Brand spankin' new kit from B&H (the "Interview lighting kit" (http://www.bhphotovideo.com/c/product/300828-REG/Lowel_401450_Interview_3_Light_Kit.html): 2 Omnis, 1 Tota) and already my Omnis have burned through four bulbs in less than two hours of usage.

I made darn sure not to touch the bulbs with my fingers during installation, and that they were seated properly. They blew within roughly 20 minutes of striking. One blew right after I changed from spot to flood, but the other three bulbs blew spontaneously, no one was even near them.

This happened in two different locations, so I can't say for certain if the location wiring is the culprit.

These are 500w bulbs and at a cost of ~$25.00 each, this is getting bloody expensive! I've lost two days of shooting because of this. I'm almost at the point of tying them to a trebuchet and launching them into the St-Laurant, tabernac!

Has anyone else had this problem from their Omni lights? Do I have a bad batch?

you got bad bulbs period, or you have really hot line voltage ( unlikely ). I'd call lowel and get the bulbs replaced, and you should not be paying $25 for a lowel bulb, they should be around $15. bulbtronics.com is pretty much the wholesale supplier even B&H gets their bulbs from.

The historic problem with Omnis is that the bulbs mount laterally in the fixture, which means that if you happen to operate them with the fixture and thus the bulb upside down, they will burn up prematurely. So it's a good plan not to do this...

you got bad bulbs period, or you have really hot line voltage ( unlikely ).

I bought the bulbs from two different vendors. The first two I bought from B&H, the second from Solotech (in Montreal). So I'm not sure about the bad bulb theory, unless my luck is really that bad!

I'd call lowel and get the bulbs replaced, and you should not be paying $25 for a lowel bulb, they should be around $15. bulbtronics.com is pretty much the wholesale supplier even B&H gets their bulbs from.

B&H, Solotech and Video Service Ltee all sell the FTK (500w) lamps for about $21.00 (plus tax), which appears to be the going rate for an FTK lamp AFAIK. Though I do see that bulbtronics.com does sell for $12.50 USD...

Getting back to the problem at hand, what could be the problem? And what can I do in the meantime? I have to continue with the shoot tomorrow (after making the trek to get replacements), otherwise I am getting dangerously close to not making the delivery in time for the DVD's replication. I am on a tight deadline and am getting close to both angry and worried. If voltage may be the problem, how can I go about finding out if that is it? Would running my lights off a power strip (*shudder*) be a way to protect the lamps from blowing?

The historic problem with Omnis is that the bulbs mount laterally in the fixture, which means that if you happen to operate them with the fixture and thus the bulb upside down, they will burn up prematurely. So it's a good plan not to do this...

Indeed, and the fixtures were upright at all times. I have been taking every precaution to make sure that they are handled correctly, and I still get lamps blowing out...

My Tota lamp is going nice and strong, on the other hand. No issues there.

Cluck cluck. Sorry to hear about your issues Mike. The Omnis are long known to be the dog of the Lowel line due to their burnout legacy. Certainly the Totas (and the DP's) do work better. I used a Tota as a worklight through a long house renovation, actually had it outside last night during a rainstorm so the contractor could see, the thing just won't die on me!

Cluck cluck. Sorry to hear about your issues Mike. The Omnis are long known to be the dog of the Lowel line due to their burnout legacy.

So they do have a reputation for this? It's not just me?

Well, I haven't heard anything for a long time (haven't USED them in a long time myself) but they don't appear to have changed much...always a flawed design. I'm sure some will chip in and say they have never had issues but who knows...

Another source for lamps (bulbs) is bulbconnection.com

They sell the Osram FTK for $12.50. I have had excellent personalized service as well from this company when I was trying to locate special lamps.

Regarding the omnis, I have used them off and on (I have several) and have not had a problem, so I can't say what your problem is. But when I've used the omnis I've run then for several hours at a time, both on a celing bar and and on stands, with barn doors and clothes pins holding filters, and haven't had a lamp blow. There must be a special issue, either with the lights or the power in your case.

I think it would be worth using a power strip with a surge protector to eliminate that possibility. You can also check the voltage of the power of a volt meter.

