I am planning light fittings in my new house and trying to get to
grips with fluorescent lighting. I can visualise how much light a
standard incandescent lamp will give, but find it very hard to do with
fluorescent fittings, particularly the smaller tubes.

Is there a good rule of thumb for comparing the output?

Thanks,
Peter

Peter wrote:
I am planning light fittings in my new house and trying to get to
grips with fluorescent lighting. I can visualise how much light a
standard incandescent lamp will give, but find it very hard to do with
fluorescent fittings, particularly the smaller tubes.

Is there a good rule of thumb for comparing the output?

lumens are the measure of total light output.
Typical incandescant bulbs will produce from about 10-15lm/W.
Typical CF tubes a little under 100lm/W.
Larger linear fluorescents from 100-110lm/W.
So, as a ballpark, around an eighth of the power is needed for
a fluorescent to be as bright as a conventional light.

The wattage equivalent on a lot of CF tubes is somewhat debatable.

In article , Ian Stirling
writes
Peter wrote:
I am planning light fittings in my new house and trying to get to
grips with fluorescent lighting. I can visualise how much light a
standard incandescent lamp will give, but find it very hard to do with
fluorescent fittings, particularly the smaller tubes.

Is there a good rule of thumb for comparing the output?

lumens are the measure of total light output.
Typical incandescant bulbs will produce from about 10-15lm/W.
Typical CF tubes a little under 100lm/W.
Larger linear fluorescents from 100-110lm/W.
So, as a ballpark, around an eighth of the power is needed for
a fluorescent to be as bright as a conventional light.

The wattage equivalent on a lot of CF tubes is somewhat debatable.

Course there are those who might say that fluorescent lighting has no
place in the home....
--
Tony Sayer

On Sat, 20 Mar 2004 12:16:24 GMT, Ian Stirling
wrote:

Peter wrote:
I am planning light fittings in my new house and trying to get to
grips with fluorescent lighting. I can visualise how much light a
standard incandescent lamp will give, but find it very hard to do with
fluorescent fittings, particularly the smaller tubes.

Is there a good rule of thumb for comparing the output?

lumens are the measure of total light output.
Typical incandescant bulbs will produce from about 10-15lm/W.
Typical CF tubes a little under 100lm/W.
Larger linear fluorescents from 100-110lm/W.
So, as a ballpark, around an eighth of the power is needed for
a fluorescent to be as bright as a conventional light.

The wattage equivalent on a lot of CF tubes is somewhat debatable.


But why would you want them? They're horrible (unless you don't mind
looking bilious of course.....


..andy

To email, substitute .nospam with .gl

"Peter" wrote in message
...

I am planning light fittings in my new house and trying to get to
grips with fluorescent lighting. I can visualise how much light a
standard incandescent lamp will give, but find it very hard to do with
fluorescent fittings, particularly the smaller tubes.

Is there a good rule of thumb for comparing the output?

http://www.tlc-direct.co.uk/Technica...umen_Other.htm
says 730 lumens from a 60W incandescent

http://www.tlc-direct.co.uk/Technica...en_Compact.htm
says about 900 lumens from a 15W compact
(but the cheap ones are about 750 lumens)

http://www.tlc-direct.co.uk/Technica...en_Compact.htm
says 880 lumens from a 13W tube (21 inches)

In message
Andy Hall wrote:

On Sat, 20 Mar 2004 12:16:24 GMT, Ian Stirling
wrote:

Peter wrote:
I am planning light fittings in my new house and trying to get to
grips with fluorescent lighting. I can visualise how much light a
standard incandescent lamp will give, but find it very hard to do with
fluorescent fittings, particularly the smaller tubes.

Is there a good rule of thumb for comparing the output?

lumens are the measure of total light output.
Typical incandescant bulbs will produce from about 10-15lm/W.
Typical CF tubes a little under 100lm/W.
Larger linear fluorescents from 100-110lm/W.
So, as a ballpark, around an eighth of the power is needed for
a fluorescent to be as bright as a conventional light.

The wattage equivalent on a lot of CF tubes is somewhat debatable.


But why would you want them? They're horrible (unless you don't mind
looking bilious of course.....
Not if you use a good diffuser. but this cuts down on the light. So I use
a 4 to 1 for the power output
--
J.P. Kerslake B.Sc., F.B.I.S. Dyslexia Rules KO.
Pager 07626 - 235878, "phone" 01248 - 353264
e-mail Home = ,
remove NOSPAM before using

tony sayer wrote in message ...

Course there are those who might say that fluorescent lighting has no
place in the home....

some do, but this is based on widspread poor practice with them. With
good practices they make excellant home lighting.

Regards, NT

In article ,
tony sayer wrote:
Course there are those who might say that fluorescent lighting has no
place in the home....

As a naked white tube in the middle of a ceiling, I'd agree. But there are
many different colour temperature tubes available from specialists, and
very pleasant effects can be had from reflected light.

