Led house lights

Sam Vimes

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Sep 7, 2020
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I had reason today to look over the specification we wrote when planning to build our own house in 2009/10

We wanted LED lights throughout. GU10 7W -some dimmable, some not. At that time there wasn't much choice and the only option we came up with was from Philips. Each bulb cost £28 and some pennies. In the 15/16 years we have only had one bulb die and that was early in its life.

By comparison, today you can get a pack of 5 for less than half that price. The march of progress is quite illuminating at times.
 
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JTQ

May 7, 2005
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Much of technology has become relatively cheaper, more basic stuff like a beer or a decent meal out have gone completely the opposite way.

I also purchased additional LED bulbs this weekend. Here where and what you buy, major brand vs unknown affect what you pay though as you found, much cheaper than they were.

Have others noticed the massive drop in camping targeted solar panels compared to 2006?
 
Oct 8, 2006
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For a start, LED bulbs are often quote as 25000 hours life. Indeed the LEDs will last that long or even much longer, but the electronics that drive the LEDs my expire in a very very much shorter time. If you want to see why, look at one of your bulbs that is switched on through the viewfinder of a digital camera (it usually doesn't show up on a mobile phone camera) and you will see that the LEDs are either flashing on and off sequentially (the LEDs in the bulb housing are mounted in a ring) or they all go on and off simultaneously.

As for dimming, don't go and pay stupid prices for 'dimmable' bulbs - you can do it much more easily.

Mains electricity actually is a sinusoidal waveform so it passes through zero twice for each cycle, so 100 times a second. The bulb filament however has a significantly long thermal lag so the element will glow for much longer than the waveform takes to do a cycle and thus to the human eye looks continuous. (The latency of the human eye will cause any continuously flashing light source shorter than about 1/12sec as continuous. This is why a TV screen looks like a steady picture when in fact the whole picture is being rebuilt once every 1/25th of a second.)

Thinking of dimmers driving such lamps, in the first half of the waveform if the electronic switch is switched on almost as soon as the waveform starts rising the filament will start to glow and eventually reach peak light output. However if the point at which the electronic switch turns on is delayed by a short time the amount of power getting to the filament in that first half cycle will be reduced (it will be on for less time) and the bulb will appear to be radiating less light, i.e. it is dimmed. Filament bulbs often used to pop off with such dimmers* as at the point that the electronic switch turns on the voltage supplied (instead of being a gentle rise from near zero) will go from 0V to say 100V or more in around 2uS generating a huge surge shock to the filament which fails. The electronics inside LED lamps don't like it up 'em either. (*Unless the dimmer always switches on at full and has to be turned down.)

The simple solution is to use a 'trailing edge' dimmer. This type of electronic switch is always on at the start of a half cycle but is switched off before the half cycle ends. The average power supplied to the lamp is thus reduced and it dims, but there is no possibility of a thermal shock. As an aside it also means that the dimmer radiates less electrical interference. Trailing edge dimmers are nowadays often the same price as a leading edge dimmer and are readily available from such as Toolstation and Screwfix.

Because the electricity supply is being switched off by the dimmer it will work with any type of lamp, LED or filament.

HTH
 
May 30, 2024
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I had reason today to look over the specification we wrote when planning to build our own house in 2009/10

We wanted LED lights throughout. GU10 7W -some dimmable, some not. At that time there wasn't much choice and the only option we came up with was from Philips. Each bulb cost £28 and some pennies. In the 15/16 years we have only had one bulb die and that was early in its life.

By comparison, today you can get a pack of 5 for less than half that price. The march of progress is quite illuminating at times.
Coincidentally whilst at my son's house today, we spent a bit of time replacing and swapping around GU10 LED lamps. Aesthetics, power, colour temperature - trying to get them looking a bit consistent. (There are dozens in the house, and over time looking a bit random).

It struck me that the majority of the original 15 year old Phillips lamps were still good - much heavier, much greater quality feel. Intervening replacements have often only lasted about 12 months before starting to flicker.

That is the basic problem with quality and pricing - consumers are so focussed on minimum initial cost that manufacturers are obliged to throw everything at cost reduction to the detriment of durability. Progress of a sort, but I often wish there was more possibility to choose better quality.
 

Sam Vimes

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Its worth pointing out that the actual LED - the bit that produces the light - isn't connected directly to the mains supply. There will be a control circuit inside that takes the mains volltage down to a suitable DC voltage for use by the actual LEDS.

Its the control circuitry that can cause problems when used with a dimmer switch. I've tried non-dimmable LED lamps with a dimmer and they just don't work well. Those which are designed for dimming do.

Some cheaper ones may just try to reduce the DC voltage at the LED, better one may use pulse width modulation techniques.

Its fair to say though that my original Philips lamps dimmed very well but the cheapy ones I've tried have variable results.

In all honesty, while we specified dimmable LED lamps we found we never actually dimmed them and I removed the dimmer switches and replace them with a regular on/off switch.
 
Oct 8, 2006
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Its worth pointing out that the actual LED - the bit that produces the light - isn't connected directly to the mains supply. There will be a control circuit inside that takes the mains volltage down to a suitable DC voltage for use by the actual LEDS.

Its the control circuitry that can cause problems when used with a dimmer switch. I've tried non-dimmable LED lamps with a dimmer and they just don't work well. Those which are designed for dimming do.

Some cheaper ones may just try to reduce the DC voltage at the LED, better one may use pulse width modulation techniques.

Its fair to say though that my original Philips lamps dimmed very well but the cheapy ones I've tried have variable results.

In all honesty, while we specified dimmable LED lamps we found we never actually dimmed them and I removed the dimmer switches and replace them with a regular on/off switch.

Sam
Suggest you read my #3 about dimmers. If you get a trailing edge dimmer from the likes of Toolstation (71663) or Screwfix (123PM) they will dim any bulb, filament or LED.
 

Sam Vimes

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Sep 7, 2020
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I already used trailing edge dimmer switches specifically design for LED lamps, and for both resistive and inductive loads - but results varied.

As I previously mentioned, they had no problems with the Philips LED lamps but some of the cheaper ones I tried out of curiousity didn't respond well.

We have three series, seperately dimmable, each of which has three led lights in the string and the Philips ones would all dim equally and without any flicker or noticeable change in colour. With the cheaper ones I tried, they all dimmed at varying amounts and some went completely dark while others stayed dimmed - some flickered as they dimmed.

Trailing edge is definitely better in general but not all LED lamps are equal.
 
Apr 23, 2024
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As mentioned in another thread some led drivers do pulse them and others use constant current , which may explain the difference in response to mains dimmers , leading edge, trailing edge (phase angle) or burst-fire types. The other issue is that a triac which is used as the output device has a minimum holding current below which it will switch off , the higher the power rating the higher this 'hold on' current' is and as a lot of standard domestic dimmers are 300W rated and as the LED takes less than the holding current even at about 50% of the mains voltage(as it goes through its cycle) can cause curious effects such as flickering as the two controllers (mains dimmer and LED driver) fight each other .Replacing the triac with a lower power version can mitigate this incompatibility ( they are now producing commercial domestic dimmers with the lower rated triacs, specifically for LEDs) .Also some mains powered LED drivers only use half wave rectification (cheapness again) so on dimmers every 10ms the LEDs are Off.. Some of the 'better drivers are in fact switch mode power supplies and the dimmer input reduces the D.C output current to LED string.
 

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