However, I can highly suggest calling Lowel and talking to them about the problem. If there is a known issue at all, they will be able to help you. I have called lowel several times and always got excellent, straight advice and/or help.

(I can also attest to the virtual indestructability of the Totas, though this is not a help regarding your problems with the omnis.)

I have had a pro light blow out lamps several times at the slightest jiggle of the light after running 5 minutes or so.

Brand spankin' new kit from B&H (the "Interview lighting kit" (http://www.bhphotovideo.com/c/product/300828-REG/Lowel_401450_Interview_3_Light_Kit.html): 2 Omnis, 1 Tota) and already my Omnis have burned through four bulbs in less than two hours of usage. <CLIP>

These are 500w bulbs and at a cost of ~$25.00 each, this is getting bloody expensive! <CLIP>



Hi Mike,

While I normally use my Totas for 500+watts, the Omni should accomodate 500 watts used properly. As others suggested, the Omni should be operated with lamp filament horizontal. And of course the ventilation should be unobstructed (hopefully not the narrow snout w/500 watt bulb), careful not to move the Omni until the bulbs cool down, no excessive voltage, etc. In fact, until I could figure this out I'd put dimmers inline and turn down the voltage 20 percent - that should certainly add to the bulbs life without messing up your color temperature.

http://www.lowel.com/download/Omni-light.pdf

Good luck, Michael

Yep. The guys are right.

I work as a news photog, and I have a double Omni kit I use every day outdoors for a couple of hours. I carry it with me all day. The truth is, the little blighters pop ALL THE TIME.
I get a blown bulb every week and a half, and that is over me being absolutely ridiculous about my behaviors around them. I have deep, deep protocols for bulb life, and it doesn't help.

I never:
1. Move them lit. EVER!
2. Never move them after lit for at least one minute to properly cool. Or, you've probably halved their lifespan.
3. Never WANT to move them if you can let them cool to the touch on the casing.
4. Never put a cable, or anything near them that might bump. Otherwise, a foot tap on the light stand (I am not kidding, a FOOT TAP, happened to me) will blow them.
5. BE VERY, VERY CAREFUL ABOUT YOUR FOCUS ADJUSTMENT. Even looking at it funny can cause your light to get scared and blow. DO YOUR FOCUS ADJUSTMENT SLOOOOOOWLY. No excitable movements.

Good luck man.

Now, on the other hand, Omnis can kick the light out. Really pump it up. I need that. I am lighting buildings at night, without HMIs.

Still, if you can, get Arri fresnels. If you can't sell the Omnis on eBay and get some DP lights. They're better.

Hi Mike,

the Omni should be operated with lamp filament horizontal. And of course the ventilation should be unobstructed (hopefully not the narrow snout w/500 watt bulb),

That's it!

Never, ever, ever buy an omni bulb that is cylindrical. Get the big, round ones. Never the skinny ones. NEVER!

Also, are you using your safety guard? Must use that if there is no barrier. You need that. They blow hot glass.

Also, look up 600W Impact dimmers. They're 25USD. They'll help you with lifespan, and you can get away from stopping out your lights with gels.

Getting back to the problem at hand, what could be the problem? And what can I do in the meantime? I have to continue with the shoot tomorrow (after making the trek to get replacements), otherwise I am getting dangerously close to not making the delivery in time for the DVD's replication. I am on a tight deadline and am getting close to both angry and worried. If voltage may be the problem, how can I go about finding out if that is it? Would running my lights off a power strip (*shudder*) be a way to protect the lamps from blowing?

That's fine. It won't stop the blow with the power strip. The heat/glass structure is the issue. I always use a power strip, but I am attached to a generated live truck, so the air compressor kicks, and kaboom. Get a 'power squid,' they're a ton easier than a strip for moving around, because a strip twists, and the individual cords help stop tipping.

I would, if I had space in the car, keep some diffusion, and some quartz worklights around, they're cheap. You can buy them at the 'home depot' store in your area. Keep in mind, background lighting in a pinch can be done with those, and if you get a blown light, you can run to the car, and just explain that you got a bad batch of bulbs to the client, and tell them that you're 'changing your light kit as soon as you can for full reliability, and that you're always "a step ahead at solving all of the problems." Stress future reliability. Stress that you always have a workaround, with a positive attitude.

