Led downlighters flickering

[assegayer]

Something like this wouldnt work right as its constant voltage and not constant current

POWERPAX - PLV2524-01 - 24Vdc, 250mA, 6W Constant Voltage Miniature LED Driver | CPC UK - http://cpc.farnell.com/powerpax/plv2524-01/24v-dc-250ma-led-driver-lugs/dp/PW02617?ost=250ma+driver&selectedCategoryId=&searchView=table&iscrfnonsku=false

 

[Richard Burns]

The one from Germany may well work it has the 250mA output however it is only a maximum of 8W whereas your original is 11W, so long as you do not need more than 8W this is OK.
The constant 24V one would not be a good choice but may work, since if you look at your existing driver the minimum voltage is 23V (max 38V) and so if the lamps were fed 24V it is unlikely the current would be too much, however there would be no control of the current and if you wanted a 9W supply then the driver would be overloaded as it is only 6W.

Now I have actually looked the 250mA ones are not common, most start at 350mA.


Lamps that require constant current should have printed on them a wattage and current rating and not give a voltage rating.
If they need constant voltage then they will have a wattage and a voltage rating normally for individual lamps this is 12V, LED strips can be 12,24,36,48 V
Generally LEDs are wired in series for constant current and in parallel for constant voltage.

Mostly assemblies of LEDs might be constant current but individual items are constant voltage. It is much easier to get a 12V driver for LEDs and make sure it can take the total wattage which is what you would normally have for LED lamps on their own.
You have the slightly more complex arrangement of a set of lamps.
However usually they would be 350mA for which there are hundred of suitable drivers out there.

For your application I am assuming this is a set of MR11 LEDs in a unit or something like that, otherwise I would expect them to be 12V items even for MR11.

MR11 is not GU10
This is a diagram of some lamp bases for comparison.

 

[assegayer]

The one from Germany may well work it has the 250mA output however it is only a maximum of 8W whereas your original is 11W, so long as you do not need more than 8W this is OK.
The constant 24V one would not be a good choice but may work, since if you look at your existing driver the minimum voltage is 23V (max 38V) and so if the lamps were fed 24V it is unlikely the current would be too much, however there would be no control of the current and if you wanted a 9W supply then the driver would be overloaded as it is only 6W.

Now I have actually looked the 250mA ones are not common, most start at 350mA.


Lamps that require constant current should have printed on them a wattage and current rating and not give a voltage rating.
If they need constant voltage then they will have a wattage and a voltage rating normally for individual lamps this is 12V, LED strips can be 12,24,36,48 V
Generally LEDs are wired in series for constant current and in parallel for constant voltage.

Mostly assemblies of LEDs might be constant current but individual items are constant voltage. It is much easier to get a 12V driver for LEDs and make sure it can take the total wattage which is what you would normally have for LED lamps on their own.
You have the slightly more complex arrangement of a set of lamps.
However usually they would be 350mA for which there are hundred of suitable drivers out there.

For your application I am assuming this is a set of MR11 LEDs in a unit or something like that, otherwise I would expect them to be 12V items even for MR11.

MR11 is not GU10
This is a diagram of some lamp bases for comparison.
View attachment 33868

I really do appreciate your time you take take to do these indepth explanations. so If i understand correctly in theory i could change a bulb to voltage constant one and then fit a voltage constant trannie as all of the leds have there own individual driver? All in theory off course.

 

[Richard Burns]

yes that would be fine.
The constant current driver is now a bit odd if they have individual drivers, most MR11 lamps on their own would be 12V, but do check the lamps just in case.
If the lamps say 12V on them then the wrong driver was used originally.

 

[assegayer]

So constant current drivers are only used for multilple leds?

 

[Richard Burns]

An LED lamp such as a GU10, MR16, MR 11 has multiple LED chips in it (in many cases) so presumably could be built to use a CC driver, however constant voltage drivers are cheaper to make so they design for those.

Where there may be a variable number of LEDs being installed such as in plinth light kits then a constant current driver is more flexible.

An LED as a component without any control circuitry would almost certainly benefit from a constant current source because once they start conducting the internal resistance is very low and so the current would just ramp up until they failed, the usual method of control is to apply a resistor before the LED so that the resistor limits the current drawn.

So in general single lamps are constant voltage, however multiple lamps can be either but often tend to be constant current.

 

[assegayer]

So if i am correct when each lamp is on there own driver its not too important whether cc or cv driver?

They could be wrong from the start, but are they really if each lamp has its own driver.

 

[Richard Burns]

You should use the type of driver specified for the lamp, whatever that is.

If you had a 5W LED lamp that required a constant current of 350mA you should be installing a 14.28V driver based on P/I = V. So fitting a 12V 5W driver would probably work OK but the lamp is not designed for it, however the current would very likely be stable as there is no variance between LEDs as there is only one LED.
Since it should need 350mA and you will probably supply less than 350mA with only 12V it may survive, however if there is no current control in the lamp then the lamp could fail.

 

[assegayer]

You should use the type of driver specified for the lamp, whatever that is.

If you had a 5W LED lamp that required a constant current of 350mA you should be installing a 14.28V driver based on P/I = V. So fitting a 12V 5W driver would probably work OK but the lamp is not designed for it, however the current would very likely be stable as there is no variance between LEDs as there is only one LED.
Since it should need 350mA and you will probably supply less than 350mA with only 12V it may survive, however if there is no current control in the lamp then the lamp could fail.

THANKS!! understand now