--
*Never underestimate the power of stupid people in large groups.

Dave Plowman London SW 12
RIP Acorn

On 20 Mar 2004 11:46:25 -0800, (N. Thornton) wrote:

tony sayer wrote in message ...

Course there are those who might say that fluorescent lighting has no
place in the home....

some do, but this is based on widspread poor practice with them. With
good practices they make excellant home lighting.

Regards, NT


Except that they are still cold and bilious looking and far from
welcoming.

This is OK for a workshop or perhaps at a pinch a study when working,
but not for reception rooms, bedrooms etc.

Perhaps with mixing with some sort of proper tungsten lighting, there
are occasions where certain types of fluoresecent are just about OK,
but certainly not in isolation in a domestic setting.





..andy

To email, substitute .nospam with .gl

Dave Plowman wrote:
In article ,
tony sayer wrote:
Course there are those who might say that fluorescent lighting has no
place in the home....

As a naked white tube in the middle of a ceiling, I'd agree. But there are
many different colour temperature tubes available from specialists, and
very pleasant effects can be had from reflected light.

Especially for the not-so-well-off.
A well lit room, with appropriate shades can be much nicer than one
where there is one 60W bulb to save on electricity.
It's not hard in many homes to save 40-50 quid a year on electricity
this way.
Which is not a trivial amount for everyone.

In article ,
Andy Hall wrote:
Except that they are still cold and bilious looking and far from
welcoming.

Well, then daylight will be the same, as it's easier to produce a soft
artificial light source to simulate this with florries than incandescents.

This is OK for a workshop or perhaps at a pinch a study when working,
but not for reception rooms, bedrooms etc.

Think you've missed out kitchens - perhaps the most important workshop in
the average house.

Perhaps with mixing with some sort of proper tungsten lighting, there
are occasions where certain types of fluoresecent are just about OK,
but certainly not in isolation in a domestic setting.

If you conceal them by any one of a number of methods, and use decent
tubes, they're great - especially to give a choice of moods in a room.
They also have the benefit of cool running, high efficiency and long life
with electronic ballasts.

--
*If you try to fail and succeed, which have you done? *

Dave Plowman London SW 12
RIP Acorn

On Sat, 20 Mar 2004 23:58:56 +0000 (GMT), Dave Plowman
wrote:

In article ,
Andy Hall wrote:
Except that they are still cold and bilious looking and far from
welcoming.

Well, then daylight will be the same, as it's easier to produce a soft
artificial light source to simulate this with florries than incandescents.

Not really. Different application. I don't want simulated daylight
during the hours of darkness apart from in work rooms and in work
areas.


This is OK for a workshop or perhaps at a pinch a study when working,
but not for reception rooms, bedrooms etc.

Think you've missed out kitchens - perhaps the most important workshop in
the average house.

No, I use small daylight type fluorescents only over worktop areas
while it's necessary and then revert to proper tungsten and halogen
lights apart from that. I'm not setting out to produce a commercial
kitchen and prefer softer lighting except when and where absolutely
necessary.


Perhaps with mixing with some sort of proper tungsten lighting, there
are occasions where certain types of fluoresecent are just about OK,
but certainly not in isolation in a domestic setting.

If you conceal them by any one of a number of methods, and use decent
tubes, they're great - especially to give a choice of moods in a room.

I'm aware that there are different tube types and have tried many and
in different settings, but never found any that I like other than for
workshop applications.

They also have the benefit of cool running, high efficiency and long life
with electronic ballasts.

Where I do use them I only use electronic ballasts. They are even
worse when run at mains frequency. I am sensitive to flicker from
phosphor devices like tubes and CRTs so find electronic ballasts
essential anyway


..andy

To email, substitute .nospam with .gl

In article ,
Ian Stirling writes:
Peter wrote:
I am planning light fittings in my new house and trying to get to
grips with fluorescent lighting. I can visualise how much light a
standard incandescent lamp will give, but find it very hard to do with
fluorescent fittings, particularly the smaller tubes.

Is there a good rule of thumb for comparing the output?

lumens are the measure of total light output.
Typical incandescant bulbs will produce from about 10-15lm/W.
Typical CF tubes a little under 100lm/W.
Larger linear fluorescents from 100-110lm/W.

These are ignoring control gear and other losses.
You need to halve them in practice (unless you hang a
bare fluorescent 12" below the ceiling with no fitting;-).

So, as a ballpark, around an eighth of the power is needed for
a fluorescent to be as bright as a conventional light.

4:1 is the normal figure used for compact fluorescent retrofits.

The wattage equivalent on a lot of CF tubes is somewhat debatable.

The catch is they are compared with light output from 'soft'
coloured filament lamps, not what you normally use (and CF
retrofits are nearly all 2700K to match regular filament lamp
colour anyway).

--
Andrew Gabriel

On Sat, 20 Mar 2004 14:57:21 -0000, "Nick Finnigan"
wrote:

"Peter" wrote in message
.. .

