Silent trailing edge dimmer/bulb compatibility

Would look for a modern design LED lamp that dosen`t insist on trailing edge dimming.

This is one of those theoretical things with little evidence to back it up, have programmed almost permanently dimmed halogen to have a `clean up` half hour sometime in week wher it runs at full power to scour deposited halogens back off glass. Didn`t seem to make much differnce to lamps that weren`t in the circuit and just ran at low check permanently.

There is a classic miscarriage of justice case where a man got jailed for murder by arson.

Years later it was proven that the `bulb saver` button diode style insert in a pendant lampholder had overheated and caused the fire.

Dimming is a better way of extending filament life.

Reply to
Adam Aglionby
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You may have been lucky. Had one early and expensive mains LED explode in a spectacular fashion and trip the breaker.

Reply to
Dave Plowman (News)

I've often read this - but it's not born out in practice. I have RO80 halogens in the kitchen which are often run dimmed. If that had a permanent effect, a single replacement would be rather obviously brighter than the old ones.

Halogen headlamps in a car (no dimmer) do age, though.

Reply to
Dave Plowman (News)

Ah - that's intersting. Could explain why the dimmable LEDs I bought recently work just fine on a 25 year old dimmer.

Reply to
Dave Plowman (News)

I've only ever had that happen with the cheaper CFL. non of my blown halgen s or LEDs have taken out the lighting circuit.

I've not found that. I brought a new light fitting with 6 halogen spotlig ht up in ~2007 last year one stopped working a couple of months later anoth er stioped working it was then when I went out to buy replacement 2 pack. I don;'t think nealry 10 years is that bad a lifetime. Whereas a friend has LV recessed and his last about 1-3 months and he repla ces them, non dimmed but I;ve said I think it's vibration as the kids play in a room above the kitchen.

Mine presently run from about 8pm to 1am at around half power M-F I can handle the shortened life of 9 years. But would prefer LEDs.

I don't have such bulbs, and in the gas fire that had them I rarely put the m on anyway as they are only for show.

It's only recently dimmable LEDs have been on sale at what I consider a rea sonable price for what you get. Althopugh I did buy 1 for £13 in 2001 it had separted RGB colour LEDS cycling through the spectrum in a crude way a bit like slow disco lighting it was only 3W it lasted 5 years or so.

My LEDs on the dimmer take about 1 second to come on it's suprising I still notice this and think come-on light where are you !

Reply to
whisky-dave

5W resistor would do for a 40W Fireglow bulb, but not for 60W.

Ordinary filament bulb lifetime can indeed be hugely extended by under-running, but the light output is proportional to the fourth power of the voltage. Reducing power by 20% means reducing light by 40%.

Reply to
Dave W

Why waste time get what works. Leading edge dimmers just don;t work well with low power LEDs because they use traics rather than MOSFETS and he like. Its lioke kitting a pub out with tea mugs or plastic glaas rather than glass mugs because you don't like the idea of broken glass.

Reply to
whisky-dave

Apparently, *some* LEDs

Really? Where did you read this?

Reply to
Dave Plowman (News)

formatting link

about halfway down.

Trailing-edge Dimmers (Reverse phase dimmers)

Trailing-edge dimmers are more sophisticated than leading-edge dimmers, and usually use a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) o r IGBT (Insulated Gate Bipolar Transistor) switch rather than a TRIAC and c oil. This benefits the user with smooth, silent dimming control, absent of any buzzing noise.

A trailing-edge dimmer has a lower minimum load (often 10W) than leading-ed ge dimmers, making it a better choice for dimming modestly sized low-powere d lighting circuits.

Particularly beneficial for incandescent and halogen bulbs is the ? soft start? feature in trailing-edge dimmers, which prevents filame nt bulbs from dying or exploding of thermal shock when first switched on.

Reply to
whisky-dave

Did you read the 'usually' bit?

Reply to
Dave Plowman (News)

nd usually use a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or IGBT (Insulated Gate Bipolar Transistor) switch rather than a TRIAC and coil. This benefits the user with smooth, silent dimming control, absent o f any buzzing noise.

edge dimmers, making it a better choice for dimming modestly sized low-powe red lighting circuits.

?soft start? feature in trailing-edge dimmers,

and most old leading edge dimmers. And it's not beneficial for vanilla fila ment.

en first switched on.

if only.

NT

Reply to
tabbypurr

Yep do you see the bit where it says 'rather than a TRAIC and coil'

Reply to
whisky-dave

and usually use a MOSFET (Metal Oxide Semiconductor Field Effect Transisto r) or IGBT (Insulated Gate Bipolar Transistor) switch rather than a TRIAC a nd coil. This benefits the user with smooth, silent dimming control, absent of any buzzing noise.

g-edge dimmers, making it a better choice for dimming modestly sized low-po wered lighting circuits.

??soft start? feature in trailing-edge dimmers,

Where does it say old leading edge dimmers. ?

when first switched on.

I've never had these problems in the 30 odd years of having dimmers so this wasn't why I brought trailing edge dimmers.

Reply to
whisky-dave

s, and usually use a MOSFET (Metal Oxide Semiconductor Field Effect Transis tor) or IGBT (Insulated Gate Bipolar Transistor) switch rather than a TRIAC and coil. This benefits the user with smooth, silent dimming control, abse nt of any buzzing noise.

ing-edge dimmers, making it a better choice for dimming modestly sized low- powered lighting circuits.

??soft start? feature in trailing-edge dimmers,

k when first switched on.

is wasn't why I brought trailing edge dimmers.

troll

Reply to
tabbypurr

Sory for the delay, I have been elsewhere this week.

They are the Scolmore/Click MD150 range used with their OVIA 5.5W GU10 LEDs. Now their tech department said they would dim to 25% as long as at least two lamps were fitted and the total load was not exceeded. This has turned out to be correct and so I just order 177 dimmable lamps!

Reply to
ARW

Wonder why it's taken so long to make LEDs which dimmed with a normal dimmer? To force people to buy new ones - since they have such a claimed long life?

Reply to
Dave Plowman (News)

yuo';d have to know how LEDs work in that there is an off time fropm 0 to about 1.2V then they are fully on at about 2V which doesn't leave much wiggle room for dimming. This is one of our skills labs the studetns use a pot to dim an LED.

Reply to
whisky-dave

An LED driven from DC via a suitable pot dims nicely. Once triggered. It may not start up on the lowest setting, though.

Reply to
Dave Plowman (News)

There you go, you have to wait until it's triggered so 50% of the rise time it's untriggered, doesnlt leave much as much for dimming.

You should also note that mains lighting isn't DC for most of us and that yuo can;t use a simple pot because of this. with 'AC" it's also easier to switch an LED off than switch it on because you don't have to worry about the trigger point, just switch it on then wait a while and switch it off, and that is why it costs a bit more and a bit more complex.

unless dimmed properly.

Reply to
whisky-dave

It's certainly dome with theatre lights

Reply to
charles

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