light dimmer leading/trailing edge

[alan_m]

I've just installed a new light fitting with dimmable LED bulbs and it's
connected to an existing light dimming switch.

The bulbs don't dim at all, just stay at full brightness.

Is this the expected behaviour of a bulb that requires trailing edge
dimming but is connected to a leading edge dimmer switch or should I
expect some form of step dimming or flickering?

Previously the dimmer worked with the LED bulb fitted in the old light
fitting but this new one only takes the smaller E14 bulbs where there
seems less choice for the dimmable versions.

The easiest option for me would be to possibly fit a trailing edge
dimmer switch rather than try and find a working bulb to work with the
existing switch.

[Andy Burns]

Post by alan_m
I've just installed a new light fitting with dimmable LED bulbs and it's
connected to an existing light dimming switch.
The bulbs don't dim at all, just stay at full brightness.
Is this the expected behaviour of a bulb that requires trailing edge
dimming but is connected to a leading edge dimmer switch or should I
expect some form of step dimming or flickering?
Previously the dimmer worked with the LED bulb fitted in the old light
fitting but this new one only takes the smaller E14 bulbs where there
seems less choice for the dimmable versions.
The easiest option for me would be to possibly fit a trailing edge
dimmer switch rather than try and find a working bulb to work with the
existing switch.

I've had better success with the v-Pro dimmers, than MK LED-specific
dimmers (flickery) the v-pro can be 'programmed' to different modes to
suit the lamps.

[Theo]

Post by Andy Burns

Post by alan_m
I've just installed a new light fitting with dimmable LED bulbs and it's
connected to an existing light dimming switch.
The bulbs don't dim at all, just stay at full brightness.
Is this the expected behaviour of a bulb that requires trailing edge
dimming but is connected to a leading edge dimmer switch or should I
expect some form of step dimming or flickering?
Previously the dimmer worked with the LED bulb fitted in the old light
fitting but this new one only takes the smaller E14 bulbs where there
seems less choice for the dimmable versions.
The easiest option for me would be to possibly fit a trailing edge
dimmer switch rather than try and find a working bulb to work with the
existing switch.

I've had better success with the v-Pro dimmers, than MK LED-specific
dimmers (flickery) the v-pro can be 'programmed' to different modes to
suit the lamps.

+1. Basically dimmable LEDs are a hack. The LED driver notices the mangled
mains waveform from the dimmer and works out how much to dim the LED. If
the mains waveform doesn't match what the bulb is expecting it won't dim,
and cheaper LEDs won't have enough energy storage to keep going through a
mains cycle and may flicker.

So when you change the lamps you need to set the dimmer to something they
expect. Different modes on the dimmer can be helpful here.

Another option is to fit one halogen bulb in the fitting which gives a more
continuous current waveform through the whole cycle. I have a V-Pro dimmer
with some dimmable GU10s and without that they flicker at low dim settings.

Theo

[Harry Bloomfield Esq]

Post by Theo
Another option is to fit one halogen bulb in the fitting which gives a more
continuous current waveform through the whole cycle. I have a V-Pro dimmer
with some dimmable GU10s and without that they flicker at low dim settings.

I bought a pair of dimmer switches, which claim to be able to self
adjust, to suit either leading, or trailing edge dimmable LED lamps. I'm
not clear how that works?

These were to replace a pair of ancient dimmers, which had continued to
work fine, after I had swapped the lamps from halogen, to dimmable LED,
but the LED lamps were just too low wattage. I replaced them with higher
wattages, but then they no longer dimmed, so time for new dimmers to suit.

[Brian]

Post by alan_m
I've just installed a new light fitting with dimmable LED bulbs and it's
connected to an existing light dimming switch.
The bulbs don't dim at all, just stay at full brightness.
Is this the expected behaviour of a bulb that requires trailing edge
dimming but is connected to a leading edge dimmer switch or should I
expect some form of step dimming or flickering?
Previously the dimmer worked with the LED bulb fitted in the old light
fitting but this new one only takes the smaller E14 bulbs where there
seems less choice for the dimmable versions.
The easiest option for me would be to possibly fit a trailing edge
dimmer switch rather than try and find a working bulb to work with the
existing switch.

In general, trailing edge dimmers are recommended for LED bulbs but some
are fine with leading edge ones. The LE dimmers were fitted ( about) 1998
so long before LED bulbs were around.

We used LE ones with some LED bulbs - IKEA large globes ( I think 120W
equivalent) and 3 40W equivalents in wall lights without issues in two
rooms. ( We originally used ordinary bulbs - I fitted LED ones once they
became available.)

When one of the IKEA globes failed - after a several years- I bought a
dimmable globe of Amazon ( in fact a pack of 3). They were hopeless.
Erratic dimming and like a cigarette end. I returned them.
I ordered some non- globe dimmables, which are fine.

[Max Demian]

Post by alan_m
I've just installed a new light fitting with dimmable LED bulbs and it's
connected to an existing light dimming switch.
The bulbs don't dim at all, just stay at full brightness.

This is a good argument for a 12V DC supply for lighting. Then PWM
dimmers can be employed.