I know they're not supposed to be used with dimmer and electronic
switches, but what physically happens? (apart from flickering at
anything other than full power?

In article ,
Hooch writes:
I know they're not supposed to be used with dimmer and electronic
switches, but what physically happens? (apart from flickering at
anything other than full power?

It depends how the electronic control gear inside behaves when
operated outside its design criteria. Some seem to dim a little
and then go out, some don't dim at all and then go out, one early
one I tried dimed a bit and then got much brighter than normal.
If there's no filament lamp load also on the dimmer, then you are
also operating the dimmer well outside its design criteria, and
it probably won't be presenting steadily reducing RMS voltage as
you turn the knob.

The stupid thing is that dimmable CFLs have been manufactured for
years, but presumably there isn't any perceived demand for them in
the UK, given by the complete lack of availability here. The
nearest there is is a range of lamps which move between 4(?) power
levels each time you momentarily switch them off, which is rather
a pathetic compromise on the controllability of a standard dimmer.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Megaman do dimmable cfls: but to replace the 6 candle bulbs above our dining
table would be somewhere around £90 (And I doubt if they have the same shape
and size yet, though M are, as far as I have seen, the only ones to make a
replacement for 'golf ball' sized lamps - which seem to be going very well
so far though also very expensive... Sshh!)

Some controls like some photocell switches, still have some power available
even in the 'off' condition. This meant that when we changed our outside
lights to cfl some of them cycled on and off continuously, and the photo
switch soon packed up. (Interestingly the v expensive - and only available
in much too bright - cfls with built in photoswitches, were also very short
lived.) Changing to one of the large switch sensors as used in street lamps,
however, enabled us to run half a dozen cfls outdoors, off the same switch -
and using the same energy as just one of our previous bulbs...

Don't know if there is a similar switch based alternative for the dimming
problem though - sorry! Our dimmers don't seem to last very long even with
ordinary tungstens, in any case, and it is a real pain that the dimmer
modules themselves are not cheaply and individually available, even though
they are only held in with one nut and would be very easy for anyone to
change!

S


"Andrew Gabriel" wrote in message
...
In article ,
Hooch writes:
I know they're not supposed to be used with dimmer and electronic
switches, but what physically happens? (apart from flickering at
anything other than full power?

It depends how the electronic control gear inside behaves when
operated outside its design criteria. Some seem to dim a little
and then go out, some don't dim at all and then go out, one early
one I tried dimed a bit and then got much brighter than normal.
If there's no filament lamp load also on the dimmer, then you are
also operating the dimmer well outside its design criteria, and
it probably won't be presenting steadily reducing RMS voltage as
you turn the knob.

The stupid thing is that dimmable CFLs have been manufactured for
years, but presumably there isn't any perceived demand for them in
the UK, given by the complete lack of availability here. The
nearest there is is a range of lamps which move between 4(?) power
levels each time you momentarily switch them off, which is rather
a pathetic compromise on the controllability of a standard dimmer.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 12 Apr, 06:31, Hooch wrote:

I know they're not supposed to be used with dimmer and electronic
switches, but what physically happens? (apart from flickering at
anything other than full power?

There are 2 effects, on the bulb and on the dimmer.

The lamp input circuit is rectifier and reservoir, so the dimmer will
experience current surges every half cycle, which is liable to kill it
relatively quickly.

The lamp sees reduced peak voltage. What this does varies, but
typically limited degree of dimming plus much reduced lamp life.


NT

In article ,
"spamlet" writes:
"Andrew Gabriel" wrote in message
...
The stupid thing is that dimmable CFLs have been manufactured for
years, but presumably there isn't any perceived demand for them in
the UK, given by the complete lack of availability here. The
nearest there is is a range of lamps which move between 4(?) power
levels each time you momentarily switch them off, which is rather
a pathetic compromise on the controllability of a standard dimmer.

Megaman do dimmable cfls:

They are the 4(?) power level ones I referred to above.

Don't know if there is a similar switch based alternative for the dimming
problem though - sorry!

There are dimmers with better firing circuits which can handle
strange loads, but the standard CFL electronic ballast is simply
not dimmable by chopping up the mains waveform.

