Is there, other than cost, any reason that two lamp T8 5 foot rapid start bulbs in a single fixture could not be able to use a separate electronic ballast for each bulb?
Would there be any strobe type problems or other such problems with this arrangement?

Also what would be the effect of repeated switching on and off of a electronic ballast and a single bulb combination, say only three time each?


The reason I am asking is I am looking to use a two bulb rapid start T8 5 foot fixture using one electronic ballast for each bulb and switching them on and off independently at start up to simulate a magnetic ballast preheat fixture for a reproduction application.
I have the automatic switching arrangement already figured out, but not the effect on the electronic ballast and bulb.

My experience is with magnetic ballasts, but I know very little about electronic ballasts.

Ok so it sounds crazy, but I really need to know.
So I come here to the experts.

Thanks

    

 

Hello Larry, and welcome to Lighting Gallery!  I should have said that earlier when I started seeing you post. 

I am not the best when it comes to ballasts and so forth, but I do know that using an electronic ballast that is Instant Start flashing 2-3 times will really shorten the life of the lamps.  Programmed start electronic ballasts are much better for more frequent switching.  You could use those, but it would be hard to come up with "preheat" startup with those.  Worst case scenario (as much as I would like to make a repo of that RF Westinghouse fixture), I probably would shorten everything porportionally for use with 2 F40T12 lamps, and get a tulamp preheat or 2 single preheat ballasts to have that startup flicker.  Wouldn't be like the real RF Westinghouse fixture though.  Its just a thought.

Hello Larry, and welcome to Lighting Gallery!  I should have said that earlier when I started seeing you post. 

I am not the best when it comes to ballasts and so forth, but I do know that using an electronic ballast that is Instant Start flashing 2-3 times will really shorten the life of the lamps.  Programmed start electronic ballasts are much better for more frequent switching.  You could use those, but it would be hard to come up with "preheat" startup with those.  Worst case scenario (as much as I would like to make a repo of that RF Westinghouse fixture), I probably would shorten everything porportionally for use with 2 F40T12 lamps, and get a tulamp preheat or 2 single preheat ballasts to have that startup flicker.  Wouldn't be like the real RF Westinghouse fixture though.  Its just a thought.

Hello, glad to be here!

Great information and insight.

Yeah I thought of using a scaled down double 40 watt preheat setup also, but like you say it would not be like the original.
It would sure cut manufacturing costs, but in this case cost is not too much of a factor as the target buyer is looking for that something different that no one else has. Kind of a upscale shopper that gets what they want and cost is secondary.

I have a catalog here of upscale antique lighting fixtures for the home that has prices that are out of sight, but they still sell a lot of them. These type of people buy from the catalog because they like the look of the fixture (may be they seen one in Spain or somewhere) and then have an electrician install it for them because they are having a special dinner party next week. A doubt many of these people have ever been in a Home Depot.

I was thinking about making a RF prototype fixture as close as I could to the original to evaluate the labor, material costs and to see if would actually work and most important, what it looks like.

And that is the thing as looks are everything even if not all the visible parts are 100% exact.
What I am saying is that 99.99% of the people out there have never seen one of these in person.
I have actually seen one in person before, so I would know, but most people would not know if it was correct or not.
But that don't mean that it is not well built.

To start out with I would just use two T8 five foot bulbs with the correct ballast and bulb plug ends and wiring for testing.

I would guess that there would be a break point on costs as what number of sheet metal parts made before the costs went down.
If not in quantity of a certain number, I would expect the cost per each unit could be up there for most people, but not for all people.

But finding fixture parts to make patterns out of could be a problem.
Pictures help, but exact dimensions would be required if any reproductions were to be successful.

As far as the preheat rapid start ballasts go, it was just something I was thinking about maybe down the road some time.
It won't be any time soon for sure, I got to get one of these to work first.
So a simple ballast and bulbs for now.
 
Well I know it will light up of course, but how will it look when it does?
 