I am planning light fittings in my new house and trying to get to
grips with fluorescent lighting. I can visualise how much light a
standard incandescent lamp will give, but find it very hard to do with
fluorescent fittings, particularly the smaller tubes.

Is there a good rule of thumb for comparing the output?

http://www.tlc-direct.co.uk/Technica...umen_Other.htm
says 730 lumens from a 60W incandescent

http://www.tlc-direct.co.uk/Technica...en_Compact.htm
says about 900 lumens from a 15W compact
(but the cheap ones are about 750 lumens)

http://www.tlc-direct.co.uk/Technica...en_Compact.htm
says 880 lumens from a 13W tube (21 inches)


Thanks all for the helpful replies. Most of my lights are going to be
incandescents, apart from the kitchen where it will have a mix. The
area that I think I will fit small fluorescents to are in the walk-in
cupboards, noting the need for care with the choice of tube.

Peter

In article ,
Andy Hall wrote:
Where I do use them I only use electronic ballasts. They are even
worse when run at mains frequency. I am sensitive to flicker from
phosphor devices like tubes and CRTs so find electronic ballasts
essential anyway

Again, flicker will be increased by the poor choice of tubes. And, of
course, I meant high frequency ballasts. No point in only half doing the
job.

--
*I love cats...they taste just like chicken.

Dave Plowman London SW 12
RIP Acorn

In article ,
Peter wrote:
The area that I think I will fit small fluorescents to are in the
walk-in cupboards, noting the need for care with the choice of tube.

I doubt it's worth paying the considerable extra for 'special' tubes for
occasional short use.

--
*Why do we say something is out of whack? What is a whack? *

Dave Plowman London SW 12
RIP Acorn

On Sun, 21 Mar 2004 09:36:15 +0000 (GMT), Dave Plowman
wrote:

In article ,
Andy Hall wrote:
Where I do use them I only use electronic ballasts. They are even
worse when run at mains frequency. I am sensitive to flicker from
phosphor devices like tubes and CRTs so find electronic ballasts
essential anyway

Again, flicker will be increased by the poor choice of tubes. And, of
course, I meant high frequency ballasts. No point in only half doing the
job.

Yes, sure. That's what I meant as well. I'm not sure that there
are electronic ballasts that are not HF though??


..andy

To email, substitute .nospam with .gl

In article ,
Andy Hall wrote:
Again, flicker will be increased by the poor choice of tubes. And, of
course, I meant high frequency ballasts. No point in only half doing the
job.

Yes, sure. That's what I meant as well. I'm not sure that there
are electronic ballasts that are not HF though??

Think there might have been, early on. But I mis-read your original. ;-)

I'm not saying that florries have a place in every room - merely that they
shouldn't be ruled out on the basis of the experience of only a basic
white strip light in the middle of the ceiling. But to me, carefully used,
they are more suited to domestic lighting than those mainly horrid CFLs,
which I reserve for outdoors.

--
*Women like silent men; they think they're listening.

Dave Plowman London SW 12
RIP Acorn

On Sun, 21 Mar 2004 12:07:00 +0000 (GMT), Dave Plowman
wrote:

In article ,
Andy Hall wrote:
Again, flicker will be increased by the poor choice of tubes. And, of
course, I meant high frequency ballasts. No point in only half doing the
job.

Yes, sure. That's what I meant as well. I'm not sure that there
are electronic ballasts that are not HF though??

Think there might have been, early on. But I mis-read your original. ;-)

I'm not saying that florries have a place in every room - merely that they
shouldn't be ruled out on the basis of the experience of only a basic
white strip light in the middle of the ceiling. But to me, carefully used,
they are more suited to domestic lighting than those mainly horrid CFLs,
which I reserve for outdoors.

Agreed


..andy

To email, substitute .nospam with .gl

Andy Hall wrote in message . ..
On 20 Mar 2004 11:46:25 -0800, (N. Thornton) wrote:
tony sayer wrote in message ...

Course there are those who might say that fluorescent lighting has no
place in the home....

some do, but this is based on widspread poor practice with them. With
good practices they make excellant home lighting.

Except that they are still cold and bilious looking and far from
welcoming.

Depends how theyre installed, which type of tube is used, and what
light level is chosen. People tend to use far too much power, use the
wrong tubes, and use installation types that are bad looking and
provide bad lighting.

At the last place the lighting was excellant, soft warm and pleasant.
It was 3500K fluorescent. The night lighting was 2-3w cool white,
which created a moonlit effect.

There are many things that can go wrong, and unfortunately often do,
due I think to shortage of knowledge of how to make these lights work
well.


Regards, NT

Andy Hall wrote in message . ..
On Sat, 20 Mar 2004 23:58:56 +0000 (GMT), Dave Plowman
Andy Hall wrote:


This is OK for a workshop or perhaps at a pinch a study when working,
but not for reception rooms, bedrooms etc.

Think you've missed out kitchens - perhaps the most important workshop in
the average house.

