I have a dimmer, with a slow-blow T1.6A fuse; the fuse blew when
connected to a lamp with an energy-saving light-bulb.

Is that normal behaviour?

Daniele

On Wednesday, 6 December 2017 18:56:22 UTC, D.M. Procida wrote:
I have a dimmer, with a slow-blow T1.6A fuse; the fuse blew when
connected to a lamp with an energy-saving light-bulb.

Is that normal behaviour?

Daniele

no


NT

In article
,
D.M. Procida wrote:
I have a dimmer, with a slow-blow T1.6A fuse; the fuse blew when
connected to a lamp with an energy-saving light-bulb.

Is that normal behaviour?

What sort of energy saving bulb? Any LED will normally work on a dimmer
circuit - but not dim unless a dimmable LED with compatible dimmer.

I've never tried a CFL.

--
*Speak softly and carry a cellular phone *

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

Huge wrote:

On 2017-12-06, D.M. Procida
wrote:
I have a dimmer, with a slow-blow T1.6A fuse; the fuse blew when
connected to a lamp with an energy-saving light-bulb.

gross generalisationEnergy saving bulbs are not dimmable./

I'm pretty sure this one isn't. I didn't expect the dimming to work, but
I didn't expect a fuse to blow either.

Daniele

Who knows these days. You don't say what sort of one it was, but many lamps
have inductors in the circuit so all sorts of stuff can happen.
I don't believe a standard dimmer can work on most energy saving systems.
Brian

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"D.M. Procida" wrote in
message
...
I have a dimmer, with a slow-blow T1.6A fuse; the fuse blew when
connected to a lamp with an energy-saving light-bulb.

Is that normal behaviour?

Daniele

The point is that dimmers work in one of two ways, they either reduce the
duty cycle at 50 hz, or employ a more sophisticated system of doing things
at the zero crossing point. I have no idea how the various power supplies in
other forms of lamp other than filament might react in these situations.
Brian

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Blind user, so no pictures please!
"D.M. Procida" wrote in
message
...
Huge wrote:

On 2017-12-06, D.M. Procida

wrote:
I have a dimmer, with a slow-blow T1.6A fuse; the fuse blew when
connected to a lamp with an energy-saving light-bulb.

gross generalisationEnergy saving bulbs are not dimmable./

I'm pretty sure this one isn't. I didn't expect the dimming to work, but
I didn't expect a fuse to blow either.

Daniele

The early (heavy) CFLs tended to work like old fashioned fluorescents did,
with a choke and capacitor etc, the newer ones have a switch mode psu
instead basically.
Brian

--
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"Dave Plowman (News)" wrote in message
...
In article
,
D.M. Procida wrote:
I have a dimmer, with a slow-blow T1.6A fuse; the fuse blew when
connected to a lamp with an energy-saving light-bulb.

Is that normal behaviour?

What sort of energy saving bulb? Any LED will normally work on a dimmer
circuit - but not dim unless a dimmable LED with compatible dimmer.

I've never tried a CFL.

--
*Speak softly and carry a cellular phone *

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

On Thursday, 7 December 2017 07:44:25 UTC, D.M. Procida wrote:
Huge wrote:

On 2017-12-06, D.M. Procida
wrote:
I have a dimmer, with a slow-blow T1.6A fuse; the fuse blew when
connected to a lamp with an energy-saving light-bulb.

gross generalisationEnergy saving bulbs are not dimmable./

I'm pretty sure this one isn't. I didn't expect the dimming to work, but
I didn't expect a fuse to blow either.

Daniele

If you connect a CR ballasted LED lamp to a triac or MOSFET dimmer, you'll get 100 large pulses of current a second. That will kill the LED lamp in short order, and might perhaps take out the fuse.

CR ballasted lamps are very dimmable, but not by chopping the waveform. A series capacitor is the easiest way to dim them. If you want several brightness levels, a switchbank and 2 capacitors would get you 4 levels + off.


NT

wrote in message
...
If you connect a CR ballasted LED lamp to a triac or MOSFET dimmer, you'll
get 100 large pulses of current a second. That will kill the LED lamp in
short order, and might perhaps take out the fuse.

I presume that dimmable LED lights (eg Philip Hue) are dimmed by varying the
mark:space ratio of a constant-frequency square wave within the low-voltage
DC circuitry (ie not by varying the pseudo-AC mains that is fed to the power
supply).