That is the big question.
Large pieces of sheet metal depending on the gauge can be a little awkward to work with and tend to bend in places you don't want it to bend at.
Some bends can be tricky for even a qualified sheet metal shop.

I would guess that the original reflector was stamped out on a stamp press in one piece like a fender for a car.
Any stamped rounded parts on the top of the unit may end up being square welded corners as metal stamping, while very quick, is expensive to do in small numbers.
This is big $$$ for sure, so it is back to the sheet metal shop.


Lot of questions, not enough answers at this point.


   

 








 


 

Or you could import some 58W T8 ballasts from Europe, but you would have to run them on 240V here in North America. You might also need European starters as I don't know if it would work with standard FS-4 ones. You may be able to find that on eBay. You would need two ballasts for a two lamp fixture (one ballast per lamp ; there is no such a thing as a tulamp ballast for high wattage lamps in Europe.

I second Brendda that your proposal would be very hard on the lamps. The local hospital has bed-top wall lamps with a direct downward part (2xF32T8) and an adjustable indirect/examination part with 2xF32T8 as well. There is one pull chain switch that is 3-way : one pull, only the bottom lamps, next pull, only the top lamps, next pull, all lamps and finally next pull, all lamps off. Since most of the time it is used in an indirect lighting, people pull the chain twice, flashing the bottom lamps in the process. To turn it off, two more pulls, again flashing the bottom lamps. The result : very black ends on the lamps. (I don't know if you follow me here, it is hard to explain).

Or you could import some 58W T8 ballasts from Europe, but you would have to run them on 240V here in North America. You might also need European starters as I don't know if it would work with standard FS-4 ones. You may be able to find that on eBay. You would need two ballasts for a two lamp fixture (one ballast per lamp ; there is no such a thing as a tulamp ballast for high wattage lamps in Europe.

I second Brendda that your proposal would be very hard on the lamps. The local hospital has bed-top wall lamps with a direct downward part (2xF32T8) and an adjustable indirect/examination part with 2xF32T8 as well. There is one pull chain switch that is 3-way : one pull, only the bottom lamps, next pull, only the top lamps, next pull, all lamps and finally next pull, all lamps off. Since most of the time it is used in an indirect lighting, people pull the chain twice, flashing the bottom lamps in the process. To turn it off, two more pulls, again flashing the bottom lamps. The result : very black ends on the lamps. (I don't know if you follow me here, it is hard to explain).

Yeah, I have seen this type of lighting before and see what you are saying when pulling the chain. Without a delay of some sort I could see where the bulb life would be shortened. I agree that pulsing a bulb would shorten the life of the bulb and I would guess the electronic ballast also. Like most here I prefer the magnetic ballasts over the electronic ones. Some of these electronic ones, well the early ones tended to fizzle out early.

The 240 volt thing would be a problem here in the states I am afraid. I have the circuit worked out for making the rapid start ballast act like a preheat ballast on start up, but bulb life could be limited. However in this application is kind of special as bulb life is secondary to the light fixture its self as a reproduction of the original. 

I am open to all suggestions and I have learned so much here as this site is a treasure trove of information about lighting.
I have replaced a lot of Ballasts and lamps over the years, but never really thought much about how they work other than knowing about preheat and rapid start ballasts and their differences.

Just cut off the wires pull out the old ballast and install a new one with some wire nuts and go on to the next one.


 

Re the 240 volt problem, you could use a simple step-up transformer. They abound on eBay. Otherwise, you would have to wire a 240 volt circuit, complete with a double pole switch, if code allows such a thing. Another solution which is very hard to find unless you get very lucky : I think Vossloh Schwabe used to make a European style ballast for 58W lamps that ran an autotransformer off the 120 volt mains. There are none on the eBay.ca site at the moment, but maybe eBay.com. The 58W lamp is/was popular for refrigeration lighting, so you might be able to find some kind of ballast from refrigeration companies.