No, I use small daylight type fluorescents only over worktop areas
while it's necessary and then revert to proper tungsten and halogen
lights apart from that. I'm not setting out to produce a commercial
kitchen and prefer softer lighting except when and where absolutely
necessary.

Daylights are not one of the better ones, theyre quite an old fl
technology.


Perhaps with mixing with some sort of proper tungsten lighting, there
are occasions where certain types of fluoresecent are just about OK,
but certainly not in isolation in a domestic setting.

If you conceal them by any one of a number of methods, and use decent
tubes, they're great - especially to give a choice of moods in a room.

I'm aware that there are different tube types and have tried many and
in different settings, but never found any that I like other than for
workshop applications.

Which ones have you tried? I like 3500k for general house use, and
some of the Philips numbered ones are good when a less warm light is
wanted, such as for daylight boosting, or working use. Look for high
CRI and low light temperature. There are also full spectrum tubes.


They also have the benefit of cool running, high efficiency and long life
with electronic ballasts.

Where I do use them I only use electronic ballasts. They are even
worse when run at mains frequency. I am sensitive to flicker from
phosphor devices like tubes and CRTs so find electronic ballasts
essential anyway

Fls running off high frequency ballasts supplied by dc are competely
flicker free. Not all electronic ballasts are flicker free. Filament
bulbs OTOH are not flicker free.


Regards, NT

Andy Hall wrote in message . ..
On Sat, 20 Mar 2004 23:58:56 +0000 (GMT), Dave Plowman
Andy Hall wrote:


This is OK for a workshop or perhaps at a pinch a study when working,
but not for reception rooms, bedrooms etc.

Think you've missed out kitchens - perhaps the most important workshop in
the average house.

No, I use small daylight type fluorescents only over worktop areas
while it's necessary and then revert to proper tungsten and halogen
lights apart from that. I'm not setting out to produce a commercial
kitchen and prefer softer lighting except when and where absolutely
necessary.

Daylights are not one of the better ones, theyre quite an old fl
technology.


Perhaps with mixing with some sort of proper tungsten lighting, there
are occasions where certain types of fluoresecent are just about OK,
but certainly not in isolation in a domestic setting.

If you conceal them by any one of a number of methods, and use decent
tubes, they're great - especially to give a choice of moods in a room.

I'm aware that there are different tube types and have tried many and
in different settings, but never found any that I like other than for
workshop applications.

Which ones have you tried? I like 3500k for general house use, and
some of the Philips numbered ones are good when a less warm light is
wanted, such as for daylight boosting, or working use. Look for high
CRI and low light temperature. There are also full spectrum tubes.


They also have the benefit of cool running, high efficiency and long life
with electronic ballasts.

Where I do use them I only use electronic ballasts. They are even
worse when run at mains frequency. I am sensitive to flicker from
phosphor devices like tubes and CRTs so find electronic ballasts
essential anyway

Fls running off high frequency ballasts supplied by dc are competely
flicker free. Not all electronic ballasts are flicker free. Filament
bulbs OTOH are not flicker free.


Regards, NT

On 21 Mar 2004 06:10:08 -0800, (N. Thornton) wrote:



Daylights are not one of the better ones, theyre quite an old fl
technology.

I've used a combination of these and triphosphor types for workshop
use and get the results that I want.


Perhaps with mixing with some sort of proper tungsten lighting, there
are occasions where certain types of fluoresecent are just about OK,
but certainly not in isolation in a domestic setting.

If you conceal them by any one of a number of methods, and use decent
tubes, they're great - especially to give a choice of moods in a room.

I'm aware that there are different tube types and have tried many and
in different settings, but never found any that I like other than for
workshop applications.

Which ones have you tried? I like 3500k for general house use, and
some of the Philips numbered ones are good when a less warm light is
wanted, such as for daylight boosting, or working use. Look for high
CRI and low light temperature. There are also full spectrum tubes.

In places where tungsten lighting is appropriate, I have fittings that
use them. All of the CFL types, apart from looking artificial, ar
plug ugly as well.




Fls running off high frequency ballasts supplied by dc are competely
flicker free. Not all electronic ballasts are flicker free. Filament
bulbs OTOH are not flicker free.

They are adequately low flicker in comparison with simple choke
fluoresecents. I don't have any of the latter, but entirely HF
electronic types in the small number of locations where they are
appropriate.



..andy

To email, substitute .nospam with .gl

In article ,
(N. Thornton) writes:
Andy Hall wrote in message . ..
Where I do use them I only use electronic ballasts. They are even
worse when run at mains frequency. I am sensitive to flicker from
phosphor devices like tubes and CRTs so find electronic ballasts
essential anyway

Fls running off high frequency ballasts supplied by dc are competely
flicker free. Not all electronic ballasts are flicker free. Filament
bulbs OTOH are not flicker free.

Flicker at twice the line frequency, 100Hz, is not perceptable by
any person. About half the poputation can see 60Hz, and no one can
see above 76Hz. You need to go to things with smaller faster brains
than humans before you can see 100Hz -- insects can.