I've always said, "You could sledgehammer my gear, and as long as the camera is fine, by God, come hell or high water, I will get you everything you need."
That gives them a laugh, and makes them feel better.

Diffuse them well.
For clients, defuse them well.

My light kit includes three DPs, two Omni's and a Tota. (I have a seperate fresnel kit).

I know it doesn't help, but I'v had no problems with my omni's. LONG interviews of over two hours, rock solid.

I get my bulbs from Top Bulb, but I don't think I pay more than 15.oo for them. And yeah, they are the 'roundish' bulbs.

Never, ever, ever buy an omni bulb that is cylindrical. Get the big, round ones. Never the skinny ones. NEVER!

What would be the part # for those? Anyone know offhand? The ones I have been using are FTKs and they are indeed cylindrical.

Also, are you using your safety guard?
Indeed, I am.

Also, look up 600W Impact dimmers. They're 25USD. They'll help you with lifespan, and you can get away from stopping out your lights with gels.
I'll check those out as well.

At times I am thankful for this online community, at other times I am really thankful for this online community!

There must be a special issue, either with the lights or the power in your case.

I think it would be worth using a power strip with a surge protector to eliminate that possibility. You can also check the voltage of the power of a volt meter.


I have a volt meter, but I never really learned how to use it (silly, isn't it?). There are so many different settings and guages, i have no idea what I am looking at. ;-}p

Also, look up 600W Impact dimmers. They're 25USD. They'll help you with lifespan, and you can get away from stopping out your lights with gels.

I looked them up, (http://www.bhphotovideo.com/c/product/283607-REG/Impact_D600_Dimmer_Control.html) however they only have 2 prongs? Is that right?

Alex is right about never moving the things lit. FWIW, ProLIghts are the same way, or should I say the bulbs are. One little tap on the light stand will kill the bulb. great little light with a 125W bulb, but not reliable. I've run a couple of DP lights for years with 500 and 1K bulbs and have yet to burn a bulb out, even when adjust the light when lit. sounds like nothing more the the wrong bulbs.

when I was talking about voltage, I meant get a voltmeter and carefully plug it into the the wall at the appropriate setting and see whats coming out. usually its around 117V here, and in summer it may drop to 110. I was thinking maybe you where getting 125 or something, and the bulbs you had gotten where 110 rated. always better to run a bulb 10% under then over ! read the specs for the bulbs you got, which may account for the difference in design. there are 130V consumer bulbs out there, mainly for use in places where changing a bulb is a PITA. in pro bulbs, there can be differences too. 110V bulb run at 120V puts out more light then a 120V bulb of the same wattage. the trade off is shorter life and more sensitivity to vibration failure.
FWIW the omni's I've used have have the spherical bulbs and have not been a problem.

I've had an Omni for many years and never had any problems with bulbs dying early. You might take a close look and make sure the bulb isn't touching the reflector when it's zoomed in or out. I remember one time after an airplane trip where the lights were checked in cases, I noticed the reflector seemed to be touching or almost touching the bulb, and I applied some force to get things back to normal. You might also take it apart and make sure there's not something loose.

One other thing, a long time ago I bought some cheaper brand of bulbs for my DP lights, and I liked them at first because they were so easy to insert and pull out. Turns out that was a bad thing. The posts were too thin, and that was causing arcing and burning out not only the bulbs but frying the sockets too. I had to replace all the sockets. I went back to Sylvania and never had a problem again. Take a look at the socket and see if you see any evidence of charring; that could indicate arcing.

when I was talking about voltage, I meant get a voltmeter and carefully plug it into the the wall at the appropriate setting and see whats coming out.

That's what I'm trying ti figure out. Amongst ACV I have three settings: 15, 150, 500 up. I would guess 150 is the right setting?

I can't seem to find them, but the big fat round ones, are in my remembrance, the Ushio ones.

Good luck man.

That's what I'm trying ti figure out. Amongst ACV I have three settings: 15, 150, 500 up. I would guess 150 is the right setting?

