Looking at some dodgy dimmable led bulbs from the Far East.
Advert states that they must be used with an "led dimmer". I appreciate that using a conventional dimmer that is "over-rated" in terms of max wattage will lead to very non-linear dimming. Are there specific led dimmers now? What kind would I need for a 4x5W led light fixture?
Tim
An effective LED dimmer requires control over the *current* the light draws so you can't use normal light dimmers. You need a specific dimmer designed for use with LEDs of the relevant voltage for the LED in question. Personally I make my own up out of LM338 voltage regulators wired up in an alternative configuration as current sources. Then I can use a variable resistor in place of the programming resistor to control the brightness of the LEDs. I find it works very well.
are the best/most compatbale I have worked with.
Definitely.
Using a resistor to set the current to an LED is an extremely inefficient way of doing things.
Do try to pay attention and read the post properly before making comments; thank you for your understanding.
They call then trailing edge light dimmers normal ones tend to be rising edge.
I don;t understand how LM338 will work with 240V rated LEDs.
You think an analogue voltage regulator any more efficient? Figures.
Of course. PWM has been the way to alter the level of a high powered LED since day one.
They're absolutely fine for my purposes (relatively low power levels) but for serious work, Adam's suggestion of a switching reg is definitely going to be more efficient.
You know that , I know that, the USPTO has other views...
When was day one , think I missed it.
Tim was asking about domestic LED lighting unless I've misunderstood. Not a couple of panel lamps.
Depends how much V it drops.
NT
Thanks. I shall hunt one down.
Tim
Have you read what the thread is about?
C`mon, its usenet threading and topics are for those forum things....
Be aware with Reverse Phase LED dimmers not to connect them to wound low voltage transformers by accident, the back EMF kills them quick.
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