LED Dimmer switches that are NOT soft start

[HawkEye244]

Hi all,
I recently fitted some downlights and will shortly be fitting dimmer switches. I used the varlight pro from screwfix in one room but it has a soft start. I read a review mentioning this so I was aware. However, I don't really like softstart and I would like the rest of the downlights in other rooms to run on dimmers that turn on and off without this feature.

Any advice or tips? Are these dimmers the sort of thing only sold in the electrical merchants ?
Many thanks

 

[HawkEye244]

Surprising lack of feedback on this. Perhaps I've asked a stupid question ?

 

[ericmark]

No, but the inrush with quartz would damage the control gear if not soft start so soft start became standard. The same may be true for LED, but not to same extent, the smoothing capacitor is normally after the capacitor used to limit current using the cheap method, but how the pulse width modulated work not sure, likely can't dim PWM anyway.

But the problem with LED is we don't know what is inside the lamp, at least until we break one open, so the dimmer manufacturer has to play safe and use soft start.

 

[HawkEye244]

Thanks Eric.
I've got some downlights that were fitted by a sparky in 2014 that are dimmable without a soft start This is what the dimmer looks like:
Any thoughts on this ?

 

[ericmark]

Around 1990 I started fitting dimming switches, but there were three problems, one ionisation when a bulb fails can take out dimmer with the heavy current (flash when bulb blows) and quartz lamps should not be dimmed it shortens their life, causing envelope to go black as too cool, and dimming fluorescent is complex so with the coming of the Compact fluorescent lamp (CFL) dimmers needed removing.

As the LED arrived we could again dim the lamp, however with a dimmer switch this did not change the colour, so did not give the same ambience found with the tungsten lamp. Also the LED has a longer life, so getting smart LED lamps has removed the need for most wall mounted dimmer switches, it allows the colour to also be changed giving the ambience found with the old tungsten.

However where one is using a chandelier with 8 bulbs it gets a bit expensive, but then the system used with the CFL can be used where the lamps are arranged in two groups, giving 1/3, 2/3 and all lamps.

Integration of remote controls, wall switches, and mobile phones is also now possible, so in my bedroom I can switch lights on/off at switch, with remote or phone and even set a time to genitally wake me as lights switch on.

Many smart bulbs default to full on, so dimming the GU10 bulbs in bedroom, once switched off at wall, on switching back on they do so maximum output.

Although dimming switches can have the master/slave arrangement, it seems a lot of effort to go to. And in the main the old dimmers were removed because they had failed, so seems better to have a bulb which simply unplugs when it fails to replace it, to a switch which needs the power removing to all lighting to change.

The problems getting a dimmer to work without a neutral has further caused problems, and also finding dimmers that will be compatible with the bulb. Even my simple smart on/off switch has a published list of bulbs which will work with it, and the list is flawed, I found the G9 bulbs in the list had a shimmer.

I would love to understand the shimmer better, it is clearly a miss match between bulb and dimmer switch rather than either being faulty, but I have a draw full of bulbs where I have been trying to find bulbs that work with electronic switches.

Even the length of wire ceiling rose to switch can change how the lights work, the capacitive link between the two wires was never a problem with tungsten, but I have had LED lamps which would not switch off, but stayed on dim. The EU said bulbs must be marked if they can't be dimmed, but it did not say how the lamp can be dimmed, I am sure the old variable transformer I have would dim most bulbs, but it is rather large, so we have leading and trailing edge, but nothing on the bulb package to say which should be used.

So today not a single dimmer switch left in service in my house.

The switch you show looks like a grid switch. Cheapest grid system seems to be LAP which I think is a screwfix special.

 

[JohnW2]

.... quartz lamps should not be dimmed it shortens their life, causing envelope to go black as too cool ...

Although now essentially moot due to the effective demise of halogen/quartz bulbs, we've been through this before and, as far as I can understand from all I've read ....

... in general, dimming an incandescent bulb greatly increases its life, by reducing filament temperature. However, in the case of halogens, as you imply, reduction in envelope temperature has a detrimental effect on 'lifespan'. However, my understanding is that dimming does (by reducing filament temp) still increase lifespan of a halogen, but not by as much as it would increase it if it were a non-halogen incandescent.

Having said that, I suppose it depends upon what you mean by 'lifespan''. I'm talking about the time until the filament fails, but you may think that it has 'come to the end of its life' when darkening of the envelope starts to occur.

Kind Regards, John

 

[ericmark]

The whole idea of the quartz envelope is the tungsten will not stick to the quartz as the quartz is too hot, but will instead return to the tungsten filament, over time it does not return even so some bits will get thinner and other bits thicker until the thin bit fails. If the quartz is too cool then the tungsten deposits on the quartz and turns the quartz black.

I have seen quartz bulbs that have turned black.

However I am sure there is a range of temperature where hot enough to stop tungsten adhering to quartz, but not hot enough to melt a part of the tungsten, but I do not know what the range was.

It is like the switching of lights on/off, we know this also reduces life, but no idea the point at which better not to switch off when not used, I know when traffic lights changed to vehicle sensed the new ones were all lit with quartz bulbs, and clearly these are being switched on/off a lot, although the red bulb had a shorter life, there was not much between green and amber for life of bulb.

For my slide projector there was a warm up and cool down and the bulb life it seems was extended by including this, which seems to be the reverse of what is said about dimming switches, so it does seem yes dimming to a red glow was bad, but dimming a small amount was good, and I know in my own house bulbs lasted longer when going through a dimmer likely due to the soft start.