Yes, that's the correct setting. You could also put it on 500 but it won't be as accurate. Just use a setting that's higher than the voltage you expect to be reading. The best accuracy with voltmeters is when they are operated in the upper 1/3 of their measurement scale.

It's highly unlikely that the voltage being supplied from the wall outlet is excessive. Under peak demand, the voltage can and does sag a few volts, but I've never seen a steady over voltage condition from the power company.

-gb-

That's what I'm trying ti figure out. Amongst ACV I have three settings: 15, 150, 500 up. I would guess 150 is the right setting?

OK, it appears that -- if I measured correctly -- I am getting between 125 and 130 volts.

It's highly unlikely that the voltage being supplied from the wall outlet is excessive. Under peak demand, the voltage can and does sag a few volts, but I've never seen a steady over voltage condition from the power company.

Well, the location (my loft) is in what used to be a boot and shoe factory. It's fairly old and the electrical work in the place looks like it was done by HR Giger himself. I don't know if that's a factor or not.

I should mention that all the lamps I have for Totas are the round ones, not the cylindrical. As I said above, I haven't had any go out.

Some of the round ones are:
EKB 420 watt OSRAM & GE have the round bulb
DYS 600 watt (obviously above the 500 watt omni, but the same base)

In the FTK the OSRAM brand is "more round" than the other brands, but not fully round like the ones I list above.

I don't know if this shape makes a difference or not.

the voltage should be constant unless you know there is some big gear switching on/off, summer cooling loads, ect. if you are getting different readings at different outlets, its cruddy wiring, or a transformer not putting out the same voltage on the same legs. in either event, you should not be going over 120V. getting 125, certainly 130V is grounds to call the power company and complain. in an industrial space, where heavy loads where expected, but no longer there, this is almost to be expected the voltage is a little up to compensate when loads are placed on the line.

barring the power company doing some work, the simple fix is get some dimmers and run the bulbs at 120 or 115V. minor change in color temp, but your bulbs will last, especially if you have gotten 110V-ish rate bulbs. 20V over won't do them well.

OK, it appears that -- if I measured correctly -- I am getting between 125 and 130 volts.

Rehi,

Assuming your meter is reading correctly (hopefully on the 150VAC scale which is more accurate), then indeed you've found the smoking gun!

Next take your voltmeter and validate its accuracy at your home, in a commercial building, etc. The RMS voltage in the U.S. should not exceed 117VAC. As we've stated, a hotter voltage will greatly diminsh the life of your bulbs.

Many of us use Harbor Freight Router speed controllers to vary down voltage to our lights (good for up to 1500 watts):

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=43060

Good luck, Michael

Assuming your meter is reading correctly (hopefully on the 150VAC scale which is more accurate), then indeed you've found the smoking gun!

Indeed, it was using the 150VAC scale. It stays at a constant voltage, just in between the 125 and 130 hash mark.

AFAIK, Canada and the US use the same voltage standards. The building my loft (which is both my living space and my studio) is in used to be a boot and shoe factory. It hasn't undergone any really renovation... it isn't one of those trendy upscale lofts, it is very stripped down, former industrial space that had some walls thrown up and minor plumbing to add a toilet, sink and shower. I should upload a picture of the electrical breaker box in my space... you'd see what I mean by the Giger reference!

Many of us use Harbor Freight Router speed controllers to vary down voltage to our lights

Interesting. Much cheaper than the Impact dimmer from B&H. I like the fact that it has a grounded plug. Thanks for the tip!

Mike,

For those living in cold weather climates (under 50 degrees), using a dimmer has another benefit. Rather than blasting a cold tungsten filament with instant heat, instead bring each cold bulb to temperature by slowly turning up the dimmer (20 percent - pause, 40 percent - pause, etc). Luckily, living here in California and working inside this hasn't been much of a problem for me but I suspect some of our cold weather friends out East has some war stories to tell.

Regards, Michael

I found this thread interesting...

I travel with a Lowel Omni/Tota kit all the time - it's probably 10 years old by now - buy bulbs wherever I find them cheap - move the lights while on, and I very, very rarely have bulbs burn out prematurely.