It ought to be possible to see the effect of dimming LEDs by illuminating a
desk fan. At full brightness the blades will be blurred (probably with sharp
edges as the LEDs turn on and off) and the area of blurring will become
shorter as the LED is dimmed and therefore turned on for a shorter period
within each pulsing cycle. This is probably easier to see if the fan speed
can be controlled (*) so it rotates at a sub-multiple of the pulsing
frequency and therefore becomes stationary.

I've seen interesting effects with fluorescent lamps and a desk fan: a sharp
blueish image caused by the visible components of the discharge and a more
blurred yellowish after-image caused by the decay of the fluorescence from
the phosphors.


(*) Either by varying the supply voltage to the fan or else by breaking H&S
rules and removing the guard so you can apply friction to the hub of the
blades and so slow it down a bit.

wrote:

On Thursday, 7 December 2017 07:44:25 UTC, D.M. Procida wrote:
Huge wrote:

On 2017-12-06, D.M. Procida
wrote:
I have a dimmer, with a slow-blow T1.6A fuse; the fuse blew when
connected to a lamp with an energy-saving light-bulb.

gross generalisationEnergy saving bulbs are not dimmable./

I'm pretty sure this one isn't. I didn't expect the dimming to work, but
I didn't expect a fuse to blow either.

Daniele

If you connect a CR ballasted LED lamp to a triac or MOSFET dimmer, you'll
get 100 large pulses of current a second. That will kill the LED lamp in
short order, and might perhaps take out the fuse.

Thanks, that's probably what happened.

CR ballasted lamps are very dimmable, but not by chopping the waveform. A
series capacitor is the easiest way to dim them. If you want several
brightness levels, a switchbank and 2 capacitors would get you 4 levels
+ off.

I think I'll just buy a new bulb! I was only testing a newly rewired
lamp.

Daniele

wrote in message
...
CR ballasted lamps are very dimmable, but not by chopping the waveform. A
series capacitor is the easiest way to dim them. If you want several
brightness levels, a switchbank and 2 capacitors would get you 4 levels +
off.

How are fluorescent tubes dimmed continuously (ie not in noticeable steps)?
I remember our lecture theatre at school (new in the late 1970s) had banks
of 2-tube lights which could be dimmed over a period of a few seconds from
full brightness to barely-lit, with no jumps in brightness apart from
between the dimmest brightness and fully-off. I remember there were racks of
electronics in the projection room which buzzed as the lights were dimmed
(but were silent at full brightness), though I can't remember now which
racks were used for dimming the fluorescent house lights and which were for
dimming the tungsten theatrical lights (I imagine the latter were
conventional triac dimmers).

As an aside, I also helped with the stage lighting for some of the school
plays in the main hall (as opposed to the lecture theatre which wasn't much
use for plays because it didn't have a proscenium arch and wings for the
off-stage actors to wait in) and the hall had a huge dimmer box with a
creaking rotary wheel to dim the tungsten house lights, and a rack of
sliding wire-wound dimmers for the various stage lights (as opposed to a
console of little sliders for the lecture theatre). I remember being warned
of three things: 1) dim the house lights *quickly* and do not leave them on
partially-dimmed for any longer than necessary, to avoid the dimmer
overheating; 2) when operating the master kill-switch for all the stage
lights (when an instant blackout was needed for theatrical effect), always
hit the switch with the wooden mallet provided, never with your hand,
because the switch gave off some fearsome arcs; 3) when turning on the stage
lights, always dim them from off, never by reversing the kill-switch or
you'll blow every bulb. A coordinated dim of multiple lamps involved a piece
of 2x1" wooden batten to move multiple faders in sync; the various lamp
circuits were wired by a patch panel so lights that those which needed to be
faded in sync were always on adjacent faders for that reason. That was real
heavy-engineering with everything big, hot and sparking :-) I remember the
carefully-balanced bucket of water above the stage, operated by a rope from
the lighting gallery, which was rigged as a surprise for the cast during the
curtain-call on the final night of one Gilbert and Sullivan opera - the
headmaster professed to be "not amused" and "took a very dim view of the
antics" afterwards when he bollocked us all :-)

In article ,
NY wrote:
How are fluorescent tubes dimmed continuously (ie not in noticeable
steps)? I remember our lecture theatre at school (new in the late
1970s) had banks of 2-tube lights which could be dimmed over a period
of a few seconds from full brightness to barely-lit, with no jumps in
brightness apart from between the dimmest brightness and fully-off. I
remember there were racks of electronics in the projection room which
buzzed as the lights were dimmed (but were silent at full brightness),
though I can't remember now which racks were used for dimming the
fluorescent house lights and which were for dimming the tungsten
theatrical lights (I imagine the latter were conventional triac
dimmers).