Re the 240 volt problem, you could use a simple step-up transformer. They abound on eBay. Otherwise, you would have to wire a 240 volt circuit, complete with a double pole switch, if code allows such a thing. Another solution which is very hard to find unless you get very lucky : I think Vossloh Schwabe used to make a European style ballast for 58W lamps that ran an autotransformer off the 120 volt mains. There are none on the eBay.ca site at the moment, but maybe eBay.com. The 58W lamp is/was popular for refrigeration lighting, so you might be able to find some kind of ballast from refrigeration companies.

Well that is a good idea. I have seen 5 foot bulbs used in refrigeration cabinets in stores that use starters, but that has been a long time ago.

May be I will look on Amazon or E bay. The thing is that what ever preheat ballast used, if fixture production was ramped up, there would need to be a steady supply of them or a ballast that would not become obsolete and could not be replaced since this would be a new modern fixture.
I know preheat ballasts are on the way out little by little every year.

I don't want to get in a situation with no spare parts available for a brand new light fixture.
It would have to off the shelf parts available currently anywhere.
Of course that is hard to do now days as everything is in constant change it seems.



   

During frequent switching the reason for the lamp suffering the extra wear is, on most ballasts the arc strike before the electrodes are properly warmed up. When you ensure this condition (a discharge present on cold electrodes) never happen, the lamp won't be limited in ON/OFF cycles (in fact on magnetic ballasts the lamp shut down and ignites every time the current goes through zero, 100/120x per second and yet the lamps survive 10000's hours of such operation...).

If you want "wild  preheat flashing" without actually hurting the lamps, you may use any magnetic ballast and a modified electronic starter based on a fluoractor (S10e from Philips, "pulsestarter",...), or make one by yourself.
The modification is in the way, how you control the preheat (via the small thyristor depicted on the lef in the datasheet "application diagram"). Activating the SCR mean the lamp light, not activating the lamp remains OFF and the heaters supplied.
Now if you let the lamp first preheat for about 1 second (that is normally needed for a glow starter to first close it's contacts), then perform few flashes (activate the small thyristor for a brief times, so the starter will ignite) and then keep it ON (or you may pretend any flashing pattern, like "worn out lamp",...). As the lamp will either light, or have filaments heated externally, the lamp will actually never ignite with cold electrodes, so there will be no sputter wear.

For a ballast you may use any ballaset (but I would prefer lead style magnetic, as that does not overheat by shorted lamp when doing wild flashing effects) for the lamp, you have to check the currents both during preheat (for your effects it should not be above the 1.5x rated lamp current, preferably equal to the rated current).

You may do the same with an electronic, but the effect will have to be directly build into the ballast to control the frequency (higher frequency for lamp OFF/preheating, low frequency for lamp lighting, sweeping from high to low). But that you will have to build yourself. Again, the operation will be either tthe lamp will light, or the filaments will be separately powered, so no cold ignitions.

Thank you for the response.

This is a lot of information to digest, but I do think I understand what you are saying.
It was just an idea I had to simulate a preheat start up using a modern off the shelf electronic ballast.
The reason being that I have been looking into making a prototype 1941 Westinghouse RF florescent fixture to evaluate whether or not it is feasible to go into production making these for sale as a reproduction light fixture.

So I am looking in to all aspects of this from sheet metal bending, ballasts and bulbs.
As you know, these special RF fluorescent fixtures are unique in construction and are one of a kind made for a special situation to turn night into day 24/7 in "blacked out" aircraft plants during the second world war.

It is this special construction of the fixture and its operation that I am trying to recreate so as to be as close to the original fixture and operation as possible.
Of course it would very difficult to actually make one of these as the original was due to the unique mode of operation as the bulb is a mercury rectifier with a phosphor coating and a special ballast with a relay starting system to operate the special bulb that used carbon rods in one end only.
Interesting bulb design.

