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

https://www.ebay.co.uk/ulk/itm/291235710260

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

--
Trolls AND TROLL FEEDERS all go in my kill file

On Thu, 21 Apr 2016 20:25:56 +0000, Tim+ wrote:

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

https://www.ebay.co.uk/ulk/itm/291235710260

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.

"Tim+" wrote in message
...
Looking at some dodgy dimmable led bulbs from the Far East.

https://www.ebay.co.uk/ulk/itm/291235710260

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?



http://www.varilight.co.uk/dimmers/v-pro.html

are the best/most compatbale I have worked with.



--
Adam

ARW wrote:

http://www.varilight.co.uk/dimmers/v-pro.html
are the best/most compatbale I have worked with.

Definitely.

In article ,
Cursitor Doom wrote:
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.

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

--
*Stable Relationships Are For Horses.

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
Cursitor Doom wrote:
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.

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

He isnt suggesting doing that, the variable resistor
sets the current that the LM338 provides to the LEDs.

On Fri, 22 Apr 2016 10:42:27 +0100, Dave Plowman (News) wrote:

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.

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

On Thursday, 21 April 2016 21:57:19 UTC+1, Cursitor Doom wrote:
On Thu, 21 Apr 2016 20:25:56 +0000, Tim+ wrote:

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

https://www.ebay.co.uk/ulk/itm/291235710260

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.

They call then trailing edge light dimmers normal ones tend to be rising edge.

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.

I don;t understand how LM338 will work with 240V rated LEDs.

In article ,
Cursitor Doom wrote:
On Fri, 22 Apr 2016 10:42:27 +0100, Dave Plowman (News) wrote:

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.

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

--
*If you don't like the news, go out and make some.

Dave Plowman London SW
To e-mail, change noise into sound.

On Fri, 22 Apr 2016 13:00:17 +0100, Dave Plowman (News) wrote:

In article ,
Cursitor Doom wrote:
On Fri, 22 Apr 2016 10:42:27 +0100, Dave Plowman (News) wrote:

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.

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

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.

In article ,
Cursitor Doom wrote:
On Fri, 22 Apr 2016 13:00:17 +0100, Dave Plowman (News) wrote:

In article ,
Cursitor Doom wrote:
On Fri, 22 Apr 2016 10:42:27 +0100, Dave Plowman (News) wrote:

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.

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

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.

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

--
*A fool and his money can throw one hell of a party.

Dave Plowman London SW
To e-mail, change noise into sound.

On Friday, 22 April 2016 10:44:16 UTC+1, Dave Plowman (News) wrote:
In article ,
Cursitor Doom wrote:
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.

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

Depends how much V it drops.


NT

ARW wrote:
"Tim+" wrote in message
...
Looking at some dodgy dimmable led bulbs from the Far East.

https://www.ebay.co.uk/ulk/itm/291235710260

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?



http://www.varilight.co.uk/dimmers/v-pro.html

are the best/most compatbale I have worked with.




Thanks. I shall hunt one down.

Tim

--
Trolls AND TROLL FEEDERS all go in my kill file

In article ,
wrote:
On Friday, 22 April 2016 10:44:16 UTC+1, Dave Plowman (News) wrote:
In article ,
Cursitor Doom wrote:
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.

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

Depends how much V it drops.

Have you read what the thread is about?

--
*Velcro - what a rip off!*

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
wrote:
On Friday, 22 April 2016 10:44:16 UTC+1, Dave Plowman (News) wrote:
In article ,
Cursitor Doom wrote:
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.

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

Depends how much V it drops.

Have you read what the thread is about?

You clearly didn’t until your nose was rubbed in your terminal stupidity.

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.





--
*Velcro - what a rip off!*

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Rod Speed wrote:
Using a resistor to set the current to an LED is an extremely
inefficient way of doing things.

Depends how much V it drops.

Have you read what the thread is about?

You clearly didn’t until your nose was rubbed in your terminal
stupidity.

Wodney commenting on yet another thing he knows nothing about. The list is
endless.

--
*Why is the word abbreviation so long? *

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
Rod Speed wrote:
Using a resistor to set the current to an LED is an extremely
inefficient way of doing things.

Depends how much V it drops.

Have you read what the thread is about?

You clearly didn't until your nose was rubbed in your terminal
stupidity.

reams of your desperate attempt at insults any 2 year
old could leave for dead flushed where it belongs

Whoops, nothing left. Wota surprise.