Why would you want the colour temperature of an LED to drop as it is dimmed? I know it is an unavoidable side-effect of dimming a tungsten bulb, but I don't see why you would want it to happen unless you couldn't avoid it. I like the fact that LEDs keep the same colour as they dim. I just wish LED bulbs could be dimmed further: most bulbs (eg Philips Hue) have a minimum brightness below which they go out altogether. It makes them less useful as a very dim night light.
But that might just get you a bulb that can be toggled between cool and warm white.
except cool would normally be in excess of 3500K. 2200K is a very warm white.
This depends on the situation.
The beauty of design, is keeping an open mind.
Paul
yes, well, the ikea ones are fairly limited too, 4400K I think is "moonlight" I'd prefer they went higher, and 2200K is "candlelight"
Well you could buy one, swap it one when a bulb goes, then rinse and repeat. Hopefully there comes a time where you don't need to swap them again for a very long time. So you get a convenience payback as well as energy reduction :-)
I have found the only real way to find decent lamps where there is a very specific use case, is to just buy the odd one on spec now and then and see how it performs.
That Philips one I go particularly because I wanted a dimmable that could project a bit of light upwards when installed in a cap down fitting - to get a bit more diffuse bounce back off the white ceiling. So the dimming range and colour temp shift came as a pleasant surprise. I replaced the other 7 to match in the end.
So you want an LED that behaves like an incandescent? Bit like wanting CDs to have scratches recorded on them!
The only time I miss the change in colour of incandescents is LED torches which get dimmer and dimmer without it being obvious that the batteries are depleted.
It's hard to tell if an LED torch battery is getting flat as they just get dimmer without the tell tale yellow effect.
It's a matter of whether you like economy and dislike smoke arising from the circuit.
Yes. Why is that so hard to understand?
Not in the slightest. LED bulbs are replacing incandescent bulbs which have always got ?warmer? as they are dimmed. I like this, I don?t regard it as a ?fault? but a feature that I?m used to and like. It?s often why I use a dimmer, to create a lower but warmer level of light for the ambience.
Tim
Which bit of ?they look ghastly? did you fail to understand, or does your opinion someway trump my opinion?
If you like cold dim light fine, I don?t.
Tim
Well some dimming seems to be duty cycle related ie its pulsing on and off, but I guess resistive dimming by lowering its voltage will be pretty inefficient too. Brian
If you're referring to SMPS problems at low voltage, an SMPS is supposed to have UVLO. It's not our fault if a necessary safety feature is missing.
SMPS run at constant power. As the voltage is dropped on input, the current on the primary side rises. If allowed to go unchecked, the current flow could be too much for components on the primary side. "Under voltage lockout" prevents that. Even mains distribution can deliver the wrong voltage (it happened here at the house one day), and devices in your house should be protected. Unfortunately, there's nothing for motors, and motors can be damaged with too low or too high of a voltage. But an SMPS (switch mode power supply, like in the base of high power LEDs), there is room in the silicon for all sorts of features, and no excuses.
The end result of "resistor" experiments carried out on a proper SMPS bulb, the bulb should work (at constant light output), over a range, and promptly switch off (at around half-voltage or so, as an arbitrary design choice). Experiments carried out by hobbyists, should leave them scratching their heads, but no smoke in the room.
Just design your own lights, if you don't like the commercial ones, then see how good you are. You can get nice array LEDs, an inch in diameter, that run off 40VDC or so, and you can use that as a starting material if you want to light a room with just one bulb. But don't expect your project to be small enough, to fit existing fixturing.
Maybe a dropper bulb, instead of an SMPS bulb, would be a starting material. And preferably not the Dubai bulb, as it has a bit of regulation built in. Just a plain cheap Chinese dropper and do your resistor-style experiments. With enough dropper bulbs (each off a separate resistor), you can light a room. Even if it costs a fortune for a given amount of light. Dropper bulbs are preferred by ham radio operators, as the dropper doesn't generate RF hash like the SMPS does. With enough dropper bulbs, you can just switch some off if you want "less light".
The YouTube videos I linked were ways of controlling the brightness of LED strips which typically worked on 12VDC. They may have been fed from a SMPS, but that was irrelevant.
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