Hi Chaps
I got a couple of these new dimmable gls led bulbs

like this
https://www.bltdirect.com/product.php?pid=27368

and they work ok, but when at full brightness I can still see a flicker
in the light output.

they are in two fittings either side of an archway with a single dimmer
running them both. This has always worked well for any other dimmable
bulbs like normal old fashioned incandescents or those slightly lower
power halogen replacements. Not so well for the flourescent dimmable gls
bulbs because of the fluorescent current threshold problem.

Does the team think its a basic problem with led bulbs and dimmers or my
particular arrangement in this case?

In which case should I have a dimmer for each fitting instead?

dedics

dedics wrote:

I got a couple of these new dimmable gls led bulbs

and they work ok, but when at full brightness I can still see a flicker
in the light output.

Does the team think its a basic problem with led bulbs and dimmers or my
particular arrangement in this case?

A friend has had his kitchen done, including lots of dimmable LED
down-lighters, I know I'd find the flicker difficult to live with, the
LEDs obviously react far quicker to 100 pulses per second than a
filament, can you get a high frequency dimmer, I wonder?

In article ,
dedics writes:
Hi Chaps
I got a couple of these new dimmable gls led bulbs

like this
https://www.bltdirect.com/product.php?pid=27368

and they work ok, but when at full brightness I can still see a flicker
in the light output.

they are in two fittings either side of an archway with a single dimmer
running them both. This has always worked well for any other dimmable
bulbs like normal old fashioned incandescents or those slightly lower
power halogen replacements. Not so well for the flourescent dimmable gls
bulbs because of the fluorescent current threshold problem.

Does the team think its a basic problem with led bulbs and dimmers or my
particular arrangement in this case?

In which case should I have a dimmer for each fitting instead?

Two possible problems:

1)
It's a basic problem with retrofit LED replacements, running from
conventional (filament lamp) dimmers.

LEDs are very easily dimmed using dimming controllers to drive them
directly. I'm guessing you have a regular filament lamp dimmer, and
then retrofit dimming LEDs which have been designed to run from a
filament lamp dimmer. The LEDs don't have the thermal inertia of a
filament lamp, and the power supplies in the dimming ones have no
DC smoothing (which would prevent them from dimming), so you are
seeing the chopped (phase control) waveform from the dimmer.

2)
The load on the dimmer is lower than it's lowest working rating
(often something like 40W). This usually causes the lamps to become
unstable and flicker when dimmed below a certain point.



What you want are some fittings with raw LED connections which use
an external LED controller. Then use a dimming LED controller. You
can normally string several LEDs together in series to run off a
single LED controller. The controller delivers constant current
(normally 350mA or 700mA, to match the LEDs in use), and a max
voltage or power rating which governs the max number of LEDs it
can drive in a series loop. Dimming LED drivers work by reducing
the drive current rather than chopping it (or may chop at many
kHz which your eyes can't see). The control is usually via a 10k
potentiometer and/or 10V dimming signal. Standard patress plates
with 10k pots are available as a standard component to use with
10V dimming controllers (fluorescent lamp and LED types).

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

On Mon, 25 Jun 2012 11:22:57 +0100, dedics
wrote:

like this
https://www.bltdirect.com/product.php?pid=27368

60W alternative, my arse. More like 50W, if you're lucky.
I'm sick and fed up and fecking annoyed at the dishonesty of these
lighting companies.

Grimly Curmudgeon wrote:
On Mon, 25 Jun 2012 11:22:57 +0100, dedics
wrote:

like this
https://www.bltdirect.com/product.php?pid=27368

60W alternative, my arse. More like 50W, if you're lucky.
I'm sick and fed up and fecking annoyed at the dishonesty of these
lighting companies.

eco-

A prefix designating that whatever follows is an outright lie. OED.


--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.