The main flicker from traditional fluorescent lamps is at twice the
line frequency. It's very bad, most lamps go almost out 100 times a
second. Another issue is that the phosphors making up the various
colour components have different persistance, so the lamp colour
changes 100 times a second[*]. Fortunately you can't see any of this
because it's way above the speed of the fastest human brain (unless
you have an exceptionally small brain but then you've probably got
far more serious things to worry about anyway;-)

The problem from traditional fluorescent lamps is if they don't
give out the same light level when conducting in each direction.
When that happens, you now have a lamp which is changing intensity
50 times a second, and well over half the population can see that.
This could happen with a badly/cheaply made tube where the electrodes
are not well matched. It also happens for a few hours just before a
tube fails completely (assuming regular switch-start control gear --
some other control gear can keep a tube running indefinately in this
state).

The tube ends can also flicker at 50Hz due to the different mechanisms
employed when the electrode switches from an anode to a cathode 50
times a second. Masking the tube ends is a way which has been used
to overcome this prior to electronic control gear.

You are right that electronic ballasts are not flicker free. They
often flicker at twice the line frequency, but as that's way above
what a human can see, it is of no consequence. The issue of unequal
light levels when the tube conducts in each direction is not relevant
now because the electronic control gear reverses the current flow
typically 20,000 times/second, and in any case, above around 5,000
times/second, a different mechanism operates in the discharge and
it becomes continuous anyway, even if the current flow isn't.
[*] Here's an interesting practical to try at home (or maybe out in
the garden;-) Arrange for a mains fluorescent tube to be operating
on the end of around 6' of flex, remote from its control gear.
One of the small 4/6/8W lamps would be ideal, particularly one
of the inspection lamp types where it's suitably encased.
Attach the tube very securely to the flex. Having ensured adiquate
clearence, go outside at night, switch the tube on, and now swirl
it round and round on the flex. You should now see the 100Hz
stroboscopic flashing, and you will also see how the lamp colour
changes 100 times/second, due to the different persistance of the
various phosphors. Obviously, you need to take various safety
precautions, such as an RCD and safety goggles particularly if
you're going to take a class of children outside to observe, and
you might end up having to clear up a broken fluorescent tube....

--
Andrew Gabriel

Andrew Gabriel wrote:
In article ,
Ian Stirling writes:
Peter wrote:
I am planning light fittings in my new house and trying to get to
grips with fluorescent lighting. I can visualise how much light a
standard incandescent lamp will give, but find it very hard to do with
fluorescent fittings, particularly the smaller tubes.

Is there a good rule of thumb for comparing the output?

lumens are the measure of total light output.
Typical incandescant bulbs will produce from about 10-15lm/W.
Typical CF tubes a little under 100lm/W.
Larger linear fluorescents from 100-110lm/W.

These are ignoring control gear and other losses.

Modern control gear is usually over 90% efficiant, apart from
the low end CF tubes.

You need to halve them in practice (unless you hang a
bare fluorescent 12" below the ceiling with no fitting;-).

Why should this be so, when it's not true with conventional lights
(if done as a direct replacement)?


So, as a ballpark, around an eighth of the power is needed for
a fluorescent to be as bright as a conventional light.

4:1 is the normal figure used for compact fluorescent retrofits.

(Andrew Gabriel) wrote in message ...


Good account there. I'd just add 2 things: electronic ballasts dont
always ensure perfectly symmetrical current flow in the 2 half cycles,
hence the line frequency element of flicker can still occur with some
types.

The other thing is you can see the colour bands and the on-off effect
just by darting your eyes left to right with a still light. I'm sure
you trick is more visual though

Regards, NT

N. Thornton wrote:
(Andrew Gabriel) wrote in message ...


Good account there. I'd just add 2 things: electronic ballasts dont
always ensure perfectly symmetrical current flow in the 2 half cycles,
hence the line frequency element of flicker can still occur with some
types.

All the electronic balasts I've taken apart (probably 5-8 different models)
have a bridge rectifier/capacitor before everything else.
The only asymmetry could arise from differential heating of the diodes,
or manufacturing differences.
This is going to be at the very outside 30-50mv.
On a line going to +-340V, this is effectively zero.

Ian Stirling wrote in message ...
N. Thornton wrote:
(Andrew Gabriel) wrote in message ...

Good account there. I'd just add 2 things: electronic ballasts dont
always ensure perfectly symmetrical current flow in the 2 half cycles,
hence the line frequency element of flicker can still occur with some
types.

All the electronic balasts I've taken apart (probably 5-8 different models)
have a bridge rectifier/capacitor before everything else.
The only asymmetry could arise from differential heating of the diodes,
or manufacturing differences.
This is going to be at the very outside 30-50mv.
On a line going to +-340V, this is effectively zero.

