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Old March 1st 19, 04:02 PM posted to uk.d-i-y
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"whisky-dave" wrote in message
...

Dimmable fluorescent fittings have been around since the early 1960s.
Nothing new there.


How are fluorescents dimmed? I'd always thought that it was impossible, and
was surprised when the fluorescents in my school lecture theatre could be
dimmed. They were probably installed in the early to mid 70s, which gives an
idea of what technology was available then. I remember a huge cabinet about
the size of a 6-foot high freezer in the projection unit which gave off a
hell of a hum as the lights were going from full off to full on, which they
did on a timer: the lecturer pressed a button and they dimmed/brightened
automatically over the course of about 5 seconds.


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Old March 1st 19, 04:30 PM posted to uk.d-i-y
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On Friday, 1 March 2019 16:02:52 UTC, NY wrote:
"whisky-dave" wrote in message
...

Dimmable fluorescent fittings have been around since the early 1960s.
Nothing new there.


How are fluorescents dimmed?


I waqsnt; sure so looked it up.

https://www.etcconnect.com/Support/A...ures-Work.aspx

I'd always thought that it was impossible,


well I knew it was possible but a bit more difficult than just replacing a light switch with a dimmer switch.


and
was surprised when the fluorescents in my school lecture theatre could be
dimmed. They were probably installed in the early to mid 70s, which gives an
idea of what technology was available then.


I had a brief look at how the stage lighting in the school worked in the late 70s, just seemed to be large covered rheostats covered in dust.
A selection of coloured filters were in a cardboard box too.


I remember a huge cabinet about
the size of a 6-foot high freezer in the projection unit which gave off a
hell of a hum as the lights were going from full off to full on, which they
did on a timer: the lecturer pressed a button and they dimmed/brightened
automatically over the course of about 5 seconds.


Yes most of us have evolved since those days, in most cases we have better kit and better ways of doing things now.


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Old March 1st 19, 06:09 PM posted to uk.d-i-y
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"whisky-dave" wrote in message
...
On Friday, 1 March 2019 16:02:52 UTC, NY wrote:
"whisky-dave" wrote in message
...

Dimmable fluorescent fittings have been around since the early 1960s.
Nothing new there.


How are fluorescents dimmed?


I waqsnt; sure so looked it up.

https://www.etcconnect.com/Support/A...ures-Work.aspx

I'd always thought that it was impossible,


well I knew it was possible but a bit more difficult than just replacing a
light switch with a dimmer switch.


and
was surprised when the fluorescents in my school lecture theatre could be
dimmed. They were probably installed in the early to mid 70s, which gives
an
idea of what technology was available then.


I had a brief look at how the stage lighting in the school worked in the
late 70s, just seemed to be large covered rheostats covered in dust.


I helped with the lighting in the school hall (an older building with a
proper proscenium arch, wings and a curtain) and they used huge wire-wound
rheostats which were operated with a length of wood to fade many up or down
at the same time.

There was also a huge circular drum rheostat for dimming the house lights,
and we were given strict instructions to make *certain* that the big
circular handle was in the fully-anti-clockwise (min) position before
turning on or off (to avoid turning them on/off suddenly) and when we
started to fade them either way, do it *quickly*, taking no more than about
5 seconds to go from one end to the other (accompanied by a loud screeching
of the contact on the wire!) to avoid running the rheostat at part-load for
any longer than necessary. Even then, we could see the wire glowing in the
dim light of the wings where the lighting board was.

The lecture theatre was equipped with lots of theatrical lights, and a nice
"new" (at the time) triac dimmer system with tiny sliders for diming the
lights, but it was never used for plays because there were no wings (other
than exiting through the fire doors either side into the playground) and
there was no curtain.

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Old March 1st 19, 07:25 PM posted to uk.d-i-y
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In article ,
whisky-dave wrote:
On Friday, 1 March 2019 14:31:48 UTC, Dave Plowman (News) wrote:
In article ,
Brian Gaff wrote:
Could one ask why you would want to these days, assuming you could find
any to install!


Is it that far behind LEDs etc in terms of efficiency/life?


I've heard they are, but not having testd them myself I can't say.



A florry gives a more even illumination than a series of LEDs.


That's not really true espeacily over time, the ends of florrys go black
and start to flicker and get dimmer with time.


With old fashioned ballasts, possibly. But high frequency ones have been
around for many years now. The light output does go down slightly with
age, though.


Also a better selection of colour temperature, etc.


Not sure that is true, but it should be difficult for LED tubes to be desined like the phillips hues.


Many might prefer to have the colour temperature they want from the off
without messing about.

We have new LED tubes in our new lab auto on and off, in my office they
are also dimmable unlike the florrys in my present office, one of which
is just flickering. One in the corridor is flickering and making a
noise. It could wake the students up ;-)


Dimming florries with electronic ballasts has also been around for many a
year. The ones lighting my kitchen worktops - installed some 20 years ago.