The one time I had a bulb burn out in an Omni it was due to a short when I adjusted the throw of the beam - and for some reason that shorted out the bulb. I replaced the reflector and hadn't had the same thing happen for maybe 4 years now...

The one thing that broke was the lock on the right side - TSA must have been a little hard on it as the case was OK when checked at the airport and when I picked it up the lever was broken off..

If anyone know where I can get a replacement, let me know, please...=*^)

Getting back to your problems - I think you must have some fluctuating current in your building - try to run it thru a "clean power" thingamajingy...

Christer

Just to chime in, I've use the same Omni in every major city in the US, across Canada and even in Mexico. Never a problem. We use the Oshram bulbs from Lowel and zero problems. Now the Pro Light with GCA's (250W) really need to be handled delicately, in fact, they don't ship with GCA's anymore, they now recommend the FVL (200W). A little less wattage, but much better lifespan.
We sell a couple Lowel DV Creator Kits per month and rarely hear of any issues besides the Pro Lights with GCA's.

Not being able to find a suitable dimmer/voltage controller locally (neither one meant for lights, nor something like the router controller... local because I can't wait for a shipment nor can afford to pay for next day service from US) I decided to employ my wits and feeble electrical skills (ok, my wits are pretty feeble too). Keep in mind what I am about to describ is my intended solution for Omni lights using FTK (that's 500w/120v, kids!) lamps.

My materials:
• Two sliding light dimmers rated for 600w (with a switched off position at the bottom)
• Two enclosures
• Two 5-foot 16-guage extension cords

Where I am going with this should be obvious: I cut an extension cord in two and connect the pieces to the sliding dimmer in order to make my own death trap... I mean, inline dimmer control.

I plugged it in and put my voltage meter on it. With the dimmer in the "off" position, I have no voltage registering. I switch it on, and I have the expected ~130v I get straight from the wall. What I am not getting is an expected change in voltage as I manipulate the dimmer. It keeps at a constant voltage.

Befuddled, I moved on to a real world test by testing my contraption on my cheap table lamp. In the "off" position the lamp is off. When I switch it on and manipulate the dimmer, I see expected results: the light dims with the setting of the dimmer. (Uh, I also blew the 40w/120v bulb when I pushed the dimmer up to 100%.)

So, it appears I do not have a voltage controller. I have no idea what I have, other than a waste of $$$ and resources. What could I have done wrong?

Many of us use Harbor Freight Router speed controllers to vary down voltage to our lights (good for up to 1500 watts)

Can you, or anyone else who has one, confirm that it actually reduces the voltage coming out? I ask because I was talking with someone at the local hardware store who told me there is no way to control the voltage, other than by calling in Quebec Hydro. I need to literally reduce voltage, and my contraption (see post #32) is not doing the job.

I can't remember how much I've forgotten about this stuff since college, so I may be full of Sh--, but, saying voltage reduction can't be done except by the power company is BS.

I may be 1000% wrong, here but I think what you need to really reduce voltage is a variable transformer or Variac of some kind. I think the router speed controllers do their thing by dropping some of the AC cycles electronically, thus reducing the total power available in unit time. Which should also reduce your light output OK but not sure it will really do it by changing the voltage.

I think the household dimmers are more like variable resistors that just add some electrical load to the circuit. They can get quite hot in the process.

Damn, but I wish I could remember this stuff better. You'd never think I was once a Chemistry & Physics major - but then again it was almost 50 years ago.

Oh well, as they say, education is what's left after you forget every fact you learned in college.

Edit 1: OK - I found a readable link hat helps explain all this.

http://www.epanorama.net/documents/lights/lightdimmer.html#basics

It seems that in the 50 years since I was in college dimmers have gotten smarter and they also seem to work to reduce power rather than just add a resistive load or directly reduce voltage. As the gentleman says in the linked article, the components used today were not in existence when I was in school.

To net it out, these gadgets don't reduce voltage, they cut off power for some part of the cycle and in a sense increase percentage of the cycle where there is no current flowing.