A bridge rec isnt going to prevent asymmety though. A series cap will,
a reservoir cap wont. The first electronic fitting I had flickered
severely during start up, at 50Hz.

Regards, NT

N. Thornton wrote:
Ian Stirling wrote in message ...
N. Thornton wrote:
(Andrew Gabriel) wrote in message ...

Good account there. I'd just add 2 things: electronic ballasts dont
always ensure perfectly symmetrical current flow in the 2 half cycles,
hence the line frequency element of flicker can still occur with some
types.

All the electronic balasts I've taken apart (probably 5-8 different models)
have a bridge rectifier/capacitor before everything else.
The only asymmetry could arise from differential heating of the diodes,
or manufacturing differences.
This is going to be at the very outside 30-50mv.
On a line going to +-340V, this is effectively zero.

A bridge rec isnt going to prevent asymmety though. A series cap will,
a reservoir cap wont. The first electronic fitting I had flickered
severely during start up, at 50Hz.

Combined with the fact that AC mains has very little DC component it will.
If there is a bridge rectifier, then there is no 50Hz component
in the output of it, only 100Hz.

In article ,
(N. Thornton) writes:
Ian Stirling wrote in message ...
N. Thornton wrote:
(Andrew Gabriel) wrote in message ...

Good account there. I'd just add 2 things: electronic ballasts dont
always ensure perfectly symmetrical current flow in the 2 half cycles,
hence the line frequency element of flicker can still occur with some
types.

All the electronic balasts I've taken apart (probably 5-8 different models)
have a bridge rectifier/capacitor before everything else.
The only asymmetry could arise from differential heating of the diodes,
or manufacturing differences.
This is going to be at the very outside 30-50mv.
On a line going to +-340V, this is effectively zero.

A bridge rec isnt going to prevent asymmety though. A series cap will,
a reservoir cap wont. The first electronic fitting I had flickered
severely during start up, at 50Hz.

Please explain where you think there's any 50Hz signal in an
electronic control gear circuit.

--
Andrew Gabriel

Ian Stirling wrote in message .. .
N. Thornton wrote:
(Andrew Gabriel) wrote in message ...

Good account there. I'd just add 2 things: electronic ballasts dont
always ensure perfectly symmetrical current flow in the 2 half cycles,
hence the line frequency element of flicker can still occur with some
types.

All the electronic balasts I've taken apart (probably 5-8 different models)
have a bridge rectifier/capacitor before everything else.
The only asymmetry could arise from differential heating of the diodes,
or manufacturing differences.
This is going to be at the very outside 30-50mv.
On a line going to +-340V, this is effectively zero.

A bridge rec isnt going to prevent asymmety though. A series cap will,
a reservoir cap wont. The first electronic fitting I had flickered
severely during start up, at 50Hz.

Combined with the fact that AC mains has very little DC component it will.
If there is a bridge rectifier, then there is no 50Hz component
in the output of it, only 100Hz.

and Andrew Gabriel wrote:

Please explain where you think there's any 50Hz signal in an
electronic control gear circuit.


OK, the factors stated above do not ensure no 50Hz current is present.
If the load were resistive, capacitive or inductive they would, but a
fl tube is none of those. A fl tube has 2 separate emitters, each one
controlling one half of the current cycle. Now if the emission of
those is uneven, when the tube is put in series with an electronic
ballast with a BR input, the resulting tube current will be
asymmetrical. The tube emitters are 2 of the current controlling
factors.

If the ballast has a series capacitor at its input, before any BR,
then symmetry will be ensured, but this is not always present.

I'm sure a diagram would clarify, but I'm equally sure it would take
ages

With such a setup, if one emitter has total failure, the tube can
conduct current one way only, giving intolerably strong 50Hz flicker.


Regards, NT

N. Thornton wrote:
Ian Stirling wrote in message .. .
N. Thornton wrote:
(Andrew Gabriel) wrote in message ...

Good account there. I'd just add 2 things: electronic ballasts dont
always ensure perfectly symmetrical current flow in the 2 half cycles,
hence the line frequency element of flicker can still occur with some
types.

All the electronic balasts I've taken apart (probably 5-8 different models)
have a bridge rectifier/capacitor before everything else.
The only asymmetry could arise from differential heating of the diodes,
or manufacturing differences.
This is going to be at the very outside 30-50mv.
On a line going to +-340V, this is effectively zero.

A bridge rec isnt going to prevent asymmety though. A series cap will,
a reservoir cap wont. The first electronic fitting I had flickered
severely during start up, at 50Hz.

Combined with the fact that AC mains has very little DC component it will.
If there is a bridge rectifier, then there is no 50Hz component
in the output of it, only 100Hz.

and Andrew Gabriel wrote:

Please explain where you think there's any 50Hz signal in an
electronic control gear circuit.


OK, the factors stated above do not ensure no 50Hz current is present.
snip
With such a setup, if one emitter has total failure, the tube can
conduct current one way only, giving intolerably strong 50Hz flicker.

No, it can't.