We had dimmable fluorescents too in our school hall. Someone's pet
project, given how little that facility was used. In the '50s.

The fluorescents in my kitchen dim. Special Osram electronic ballasts. The
dimmer control just a simple pot.

--
*IF YOU TRY TO FAIL, AND SUCCEED, WHICH HAVE YOU DONE?

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

On Thursday, 7 December 2017 13:31:25 UTC, NY wrote:
tabbypurr wrote in message
...

CR ballasted lamps are very dimmable, but not by chopping the waveform. A
series capacitor is the easiest way to dim them. If you want several
brightness levels, a switchbank and 2 capacitors would get you 4 levels +
off.

How are fluorescent tubes dimmed continuously (ie not in noticeable steps)?
I remember our lecture theatre at school (new in the late 1970s) had banks
of 2-tube lights which could be dimmed over a period of a few seconds from
full brightness to barely-lit, with no jumps in brightness apart from
between the dimmest brightness and fully-off. I remember there were racks of
electronics in the projection room which buzzed as the lights were dimmed
(but were silent at full brightness), though I can't remember now which
racks were used for dimming the fluorescent house lights and which were for
dimming the tungsten theatrical lights (I imagine the latter were
conventional triac dimmers).

As an aside, I also helped with the stage lighting for some of the school
plays in the main hall (as opposed to the lecture theatre which wasn't much
use for plays because it didn't have a proscenium arch and wings for the
off-stage actors to wait in) and the hall had a huge dimmer box with a
creaking rotary wheel to dim the tungsten house lights, and a rack of
sliding wire-wound dimmers for the various stage lights (as opposed to a
console of little sliders for the lecture theatre). I remember being warned
of three things: 1) dim the house lights *quickly* and do not leave them on
partially-dimmed for any longer than necessary, to avoid the dimmer
overheating; 2) when operating the master kill-switch for all the stage
lights (when an instant blackout was needed for theatrical effect), always
hit the switch with the wooden mallet provided, never with your hand,
because the switch gave off some fearsome arcs; 3) when turning on the stage
lights, always dim them from off, never by reversing the kill-switch or
you'll blow every bulb. A coordinated dim of multiple lamps involved a piece
of 2x1" wooden batten to move multiple faders in sync; the various lamp
circuits were wired by a patch panel so lights that those which needed to be
faded in sync were always on adjacent faders for that reason. That was real
heavy-engineering with everything big, hot and sparking :-) I remember the
carefully-balanced bucket of water above the stage, operated by a rope from
the lighting gallery, which was rigged as a surprise for the cast during the
curtain-call on the final night of one Gilbert and Sullivan opera - the
headmaster professed to be "not amused" and "took a very dim view of the
antics" afterwards when he bollocked us all :-)

That sort of pre-war stuff makes variac dimming seem high tech. There are various ways to dim fluorescents, most require a dimmable ballast but variacs and series caps can be used to a limited extent on old iron ballasts. But haven't been in many decades.


NT

NY wrote
wrote

If you connect a CR ballasted LED lamp to a triac or MOSFET dimmer,
you'll get 100 large pulses of current a second. That will kill the LED
lamp in short order, and might perhaps take out the fuse.

I presume that dimmable LED lights (eg Philip Hue) are dimmed by varying
the mark:space ratio of a constant-
frequency square wave within the low-voltage DC circuitry

Much more likely by varying the current thru the
leds with a programmable current regulator.

(ie not by varying the pseudo-AC mains that is fed to the power supply).

Yeah, that would be a stupid way to do it.

It ought to be possible to see the effect of dimming LEDs by illuminating
a desk fan. At full brightness the blades will be blurred (probably with
sharp edges as the LEDs turn on and off) and the area of blurring will
become shorter as the LED is dimmed and therefore turned on for a shorter
period within each pulsing cycle. This is probably easier to see if the
fan speed can be controlled (*) so it rotates at a sub-multiple of the
pulsing frequency and therefore becomes stationary.

Problem is that while I have a number of Hue bulbs,
I dont have any type of fan, desk or otherwise.

I've seen interesting effects with fluorescent lamps and a desk fan: a
sharp blueish image caused by the visible components of the discharge and
a more blurred yellowish after-image caused by the decay of the
fluorescence from the phosphors.

I might see if what you lot call the pound shops or aliexpress
have a cheap one. Only $1.40, it will be a month coming tho.