At the time 1941, it had the highest light output of any other fluorescent fixture due to its special design.
But the design was abandoned after 1942 as better lighting became available.
It is this unique light fixture that I am attempting to recreate using modern materials and off the shelf electrical devices.
I welcome all suggestions as the more I know, the better the chance of success with this project.





   
   

For the special effects it will need special electronic anyway (some microcontroller controlling it,...), so making it as a special "flashing" starter I would see as the easiest way: The custom electronic will be just the starter (so not as complex), the ballast will be then an of-the-shelf (so easy to replace by the user - I guess that is the main reason for your approach) magnetic unit.

Making the effect completely by the of-the-shelf ballasts I see as not feasible, the ballasts won't handle the fast flashing.

For the mimicking of the RF operation, I think you will need to mimic the 60Hz flicker of the individual tubes (each of them light just for one mains polarity and it is dark for the other).
That I see as easiest to achieve using a single RS magnetic ballast, use it with two tubes in series, but add two diodes parallel to each tube with it's cathode towards the common middle connection.
So for one polarity the current flows from the ballast through one of the diodes, to one tube, for the reverse through the second diode and second tube. With that, each of the tube end connected to the ballast will be heated and the same end will act as the cathode.

That is interesting. This may be the way to go.
If production was a few thousand fixtures a year you can see why modern off the shelf components are required for this reproduction to be a success.

Of course I would prefer to use a magnetic ballast, but here in 2014 it really is not practical.
That was then, this is now.
Really there is no other way with this.
 
A off the shelf ballast with a separate device to create the preheat starting effect may be the way to go so it  could be replaced separately from the ballast.
If the preheat starting device fails, you could just wire around it and the fixture would still operate.

Like you say may be a electronic ballast could be reprogramed to create the preheat effect without too much wear on the bulbs.
A regular off the shelf electronic ballast could be offered in the fixture as standard and a optional special preheat effect reprogramed electronic ballast could be ordered with the fixture at a extra cost for really hard core users that are into the preheat experience.

Personally I always liked the preheat starting effect.
I would say that most people today don't even know what a preheat fluorescent light start even looks like.
It would be a selling point.

I guess if someone wanted to they could just order the fixture without the ballast and install their own magnetic ballast preheat set up.
It could be a option at a lesser cost.
It is an idea.

As for the flicker part, while it would be authentic, it could be a problem.
I remember it well from the 50s and early 60s.
Trying to do anything under a flickering fluorescent lamp was cause for real eye strain.
This was one reason people did not care to use them at home to read a book with.
I would like to stay away from that.
  

Probably 99% of the world population could care less about owning a antique fluorescent light fixture.
But if just 1% did, it would be a huge success, 1% of the world population is a lot of people.
Plus for a garage or large shop several would be required.

There are plenty of reproduction antique lighting fixtures available for home and outdoor applications, but I have never seen a reproduction antique fluorescent light fixture for the shop or garage.  
And that is what I am trying to create here, a authentic (or close to authentic) reproduction 1941 Westinghouse  fluorescent light fixture.

http://www.lighting-gallery.net/gallery/displayimage.php?album=2949&pos=8&pid=83584

http://www.lighting-gallery.net/gallery/displayimage.php?album=2949&pos=7&pid=83585

 
I am looking at all the problems and difficulties that may be involved first before they eventually happen anyway.

A off the shelf ballast with a separate device to create the preheat starting effect may be the way to go so it  could be replaced separately from the ballast.
If the preheat starting device fails, you could just wire around it and the fixture would still operate.

Exactly...

Like you say may be a electronic ballast could be reprogramed to create the preheat effect without too much wear on the bulbs.
A regular off the shelf electronic ballast could be offered in the fixture as standard and a optional special preheat effect reprogramed electronic ballast could be ordered with the fixture at a extra cost for really hard core users that are into the preheat experience.