Here's a quote from the link
_______________________Quote___________________\
Some light dimmer history

Light dimming is based on adjusting the voltage which gets to the lamp. Light dimming has been possible for many decades by using adjustable power resistors and adjustable transformers. Those methods have been used in movie theatres, stages and other public places. The problem of those light controlling methods have been that they are big, expensive, have poor efficiency and they are hard to control from remote location.

The power electronics have proceeded quickly since 1960. Between 1960-1970 thyristors and triacs came to market. Using those components it was quite easy to make small and inexpensive light dimmers which have good efficiency. Electronics controlling also made possible to make them easily controllable from remote location. This type of electronic light dimmers became available after 1970 and are nowadays used in very many locations like homes, restaurants, conference rooms and in stage lighting.

How modern light dimmers work ?

Solid-state light dimmers work by varying the "duty cycle" (on/off time) of the full AC voltage that is applied to the lights being controlled. For example, if the voltage is applied for only half of each AC cycle, the light bulb will appear to be much less bright than when it get the full AC voltage, because it get's less power to heat the filament. Solid-state dimmers use the brightness knob setting to determine at what point in each voltage cycle to switch the light on and off.

Typical light dimmers are built using thyristors and the exact time when the thyristor is triggered relative to the zero crossings of the AC power is used to determine the power level. When the the thyristor is triggered it keeps conducting until the current passing though it goes to zero (exactly at the next zero crossing if the load is purely resistive, like light bulb). By changing the phase at which you trigger the triac you change the duty cycle and therefore the brightness of the light.

Here is an example of normal AC power you get from the receptacle (the picture should look like sine wave):
... ...
. . . .
. . . .
------------------------------------ 0V
. . . .
. . . .
... ...
And here is what gets to the light bulb when the dimmer fires the triac on in the middle of AC phase:
... ...
| . | .
| . | .
------------------------------------ 0V
| . | .
| . | .
... ...
As you can see, by varying the turn-on point, the amount of power getting to the bulb is adjustable, and hence the light output can be controlled.

The advantage of thyristors over simple variable resistors is that they (ideally) dissipate very little power as they are either fully on or fully off. Typically thyristor causes voltage drop of 1-1.5 V when it passes the load current.

Edit 2: By the way, the little drawings look the same because the forum software seems to have dropped some blank spaces.

I can't remember how much I've forgotten about this stuff since college, so I may be full of Sh--, but, saying voltage reduction can't be done except by the power company is BS.

That's what i thought too... I mean, there's got to be a way... it's not rocket science, it's just voltage! And if I can build a DIY ring modulator or analogue synth (which uses small voltage controllers all over the place) then I should be able to rig something that can handle this load.

I think the household dimmers are more like variable resistors that just add some electrical load to the circuit.

And thus we reach the limits of my electrical understanding. I know just enough to know -- or at least think -- that i want to have a variable resistor (like a pot of some kind... yeah, like on my electric guitar, eh!) to add resistance in order to bring the voltage down. That's how I thought this stuff works... but this is all from learning on my own, and not necessarily well...

I am seriously doubting the ability to get this thing in the can within the next six days... unless I can get shooting done by Monday, I'm screwed. The budget is practically blown as it is. [insert string of profanity here]

I think all is not lost! (By the way, I added an edit to the previous post that explains it a little better)

I think any place that sells motors etc can aim you at some place to get a voltage reducer/variac etc. And I think the woodworkers supply places can also aim you at such hardware or may even sell it themselves. I bought my single phase to 3 phase converter from an industrial woodworking supply shop.

I suspect they would sell router speed controls etc as well. These things aren't tremendously expensive as I recall.

I think the woodworkers supply places can also aim you at such hardware or may even sell it themselves.

I hope so... the people at Home Despot didn't have a clue as to what I was asking for until the third time i explained it. All they said was that they don't carry it... which surprised me, you'd think a place like that would! So far none of the hardware shops I've been to had it or knew where to get it.

I wouldn't waste time in a hardware store - they're really unlikely to have anything useful. What you want is a commercial machinery place or a commerical or even advanced hobbyist woodworking or maybe even metal working store.