Our dimmers don't seem to last very long even with
ordinary tungstens, in any case, and it is a real pain that the dimmer
modules themselves are not cheaply and individually available, even though
they are only held in with one nut and would be very easy for anyone to
change!

If you're into electronics, the part which fails is the triac
semiconductor switch, which costs under a pound in one-off
quantities.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

"Andrew Gabriel" wrote in message
...
In article ,
Hooch writes:
I know they're not supposed to be used with dimmer and electronic
switches, but what physically happens? (apart from flickering at
anything other than full power?

It depends how the electronic control gear inside behaves when
operated outside its design criteria. Some seem to dim a little
and then go out, some don't dim at all and then go out, one early
one I tried dimed a bit and then got much brighter than normal.
If there's no filament lamp load also on the dimmer, then you are
also operating the dimmer well outside its design criteria, and
it probably won't be presenting steadily reducing RMS voltage as
you turn the knob.

The stupid thing is that dimmable CFLs have been manufactured for
years, but presumably there isn't any perceived demand for them in
the UK, given by the complete lack of availability here. The
nearest there is is a range of lamps which move between 4(?) power
levels each time you momentarily switch them off, which is rather
a pathetic compromise on the controllability of a standard dimmer.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

http://www.varilight.co.uk/index%20soon.htm

Adam

In message , spamlet
writes
Some controls like some photocell switches, still have some power
available even in the 'off' condition. This meant that when we changed
our outside lights to cfl some of them cycled on and off continuously,
and the photo switch soon packed up. (Interestingly the v expensive -
and only available in much too bright - cfls with built in
photoswitches, were also very short lived.) Changing to one of the
large switch sensors as used in street lamps, however, enabled us to
run half a dozen cfls outdoors, off the same switch - and using the
same energy as just one of our previous bulbs...

In the CFL's, if there is any leakage through a dimmer or even
capacitive coupling in the cabling, the internal capacitors can charge
up to the point where the light will pulse on as it discharges the
capacitor.

I've got a really sensitive LED lamp (that I built myself) which will
happily glow when an ordinary switch is off, due to the tiny current
that couples through the mains cabling.

--
Clive Mitchell
http://www.bigclive.com

In article ,
"ARWadsworth" writes:

http://www.varilight.co.uk/index%20soon.htm

Looks interesting. I wonder when they'll be available?

The high power factor is perhaps a give away to how they
work -- possibly simply no storage capacitor after the
mains rectifier. I've had CFL's where this had died, but
they continued to work (dimmer). The HF oscillator was
apparently capable of restarting 100 times a second OK.
Such a CFL should be dimmable in a phase control dimmer
over a reasonable proportion of its range. Appropriate
additional circuitry could provide filament heating
when the tube drops below a certain power level, or
they might be Cold Cathode CFL's.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 12/04/2007 21:03, Andrew Gabriel wrote:

In article ,
"ARWadsworth" writes:
http://www.varilight.co.uk/index%20soon.htm

Looks interesting. I wonder when they'll be available?

The varilight website has been saying "coming soon" for some time, but
the "on/off switch" version is available now and the "dimmer-switch"
version are expected in June from

http://www.e-tradecounter.co.uk/onli...e-Lamp-Bayonet

Thanks for the extra info Andrew. I had been given a note about that triac
before somewhere, but had not got round to Maplins to follow it up. As I
have been scavenging dimmers from 'shop seconds', and these usually turn out
to be the nasty 'turn on' rather than 'push on' versions, replacing the
triac seems a much better proposition! Now to wonder if those Varilight
possibilities are going to be in any way affordable...

Very interesting little thread this is turning out to be - as do so many on
the 'CFL debate'.

Cheers,

S


"Andrew Gabriel" wrote in message
...
In article ,
"spamlet" writes:
"Andrew Gabriel" wrote in message
...
The stupid thing is that dimmable CFLs have been manufactured for
years, but presumably there isn't any perceived demand for them in
the UK, given by the complete lack of availability here. The
nearest there is is a range of lamps which move between 4(?) power
levels each time you momentarily switch them off, which is rather
a pathetic compromise on the controllability of a standard dimmer.

Megaman do dimmable cfls:

They are the 4(?) power level ones I referred to above.