It can not be reprogrammed, as the functionality in all of the ballast controllers I know is hard wired mainly analog circuits and very simple digital state machine (just one or maximum two flip-flops - one as the fault latch and the second for the eventual preheat vs operation mode control. But the later is frequently distinguished by just a voltage range across the preheat timing capacitor, so part of the analog)

But with many types you may add small add-on board to just influence the main ballast circuit to get the desired effects.

Personally I always liked the preheat starting effect.
I would say that most people today don't even know what a preheat fluorescent light start even looks like.
It would be a selling point.

Well, in Europe this is not the case, as 99.9% of the magnetic ballasts in wide use are preheat. But I may imagine, in the US, where many decades the RS ruled the market, it will look special...

As for the flicker part, while it would be authentic, it could be a problem.
I remember it well from the 50s and early 60s.
Trying to do anything under a flickering fluorescent lamp was cause for real eye strain.
This was one reason people did not care to use them at home to read a book with.
I would like to stay away from that.

For real illumination task that is indeed not a win, but these things are mostly used just for a "Look what I have" show, where the unstable light will be seen more as a plus...
And that feature could be made controlled by a hidden selector switch: Either operate single (or both, connecting a second ballast as well) lamp at full wave (so no flicker), or two lamps with the authentic flicker, depend on whether some work have to be done, or it is operated just for the show...
 

Probably 99% of the world population could care less about owning a antique fluorescent light fixture.
But if just 1% did, it would be a huge success, 1% of the world population is a lot of people.
Plus for a garage or large shop several would be required.

There are plenty of reproduction antique lighting fixtures available for home and outdoor applications, but I have never seen a reproduction antique florescent light fixture for the shop or garage. 
And that is what I am trying to create here, a authentic (or close to authentic) reproduction 1941 Westinghouse light fixture.

Indeed, I fully agree...
 




[/quote]

Quote from: Larry on February 06, 2014, 04:03:40 PM

A off the shelf ballast with a separate device to create the preheat starting effect may be the way to go so it  could be replaced separately from the ballast.
If the preheat starting device fails, you could just wire around it and the fixture would still operate.

Exactly...

Quote from: Larry on February 06, 2014, 04:03:40 PM

Like you say may be a electronic ballast could be reprogramed to create the preheat effect without too much wear on the bulbs.
A regular off the shelf electronic ballast could be offered in the fixture as standard and a optional special preheat effect reprogramed electronic ballast could be ordered with the fixture at a extra cost for really hard core users that are into the preheat experience.

It can not be reprogrammed, as the functionality in all of the ballast controllers I know is hard wired mainly analog circuits and very simple digital state machine (just one or maximum two flip-flops - one as the fault latch and the second for the eventual preheat vs operation mode control. But the later is frequently distinguished by just a voltage range across the preheat timing capacitor, so part of the analog)

But with many types you may add small add-on board to just influence the main ballast circuit to get the desired effects.

I agree, if a small circuit board could be added to the off the shelf ballast to simulate a preheat start up and could be jumped out in case of a failure, that would be the way to go.
Simple is always better.

I was also thinking that a option could be that the fixture could be ordered without a ballast and the user could install their own magnetic ballast and starter set up if they wanted to.
I don't know if a magnetic preheat ballast is available for the T8 five foot bulb or not, or if one could be adapted.

Here is something else I did not mention before, but the original RF fixture that I have seen in person appeared that the bulbs while 5 foot long were a odd diameter between a T8 and a T12.
I did not measure the bulb diameter so I don't know for sure.
The original bulbs are F85T10.
I would guess T10 is the bulb size.

Is there a T10 size today?
So a T8 is just a little smaller.

So at this time I am going with a five foot T8 as I am not sure how long T12 bulbs are going to be around anyway.
I am not sure when the crazy T12 ban goes into effect here in the states.
I don't like T8 bulbs as they seem too bright and have a glare to them, to me anyway.
But you got use what you can get.