I Googled around and cmae up wih a couple of woodworking supply places in Montral

If I were you I'd call these guys or a similar place and ask about a router speed control or a variable transformer - I'm sure they'd know what you were talking about and be able to aim you in the right direction.

http://superpages.ca/bus/Quebec/Montreal/Chas-Gentmantel-Fils/2175849.html?adid=01435600

http://www.rr-motors.com/

Or call harbour freight or woodcraft supply in the US and get them to FedEx you one overnight The one on harbour Freight was $10 and I doubt it would be very expensive to ship it.

Only one caution - these speed controls reduce power, not voltage per se. A variable transformer on the other hand will reduce the voltage.

One other thought - call an electrician and tell him you have an overvoltage problem and are blowing out equipment. Or call the electric company and explain your problem and ask them what they can recommend.

One more thought - the voltage regulators/battery backup units made for PC's may do the trick - I have a couple that are rated for 1500W and will boost low voltage/drop high voltage on the fly. Maybe a little pricier than some other option, but any reasonable sized computer store should have a couple of APC 1500W units around. In fact I've even seen them at Office Depot, Office Max etc. Some hot PC's pull 600W or so, so a couple of lights should be a piece of cake.

here is what I can tell you about Omni's

We ran multiple Omni kits for years using only DYS 600 watt lamps.

I have rebuilt way too many of these fixtures

We always pull off the UL required safety wire screen. It holds in too much heat and causes both lamp failure as wel as refector failure.

we found out that Osram lamps have a smaller glass globe surrounding the element. on long strikes, the element wanders around inside and often come into contact with the glass, which causes lamp element to blow.

We only use USHIO for our DYS lamps because they have a very large glass globe surrounding the element. This has greatly increased lamp life.

hope this helps

We ran multiple Omni kits for years using only DYS 600 watt lamps.

Funny, I was just looking at those and wondering "hmmm, technically 100w over the stated limit, but rated for 125v... I wonder if I could get away with that?" when the notification of your post came in!

Just to make sure, is this (http://www.bulbconnection.com/ViewItem/bcrw/itmid/1018/oc/DYS%2D5%20%28DYS%2F5%29/item.html) what you've been using?

One thing I notice right away, and it may not matter at all but I need to ask, is that the base type for these are GZ9.5 (2-Pin Prefocus)... the base type for the FTK lamps I have are GY9.5 (2-Pin Prefocus)... close, but not exact... does it matter?

yes that is what we use DYS, one pin larger than the other. see the larger globe size.

Rehi all,

Forgive me for getting into the esoteric stuff - I wanted to clear up the misconception about gated dimmers. As we previously mentioned, our voltage in the United States in 117 volts alternating current at 60 hertz. Now then the 117vac is based in RMS (Root Mean Square) as opposed to the peak or average voltage - not that it really matters much to us for day to day stuff.

But when we use a gated (thyristor-based) dimmer, it reduces the peak of the sinusoidal 117vac wave form - no more RMS. This means the load, the Lowel Omni in our case has a lower applied voltage. Certainly the tungsten resistive load doesn't change and the current going through the bulb is predicated on the applied voltage. Incidentally, power is just another way to measure the current x voltage.

Bottom line, reducing the dimmer (of any type) means the bulb doesn't get as much heat applied to it, lasting a longer time. Again, I've found the Harbor Freight router speed controllers work great.

Okay? Michael

That's great to hear, I ordered a few myself :)

Forgive me for getting into the esoteric stuff - I wanted to clear up the misconception about gated dimmers

I'm afraid I'm lost... the theory is going way over my head.

[...] when we use a gated (thyristor-based) dimmer, it reduces the peak of the sinusoidal 117vac wave form - no more RMS. This means the load [...] has a lower applied voltage.

But how do I measure that? All I understand is that, regardless of the dimmer position, ~127vac is coming out of the dimmer -- the same as if coming straight from the line. How can I gauge my dimmer position to know where I am reaching an 8% reduction? I need a sense of scale in order for this to be of any practical use.

Michael,

I'm not sure what you mean by "no more RMS", since RMS (Root Mean Square) is just a calculation method that gives us a way to understand the total current from a fluctuating source. I don't think there's anything that requires a sinusoidal waveform in order to have an RMS value. Easy to calculate for a sine wave, though.