An electronic ballast has a rectifier at the front of it.
The waveform after the rectifier is NOT a 50Hz sine wave.

Ian Stirling wrote in message ...
NT wrote...

OK, the factors stated above do not ensure no 50Hz current is present.
snip
With such a setup, if one emitter has total failure, the tube can
conduct current one way only, giving intolerably strong 50Hz flicker.

No, it can't.

An electronic ballast has a rectifier at the front of it.
The waveform after the rectifier is NOT a 50Hz sine wave.

I'd have to draw the cct and label the waveforms, and I'm too busy
today. I could sit here and assure you it can flicker at 50Hz, but
that wont convince either of us. Maybe if I get the time later I'll
draw it and we'll see what comes up.


Regards, NT

N. Thornton wrote:
Ian Stirling wrote in message ...
NT wrote...

OK, the factors stated above do not ensure no 50Hz current is present.
snip
With such a setup, if one emitter has total failure, the tube can
conduct current one way only, giving intolerably strong 50Hz flicker.

No, it can't.

An electronic ballast has a rectifier at the front of it.
The waveform after the rectifier is NOT a 50Hz sine wave.

I'd have to draw the cct and label the waveforms, and I'm too busy
today. I could sit here and assure you it can flicker at 50Hz, but
that wont convince either of us. Maybe if I get the time later I'll
draw it and we'll see what comes up.

I'm not saying it's impossible.
However, after the bridge rectifier and capacitor, the waveform
looks like (view in fixed font)



340V .. ..
. ~-_ .
240V . -~-_ .
~~




0V ----10ms---


The difference in successive crests varies by millivolts at most.
The slope of the decay, and the voltage it gets down to depends on the
load and the size of the capacitor, which varies.

What can happen with a marginal bulb or broken driver is that it may
try to restrike the tube often, and it doesn't quite work, leading to
pronounced flicker.

Ian Stirling wrote in message .. .
N. Thornton wrote:

OK, the factors stated above do not ensure no 50Hz current is present.
snip
With such a setup, if one emitter has total failure, the tube can
conduct current one way only, giving intolerably strong 50Hz flicker.

No, it can't.

An electronic ballast has a rectifier at the front of it.
The waveform after the rectifier is NOT a 50Hz sine wave.

I'd have to draw the cct and label the waveforms, and I'm too busy
today. I could sit here and assure you it can flicker at 50Hz, but
that wont convince either of us. Maybe if I get the time later I'll
draw it and we'll see what comes up.

I'm not saying it's impossible.
snip
What can happen with a marginal bulb or broken driver is that it may
try to restrike the tube often, and it doesn't quite work, leading to
pronounced flicker.


I think I understand where our wires are crossing. There are 2 ways to
wire an electronic ballast.

One way is to rectify the mains, smooth it, generate hf ac, and apply
that to the fl tube. That method wont produce 50Hz flicker.


The other way is to put the ballast in series with the tube, like
this:

~L--------ballast---------tube---------+
|
~N-------------------------------------+

In this case 50Hz mains is going through the tube, not hf ac. The
ballast contains the usual rectifier and circuitry, but the tube is on
the ac side, not the dc side of this rectifier. Now if one tube
electrode loses emission, the light will function but at 50Hz instead
of 100Hz. It will light every other half cycle.

In this type of setup there is nothing to prevent 50Hz flicker. It
should not happen as long as the tube is capable of supplying
sufficient current each way, since the ballast limits the i flow
equally. But when one emitter is performing poorly, 50Hz flicker can
become strong. And when one emitter breaks the 50Hz flicker is
intense.

These ballasts work by turning the rectified ac into hf ac, passing
that through a choke. The 'output' of the choke is simply shorted, the
real load being the tube in series with the whole of the ballast
circuit.


Regards, NT

In article ,
(N. Thornton) writes:

I think I understand where our wires are crossing. There are 2 ways to
wire an electronic ballast.

One way is to rectify the mains, smooth it, generate hf ac, and apply
that to the fl tube. That method wont produce 50Hz flicker.


The other way is to put the ballast in series with the tube, like
this:

~L--------ballast---------tube---------+
|
~N-------------------------------------+

Never seen or heard of electronic ballast like this.
Since it loses the advantages of both electronic and traditional
ballasts, and combines their disadvantages, it would be completely
pointless and isn't used.

--
Andrew Gabriel

(Andrew Gabriel) wrote in message ...

Since it loses the advantages of both electronic and traditional
ballasts, and combines their disadvantages,

I dont see how that would be so. Care to tell us what the pros and cons you see are?


Regards, NT

In article ,
(N. Thornton) writes:
(Andrew Gabriel) wrote in message ...

Since it loses the advantages of both electronic and traditional
ballasts, and combines their disadvantages,

I dont see how that would be so. Care to tell us what the pros and cons you see are?

Traditional ballasts:
Very reliable and long life component (except in the US;-).
Electronic control gear:
Life follows standard reliability curve for medium current
semiconductor circuits (some early failures, a few years
without problems, then gradual increasing failure rate).