Don't know if there is a similar switch based alternative for the dimming
problem though - sorry!

There are dimmers with better firing circuits which can handle
strange loads, but the standard CFL electronic ballast is simply
not dimmable by chopping up the mains waveform.

Our dimmers don't seem to last very long even with
ordinary tungstens, in any case, and it is a real pain that the dimmer
modules themselves are not cheaply and individually available, even
though
they are only held in with one nut and would be very easy for anyone to
change!

If you're into electronics, the part which fails is the triac
semiconductor switch, which costs under a pound in one-off
quantities.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In message , spamlet
writes
Thanks for the extra info Andrew. I had been given a note about that
triac before somewhere, but had not got round to Maplins to follow it
up.

Be careful in your triac choice. Some have isolated tabs, some have
live tabs and there is a wide range of triggering currents used that are
often different for all four of the triggering quadrants except in
alternistors or some snubberless triacs where they can only be triggered
in three of the quadrants.

Most mass produced dimmers use specialist triacs to suit their design.
Use of a wrong triac could result in live heatsink metalwork or serious
damage to inductive loads if the triggering characteristics were wrong.

Sorry. Yes, a but technical, but there's no such thing as a Maplin
general purpose triac that fits all applications.

--
Clive Mitchell
http://www.bigclive.com

The Screwfix Electricians forum advised that Maplins BTA08
http://www.maplin.co.uk/Search.aspx?...UK54J&DOY=15m4

was the right one: is this true?

S


"Clive Mitchell" wrote in message
...
In message , spamlet
writes
Thanks for the extra info Andrew. I had been given a note about that
triac before somewhere, but had not got round to Maplins to follow it up.

Be careful in your triac choice. Some have isolated tabs, some have live
tabs and there is a wide range of triggering currents used that are often
different for all four of the triggering quadrants except in alternistors
or some snubberless triacs where they can only be triggered in three of
the quadrants.

Most mass produced dimmers use specialist triacs to suit their design. Use
of a wrong triac could result in live heatsink metalwork or serious damage
to inductive loads if the triggering characteristics were wrong.

Sorry. Yes, a but technical, but there's no such thing as a Maplin
general purpose triac that fits all applications.

--
Clive Mitchell
http://www.bigclive.com

On Sun, 15 Apr 2007 20:31:48 GMT, "spamlet"
mused:

The Screwfix Electricians forum advised that Maplins BTA08
http://www.maplin.co.uk/Search.aspx?...UK54J&DOY=15m4

was the right one: is this true?

I'd be surprised if it was.
--
Regards,
Stuart.

In message , spamlet
writes
The Screwfix Electricians forum advised that Maplins BTA08
http://www.maplin.co.uk/Search.aspx?...UK54J&DOY=15m4

was the right one: is this true?

That's isolated tab, but probably requires 50mA gate current. Whether
it would work depends on your dimmer circuitry.

At that price you're well on your way to a complete new dimmer.

--
Clive Mitchell
http://www.bigclive.com

In article ,
"spamlet" writes:
The Screwfix Electricians forum advised that Maplins BTA08
http://www.maplin.co.uk/Search.aspx?...UK54J&DOY=15m4

was the right one: is this true?

If you're contemplating this, you'll have to take the old
triac out, so look and see what its part number is.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 14/04/2007 19:53, Andy Burns wrote:

The varilight website has been saying "coming soon" for some time, but
the "on/off switch" version is available now

I thought I'd give these a try, arrived today, the 20W, 1200 lumen,
claimed eq. to 100W incandescent (though wikipedia says 100W is 1600
lumen, so presume this is the standard "soft tone" fudge factor?)

The on/off switch operated dimming operated smoothly over a wide range,
it claims to go down to 2% brightness, no whistles or hums from it while
doing so.

The colour changes noticibly throughout the dimming range, when full
brightness it is quite yellowish, as is dims down it goes quite a bit
colder (pinkish/purple) when at minimum brightness it is blueish/white,

at low brightness you can see the plasma slowly pulsing around the
spirals, not flickery as such, and not noticiable if the lamp is shaded,
but noticible when looking directly at it.

The lamp is a bit slower starting than a fairly new GE BIAX 15W, though
when it does come on it is without any flicker and without much slow
warming up.