Led dimmer?

Looking at some dodgy dimmable led bulbs from the Far East.

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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

Reply to
Tim+
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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.

Reply to
Cursitor Doom

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are the best/most compatbale I have worked with.

Reply to
ARW

Definitely.

Reply to
Andy Burns

Using a resistor to set the current to an LED is an extremely inefficient way of doing things.

Reply to
Dave Plowman (News)

Do try to pay attention and read the post properly before making comments; thank you for your understanding.

Reply to
Cursitor Doom
338 tends to get a bit hot, modern switch mode current drivers are available as modules that run a lot cooler :-)
Reply to
Adam Aglionby

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.

Reply to
whisky-dave

You think an analogue voltage regulator any more efficient? Figures.

Reply to
Dave Plowman (News)

Of course. PWM has been the way to alter the level of a high powered LED since day one.

Reply to
Dave Plowman (News)

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.

Reply to
Cursitor Doom

You know that , I know that, the USPTO has other views...

Reply to
Adam Aglionby

When was day one , think I missed it.

Reply to
whisky-dave

Tim was asking about domestic LED lighting unless I've misunderstood. Not a couple of panel lamps.

Reply to
Dave Plowman (News)

Depends how much V it drops.

NT

Reply to
tabbypurr

Thanks. I shall hunt one down.

Tim

Reply to
Tim+

Have you read what the thread is about?

Reply to
Dave Plowman (News)

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.

Reply to
Adam Aglionby

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