Traditional ballasts:
Can generate 50Hz flicker with cheaper tubes.
Can continue trying to start a dead lamp.
Electronic control gear:
10% higher light output by running tube at ~5kHz (20kHz is typical).
No flicker.
Dead lamps remain extinguished.


If I'm understanding your scheme correctly, it provides only all
the disadvantageous points, so it's worse than either a traditional
ballast or electronic control gear, each of which does have some
advantages. It's not going to be any cheaper to make than either of
these either.

--
Andrew Gabriel

(Andrew Gabriel) wrote in message ...
(N. Thornton) writes:
(Andrew Gabriel) wrote in message news:


Traditional ballasts:
Very reliable and long life component (except in the US;-).
Electronic control gear:
Life follows standard reliability curve for medium current
semiconductor circuits (some early failures, a few years
without problems, then gradual increasing failure rate).

Traditional ballasts:
Can generate 50Hz flicker with cheaper tubes.
Can continue trying to start a dead lamp.
Electronic control gear:
10% higher light output by running tube at ~5kHz (20kHz is typical).
No flicker.
Dead lamps remain extinguished.
Also more energy efficient,
small and light


If I'm understanding your scheme correctly, it provides only all
the disadvantageous points, so it's worse than either a traditional
ballast or electronic control gear, each of which does have some
advantages. It's not going to be any cheaper to make than either of
these either.

I've tried to remember with more clarity, and I cant. The first tronic
fl fitting I had I made the thingy for, and it slotted in without
rewiring. So it must have been the type where the tube stayed on the
ac side. The second fitting I didnt make, but again flicker was an
issue on occasion. But I agree the tube straight on the OPTF has 2
advantages.

FWLIW there are also 50Hz choke fittings that dont keep trying to
start a duff tube, but I'll let someone else tell us what kind they
are


Regards, NT

In article ,
(N. Thornton) writes:

FWLIW there are also 50Hz choke fittings that dont keep trying to
start a duff tube, but I'll let someone else tell us what kind they
are

The most effective of the 50Hz circuits in this respect is
actually conventional switch-start, but with an electronic
starter substituting the glow starter.

There are lots of other types of 50Hz control gear. There is
a significant problem in trying to name them, as the same
names are used for significantly different control gear
circuits in the UK and US.

The one we're most familar with here which has a separate
starter is called switch-start. In the US, it's called
pre-heat, but doesn't work on 120V supplies with tubes longer
than about 2'. In US, the term switch-start is used for a
similar circuit but with a manually operated starting switch,
which is pretty unheard of in the UK. In the UK, pre-heat is
a generic term which means any type of control gear which
tries to preheat the tube filaments before starting the main
discharge, which includes switch-start and lots of other
types.

Then there are a number of variations which come under names
like rapid-start, quick-start, where the tube filaments are
powered by a separate transformer and there is no starter,
but are otherwise similar to switch-start in that a series
inductor limits the main tube current. The variations are
in where the primary of the filament transformer is connected;
sometimes it's across the mains, sometimes it's across the tube.
The US versions of these also include a step-up transformer as
120V isn't enough for tubes longer than around 2'. These are
common in the US, but not so common in the UK as they are
more expensive to make than our switch-start, and not as
reliable.

The UK had a scheme known as semi-resonant start. This used
a double wound transformer and an essential circuit capacitor.
When power is first applied and no discharge is established,
the transformer and capacitor 'ring' at 50Hz generating about
twice mains voltage across the tube and a current through the
filaments. As the filaments heat up and the discharge starts,
that changes the nature of the circuit, and the transformer
and capacitor simply form a current limiting ballast. This
was a realy nice design from many points of view as the power
factor is almost 1 when running, the twice mains voltage means
it can start long lamps at very low temperatures, the way the
lamps come on is just like you turn up a dimmer from nothing
to full over ~5 seconds, and lamp life was very long (normally
much longer than manufacturer's standard ratings). The
disadvantages are that it won't work with tubes less than 5'
long as the twice mains voltage could cause them to strike
cold, and ~5 seconds to come on is a little too long for some
purposes (this is because the filament current is lower than
in other control gear circuits).

The US also has instant-start, where the tube is started by
a high voltage and no attempt is made to use the filaments
at all. Tube life isn't good if frequently switched. They
make tubes specially for instant start which only have one
pin at each end, although the tube still contains a filament,
but with both ends wired to the one pin. (During tube
manufacture, it is necessary to heat the filaments, so the
two wires have to be brough out of the glass envelope
separately.) Some instant-start fittings use these and others
use bi-pin tubes and just connect the two filament ends in
the lampholder. In the UK, instant-start is a generic term
for all types of control gear which try to establish the
discharge without first heating the filaments, i.e. the
opposite of pre-heat.

Then there are all the electronic variations, but that's
enough for now!

--
Andrew Gabriel