(*) Either by varying the supply voltage to the fan or else by breaking
H&S rules and removing the guard so you can apply friction to the hub of
the blades and so slow it down a bit.

On Thursday, 7 December 2017 22:41:02 UTC, Rod Speed wrote:
NY wrote
tabbypurr wrote

If you connect a CR ballasted LED lamp to a triac or MOSFET dimmer,
you'll get 100 large pulses of current a second. That will kill the LED
lamp in short order, and might perhaps take out the fuse.

I presume that dimmable LED lights (eg Philip Hue) are dimmed by varying
the mark:space ratio of a constant-
frequency square wave within the low-voltage DC circuitry

Much more likely by varying the current thru the
leds with a programmable current regulator.

which is achieved
by varying
the mark:space ratio of a
square wave within the low-voltage DC circuitry


Problem is that while I have a number of Hue bulbs,
I dont have any type of fan, desk or otherwise.

I'm pretty sure your problem is something else


NT

On Thursday, 7 December 2017 23:11:58 UTC, wrote:
On Thursday, 7 December 2017 22:41:02 UTC, Rod Speed wrote:
NY wrote
tabbypurr wrote

If you connect a CR ballasted LED lamp to a triac or MOSFET dimmer,
you'll get 100 large pulses of current a second. That will kill the LED
lamp in short order, and might perhaps take out the fuse.

I presume that dimmable LED lights (eg Philip Hue) are dimmed by varying
the mark:space ratio of a constant-
frequency square wave within the low-voltage DC circuitry

Much more likely by varying the current thru the
leds with a programmable current regulator.

which is achieved
by varying
the mark:space ratio of a
square wave within the low-voltage DC circuitry


Problem is that while I have a number of Hue bulbs,
I dont have any type of fan, desk or otherwise.

I'm pretty sure your problem is something else


NT

The old dimmable fluorescent lamp systems used separate transformers to
feed the filaments at each end. This ensured that there was always a
high enough filament temperature to prevent flickering at low light
levels.

The newer dimmers that are suitable for LEDs and CF lamps use trailing
edge switching of the mains waveform. The advantage of this is that the
rising edge of each half cycle has the normal slope thereby avoiding
a massive current peak which would occur with leading edge switching
when capacitors are charged.

John

On 06/12/2017 20:15, wrote:
On Wednesday, 6 December 2017 18:56:22 UTC, D.M. Procida wrote:
I have a dimmer, with a slow-blow T1.6A fuse; the fuse blew when
connected to a lamp with an energy-saving light-bulb.

Is that normal behaviour?

Daniele

no

It might be if you are out of luck, it is the wrong sort of leading edge
dimmer and you hit the peak voltage in a cycle at first switch on. The
worst case peak inrush current might be enough to take down a nominally
slow-blow fuse. I'd expect it to last a few on off cycles though.

LED bulbs are tetchy about which dimmers they will work with and older
dimmers can fail at least two ways - they don't like the much lower load
presented by the LED bulb (minimum load for stability not met) or they
cut the wrong part off the mains waveform leading to component stress.

Worst case the LED control electronics ends up drawing ever more current
from the dimmer to try and maintain constant brightness. This may well
blow the fuse for some partial brightness setting on the dimmer.

Even quite expensive dimmers that claim to do it right seem to be prone
to premature failure from what I have seen. A friend with some expensive
ones has got through 3 or 4 under warrantee now. The makers admitted
some sort of batch fault so maybe he was just unlucky.

--
Regards,
Martin Brown

wrote in message
...
On Thursday, 7 December 2017 22:41:02 UTC, Rod Speed wrote:
NY wrote
tabbypurr wrote

If you connect a CR ballasted LED lamp to a triac or MOSFET dimmer,
you'll get 100 large pulses of current a second. That will kill the
LED
lamp in short order, and might perhaps take out the fuse.

I presume that dimmable LED lights (eg Philip Hue) are dimmed by
varying
the mark:space ratio of a constant-
frequency square wave within the low-voltage DC circuitry

Much more likely by varying the current thru the
leds with a programmable current regulator.

which is achieved
by varying
the mark:space ratio of a
square wave within the low-voltage DC circuitry


Just so I understand the quoting here, are you saying that I was right that
the lamp is dimmed by varying the mark:space ratio which has the effect of
varying the (average) current through the LEDs?

On 08/12/2017 09:24, NY wrote:
wrote in message
...
On Thursday, 7 December 2017 22:41:02 UTC, Rod SpeedÂ* wrote:
NY wrote
tabbypurr wrote

If you connect a CR ballasted LED lamp to a triac or MOSFET dimmer,
you'll get 100 large pulses of current a second. That will kill
the LED
lamp in short order, and might perhaps take out the fuse.