Quote from: Larry on February 06, 2014, 04:03:40 PM

Personally I always liked the preheat starting effect.
I would say that most people today don't even know what a preheat fluorescent light start even looks like.
It would be a selling point.

Well, in Europe this is not the case, as 99.9% of the magnetic ballasts in wide use are preheat. But I may imagine, in the US, where many decades the RS ruled the market, it will look special...

It would be special here as there are few preheat fixtures here anymore unless they are really old.
It is getting harder to find starters and magnetic ballasts, everything is going to electronic ballasts now.
It has to do with the government forcing new lighting standards on everyone no matter how dumb it is.

Quote from: Larry on February 06, 2014, 04:03:40 PM

As for the flicker part, while it would be authentic, it could be a problem.
I remember it well from the 50s and early 60s.
Trying to do anything under a flickering fluorescent lamp was cause for real eye strain.
This was one reason people did not care to use them at home to read a book with.
I would like to stay away from that.

For real illumination task that is indeed not a win, but these things are mostly used just for a "Look what I have" show, where the unstable light will be seen more as a plus...
And that feature could be made controlled by a hidden selector switch: Either operate single (or both, connecting a second ballast as well) lamp at full wave (so no flicker), or two lamps with the authentic flicker, depend on whether some work have to be done, or it is operated just for the show...

Well that is a good idea I did not think of.
As long as there was a switch (Hidden) that could be a demonstration mode and a normal mode, I think it would work.
It would be a great learning tool for electrical engineering students.

I am sure some people will modify these fixtures and be putting T17s or 5 foot power grooves in them for show.
It is bound to happen.

Quote from: Larry on February 06, 2014, 04:03:40 PM

Probably 99% of the world population could care less about owning a antique fluorescent light fixture.
But if just 1% did, it would be a huge success, 1% of the world population is a lot of people.
Plus for a garage or large shop several would be required.

There are plenty of reproduction antique lighting fixtures available for home and outdoor applications, but I have never seen a reproduction antique florescent light fixture for the shop or garage.  
And that is what I am trying to create here, a authentic (or close to authentic) reproduction 1941 Westinghouse light fixture.

Indeed, I fully agree...
 

[/quote]

Here is something and I am sure you have already thought about it.
But if a person is making and selling a light fixture, it is not so simple, here in the states anyway.
Being a electrical device or appliance, there are a bunch of rules and regulations that govern the manufacturing and selling of a light fixture.
 
Is it "green"?
Energy efficiency ratings, and other regulations not to mention UL testing.

But if you just make the fixture with all the parts except the Ballast, bulbs and wire, you just have a metal box.
You could use it for anything from a flower planter to a snow plow for your truck.

If you sold a ballast and wiring in a separate box, you would just be selling some parts
and if you wanted to buy the box and use these parts in your metal box that you bought, no problem.
The wiring is very simple.
You would have to buy the bulbs local anyway.
I am thinking this is the way to go with this.

What am I missing here?
As it sounds too simple.



 

 Hey Everyone,

     I'm new here and think the idea of a reproduction RF fixture is a great idea.

     My $0.02 is that using two F40T8s on independent T8 IS ballasts is the way to go.  These are readily available parts and the only missing piece is a "blinker" box to independently blink the power to the two ballasts to mimic preheat.  Larry, if your blinking strategy doesn't work out I can design a small electronic module to do this.

     While not the best thing for the lamps and ballasts, I don't think blinking a couple times on start-up will be too bad.  My wife has an art studio lit with two 2x32W T8 fixtures.  They originally had cheap, tiny ballasts that only heat one end of the tube.  One died recently so I replaced it with a standard 2 lamp T8 IS ballast.  These lights get cycled at least 4 times a day and they have had the original lamps for at least 4 years.  Based on this, I think the idea of blinking them should still give reasonable lamp life.

      Anyway, just my thoughts, and I hope this works out well for you.  I think between antique car/gas station memorabilia collectors and WWII collectors and museums, this fixture could have a lot of appeal.