--
*A bartender is just a pharmacist with a limited inventory.

Dave Plowman London SW
To e-mail, change noise into sound.
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Old March 1st 19, 07:27 PM posted to uk.d-i-y
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Default Fluorescent lighting

In article ,
charles wrote:
Dimmable fluorescent fittings have been around since the early 1960s.
Nothing new there.


Even earlier than that, Charles. Our school hall had them in the 50s.
Although not something that would fit in a one gang box. ;-)

--
*When it rains, why don't sheep shrink? *

Dave Plowman London SW
To e-mail, change noise into sound.


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Old March 1st 19, 07:28 PM posted to uk.d-i-y
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Default Fluorescent lighting

In article ,
whisky-dave wrote:
This lab was build in the 1960s last electrical refurbishment was in the
mid 90s. But still never seen any dimmable florescant in the dept or
uni, there must be a reason.


Generally, florries in a lab are working lights. Why would you need to dim
them?

--
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Dave Plowman London SW
To e-mail, change noise into sound.
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Old March 1st 19, 07:30 PM posted to uk.d-i-y
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Default Fluorescent lighting

In article ,
NY wrote:
"whisky-dave" wrote in message
...


Dimmable fluorescent fittings have been around since the early 1960s.
Nothing new there.


How are fluorescents dimmed? I'd always thought that it was impossible,
and was surprised when the fluorescents in my school lecture theatre
could be dimmed. They were probably installed in the early to mid 70s,
which gives an idea of what technology was available then. I remember a
huge cabinet about the size of a 6-foot high freezer in the projection
unit which gave off a hell of a hum as the lights were going from full
off to full on, which they did on a timer: the lecturer pressed a
button and they dimmed/brightened automatically over the course of
about 5 seconds.


With the electronic ballasts I have here, all you need to add is a simple
pot to dim them.

--
*Why are a wise man and a wise guy opposites? *

Dave Plowman London SW
To e-mail, change noise into sound.
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Old March 1st 19, 07:48 PM posted to uk.d-i-y
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Default Fluorescent lighting

On 01/03/2019 16:30, whisky-dave wrote:
On Friday, 1 March 2019 16:02:52 UTC, NY wrote:
"whisky-dave" wrote in message
...

Dimmable fluorescent fittings have been around since the early 1960s.
Nothing new there.


How are fluorescents dimmed?


I waqsnt; sure so looked it up.

https://www.etcconnect.com/Support/A...ures-Work.aspx

I'd always thought that it was impossible,


well I knew it was possible but a bit more difficult than just replacing a light switch with a dimmer switch.


It is basically replacing the light switch with a dimmer (suitable for
inductive loads), but you also need to add a separate pair of isolated
supplies to keep the filaments hot enough to continue operating in
thermionic emission mode when the tube current is too low to do it just
by itself. This will also enable the tube to strike without a starter.

Indeed, I made just such a light as a teenager.

Commercially, Transtar was a well known manufacturer of dimming magnetic
ballasts (and very high quality non-dimming ballasts).

and
was surprised when the fluorescents in my school lecture theatre could be
dimmed. They were probably installed in the early to mid 70s, which gives an
idea of what technology was available then.


One issue with banks of dimming fluorescents is all the tubes had to be
replaced together, otherwise newer and older tubes are significantly
different light output, and different makes can be different too.

Also, you get colour shift and a significant drop in CRI when dimming
fluorescents, as the ratio of light output from the different mercury
line changes, which upsets the colour balance from the arc and the
phosphor (tend to lose more green and end up with purple from the over
balance of red and blue).

Nowadays with microcontroller based electronic ballasts, adding dimming
is trivial, although it's not done by using triac dimmers. 0-10V, DALI,
switch-dim, or photocell to generate constant lux level are common, and
many electronic ballasts support multiple of these.

Indeed, many electronic ballasts support multiple different tubes that
run at different currents, and having identified the tube in use from
the electrical characteristics, effectively use the internal dimmer
logic to limit the current to the max allowed for the identified tube.

--
Andrew
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Old March 1st 19, 08:43 PM posted to uk.d-i-y
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Default Fluorescent lighting

In article ,
Dave Plowman (News) wrote:
In article ,
charles wrote:
Dimmable fluorescent fittings have been around since the early 1960s.
Nothing new there.


Even earlier than that, Charles. Our school hall had them in the 50s.
Although not something that would fit in a one gang box. ;-)


I can quite believe that, but I first met them in 1961.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle
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Old March 2nd 19, 03:37 AM posted to uk.d-i-y
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On Friday, 1 March 2019 09:05:08 UTC, Brian Gaff wrote:
Could one ask why you would want to these days, assuming you could find any
to install!

Even I managed to install the old type, you just screw them up connect them
up and they go!
Brian

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Note this Signature is meaningless.!
"Weatherlawyer" wrote in message
...
Is there a wiki on how to install fluorescent lighting


This may sound like a silly question
What?


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