I presume that dimmable LED lights (eg Philip Hue) are dimmed by
varying
the mark:space ratio of a constant-
frequency square wave within the low-voltage DC circuitry

Much more likely by varying the current thru the
leds with a programmable current regulator.

which is achieved
by varying
the mark:space ratio of a
square wave within the low-voltage DC circuitry


Just so I understand the quoting here, are you saying that I was right
that the lamp is dimmed by varying the mark:space ratio which has the
effect of varying the (average) current through the LEDs?

Yes.

They are adjusted by pulse width modulation at a frequency high enough
that persistence of vision can't see it. It is highly efficient.

The frequency need not be particularly constant either so long as it is
never slow enough to show visible flicker. The yellow phosphor is a bit
slower than the blue LED so if there is any strobe effect visible on
moving objects it will be most obvious in the blue channel.

Some LED based traffic lights and brake lights do show bad flicker in
peripheral vision. I find it annoying.

--
Regards,
Martin Brown

"Martin Brown" wrote in message
news
They are adjusted by pulse width modulation at a frequency high enough
that persistence of vision can't see it. It is highly efficient.

The frequency need not be particularly constant either so long as it is
never slow enough to show visible flicker. The yellow phosphor is a bit
slower than the blue LED so if there is any strobe effect visible on
moving objects it will be most obvious in the blue channel.

Some LED based traffic lights and brake lights do show bad flicker in
peripheral vision. I find it annoying.

I can see multiple images with our LED lights, especially if I look from one
object to another on the other side of the room and there is an LED lamp in
the way.

Some car tail/brake lights are distracting, especially if you can see them
out of the corner of your eye on a car going in the opposite direction so
the closing speed is quite high. The thing that was really bad (until they
fixed it) was the red/green man on the push-button boxes at pelican
crossings - they evidently used a slower pulse speed than in other
situations where LEDs were used.

Mind you, the worst example I saw was with the old pre-LED vacuum tube
displays they you got on calculators etc. We stayed in a holiday cottage
once, not that long ago, and a fairly modern cooker used that sort of
display as the clock on the oven. And that had appalling flicker. You could
even see it if you looked straight-on at it (no need for peripheral vision)
and if you moved your eyes over it you saw a whole string of after-images of
the time trailing behind it in your field of vision. I wouldn't be surprised
if it was being pulsed at mains frequency, rather than several hundred or
thousand Hertz as they usually use with pulsed displays.

On Friday, 8 December 2017 09:24:44 UTC, NY wrote:
tabbypurr wrote in message
...
On Thursday, 7 December 2017 22:41:02 UTC, Rod Speed wrote:
NY wrote
tabbypurr wrote

If you connect a CR ballasted LED lamp to a triac or MOSFET dimmer,
you'll get 100 large pulses of current a second. That will kill the
LED
lamp in short order, and might perhaps take out the fuse.

I presume that dimmable LED lights (eg Philip Hue) are dimmed by
varying
the mark:space ratio of a constant-
frequency square wave within the low-voltage DC circuitry

Much more likely by varying the current thru the
leds with a programmable current regulator.

which is achieved
by varying
the mark:space ratio of a
square wave within the low-voltage DC circuitry


Just so I understand the quoting here, are you saying that I was right that
the lamp is dimmed by varying the mark:space ratio which has the effect of
varying the (average) current through the LEDs?

all switched mode PSUs work like that. What I was saying is that Rod is a time wasting iriot. Which, after an extra second's though, I realised does not need saying.

wrote in message
...
On Thursday, 7 December 2017 22:41:02 UTC, Rod Speed wrote:
NY wrote
tabbypurr wrote

If you connect a CR ballasted LED lamp to a triac or MOSFET dimmer,
you'll get 100 large pulses of current a second. That will kill the
LED
lamp in short order, and might perhaps take out the fuse.

I presume that dimmable LED lights (eg Philip Hue) are dimmed by
varying
the mark:space ratio of a constant-
frequency square wave within the low-voltage DC circuitry

Much more likely by varying the current thru the
leds with a programmable current regulator.

which is achieved
by varying
the mark:space ratio of a
square wave within the low-voltage DC circuitry


Problem is that while I have a number of Hue bulbs,
I dont have any type of fan, desk or otherwise.

I'm pretty sure your problem is something else

Any 2 year old could leave that for dead, gutless.