As I recall, peak voltage in the US is actually around +/-165 volts which would be equivalent to 117 volts RMS (which as you correctly say is the way AC line voltage is described)

As I understand it, thyristor based dimmers, router controls, etc essentially switch the current on and off quickly so for some period of time the voltage coming out the back end is zero. So the voltage coming out the back end, regardless of its peak value, is no longer sinusoidal. It looks like a sine wave with some gaps in it. The resultant back end (RMS) voltage is lower than the input RMS voltage. Not because the actual peak voltage has changed as much as because the shape of the curve has been changed (to have some periods of zero voltage,) therefore the total power/current in unit time is reduced.

Conceptually I think the gated dimmer/router control, etc is sort of like your kitchen blender - if you keep pulsing the switch on and off the motor never revs up to quite its full speed.

Anyhow, regardless, there are several ways to solve the original problem

1) Bulbs with higher voltage rating

2) Lower average voltage (hence lower temperature) achieved by gating the circuit

3) Lower average voltage caused by lowering the actual peak voltage with a transformer.

4) Other

For resistive loads like a lamp bulb, either 2) or 3) should be fine. For other applications, maybe they're not equivalent.

Mike,

What kind of voltmeter do you have, digital or analog with a needle?

Either way I don't think this is a situation requiring great precision - just crank it down until the bulb looks a little less bright. May not be perfect, but you should be better off

What kind of voltmeter do you have, digital or analog with a needle?

Analog w/ needle.

Either way I don't think this is a situation requiring great precision - just crank it down until the bulb looks a little less bright. May not be perfect, but you should be better off

I don't know... I the kind of guy that aims for precision as much as humanly possible (must have inherited that from my grandfather, a precision optics maker during WWII). There must be a way to scientifically measure and quantify the change that is occurring.

Mike,

I feel for you - I'm the same way.

I'm really puzzled about why the meter isn't showing a voltage drop. If it were digital I could at least invent some plausible (albeit probably wrong) explanation, but old fashioned voltmeters should show the difference I think.

Hmmm.

Just a thought, but does the needle flick back and forth a bit at what seems close to a consistent 60 Hz? Does it show 0 when the dimmer is at minimum setting?

What brand is the dimmer? I'll go to the store in the morning and get one and try to duplicate what you're seeing.

Re how to calibrate:

There are several ways to do it, but not sure you'd have the appropriate equipment.

You could try to catch the difference in color temperature - if the lamp is really running at overvoltage it should have a slightly higher than rated color temperature. Problem is that the difference would be pretty small and the rating is probably only nominal to start with so there would be lamp to lamp variations.

A good exposure meter might catcht the difference, but again we're only talking about a pretty small variation from standard, so the precision/repeatability of the test equipment and test setup would be a big unkown.

Just a thought, but does the needle flick back and forth a bit at what seems close to a consistent 60 Hz? Does it show 0 when the dimmer is at minimum setting?

All along the dimmer's range, it stays constant. The only time it drops to zero is when I click it to the "off" position.

What brand is the dimmer? I'll go to the store in the morning and get one and try to duplicate what you're seeing.

Thank you, but I wouldn't want you to waste your money! What I bought was a Leviton "Decora Sureslide" slide dimmer (part# 6621-W). It's single pole, rated for 600w. It ran me significantly more than the rotating knob dimmers, but I liked the sliders for their control (and I intended to be able to tape a stopping point to make sure I didn't accidentally go over my 117v point... I'm all about those little details). It ran me about $20 CAN each.

I ordered some DYS 600 watt lamps that are rated for 126v, which I hope will get me by. :-/

Hi Mike,

No problem. Now you've got me really curious about what is going on here. I bought a rotary dimmer and I'm going to set up an experiment as follows:

Wire the dimmer into the line with a lamp socket also wired in, and attach the voltmeter as well.

Then I can confirm if the dimmer is dimming the bulb and also showing lower voltage. If the bulb dims and the voltage doesn't shift, then I have a couple of other ideas of what is actually going on that I can follow up on.

Maybe I'll also get a slide dimmer - depends on the outcome of the first set of experiments.