pocket, even a short exposure would have burned you pretty badly, starting with itching and redness a few hours after exposure, the next day you wouldn't be able to touch your skin. Another problem is the skin reaction occurs AFTER exposure, and there is no indication during exposure of what you're about to experience.

Typically a #10 welders mask is suitable, but the HMI lamp I see that you are using has a relatively long arc, not really a short arc at all, and therefore the luminous intensity may not be high enough for a typical #10 mask.

I also forgot to mention, the UV output also contains frequencies that produce ozone. A 1200 HMI absolutely MUST BE OPERATED OUTDOORS ONLY, even for short runs.

Again regarding the Edmunds, it's not going to help you at all. Even if you were able to achieve a highly polished surface, the intense UV light quickly breaks down bare aluminum.

You also would benefit with a short arc version of the lamp. I recommend the Philips MSR Gold series. Look at the arc gap versus output, there is one lamp in particular in the series that is fairly good. The MSR Gold also have the highest pinch temp capability (500C) for easier cooling.

Good luck and keep it safe.


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## nealitc (Apr 13, 2014)

I have a few TVS-3 hulks (no bulb or coolant pump) with 30" reflectors that this could fit in easily! They need to find new good homes...


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## Optiforms_Todd (May 6, 2014)

Glad to here we are the real thing! I don't see the full dimensions, but its definitely more than $225 for one of ours of that diameter. You get what you pay for still stands true. We typically achieve 10 wave @635nm surface accuracy with an 80/50 scratch dig or better for surface quality, didn't see the others specs on these.


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## korbi (Dec 17, 2018)

> I also bought a 1200w "faulty" ballast unit from eBay. (Google " Strand Lighting QuartzColor 1200w Compact Daylight HMI / MSR Ballast (magnetic ballast. Model: 2077." and it should come up)
> 
> Also got a Vagnini & Wilson IGK 06 1800w Ignitor, eBay too.
> 
> Hooked up lamp and ignitor and it fired up first time with no drama.



Hi Stuart, nice to know you got it running! How did you manage to have the ballast interact with the ignitor? Don't these ballasts have an extra cable/pin for the ignitor to function? And what about the safe on-circuit... did you just short it? Curious to know!


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## nbp (Dec 17, 2018)

Welcome korbi!

The OP hasn't logged in for two years, but I approved your post in the event that he has notifications turned on for this thread.


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