unable to find LEDs Drivers ?!?! - Please help

[Ligivo]

Hi guys,

i have been reading several tutorials, watched hours of DIY LEDs system, and tried to figure out myself how to go about, but one solution brings more questions then answers. Maybe someone can help me with this issue.

All i am trying to di is to power up 3 strips of generic High Power LEDs (each one indipendently) but i am not sure how to proceed. Here are the 3 strips specs:


BLUE: 10 High Power Royal Blue star LEDs, all connected in series, each LED has this specs:
V= 3.0v - 3.4v
A= 700mA
W= 3watts
[EDIT: I found this driver: Mean Well MW 9~48V 700mA 35W AC/DC LED Driver LPC-35-700 TUV Class 2 IP67 UL (from ebay). is this ok, or the fact that it delivers higher power and higher voltage can burn the LEDs?]


WHITE: 6 High Power Cool White (6500k), all connected in series, each LED with this specs:
V= 3.2v - 3.8v
A= 700mA
W= 3watts

PURPLE: 4 High Power 420 Purple LEDs, all connected in series, each this specs:
V= 3.2v - 3.5v
A= 350mA
W= 1watts


3 simple questions:

1. What type of Drivers should I get (v=? w=? A=?)? (I cannot seem to find a driver that fits these LEDs)

2. Should the driver be dimmable or I can just buy any driver and connect it to a LED dimmer?


Jason

 

[jiripolivka]

All depends on what you want. LED drivers only generate a suitable current for a LED to operate and survive a long time.
A standard LED connection is with a series resistor that limits the current from a given voltage power supply.
Instead of this resistor, new drivers use pulse width modulation (PWM) to send shorter pulses of a higher current through the LED. Nobody knows, however, how the pulsed current (sometimes 10 x higher than DC average current) affects LED life. Good estimates promise a long life even with such pulsed overload.
PWM offers to dim LED light by shorter pulses.
Do your own experiments and answer the questions!

 

[Ligivo]

Thanks for your help jiripolivka.

Just a tought: the seller did not mention anythng about the dimming capacity, so if I connect the circuit in this way

LEDs--> Dimmer-->DImmable Driver

is there a chnace I can burn the LEDs or that they will simply not work?

 

[jiripolivka]

With PWM LED drivers you should always check the maximum allowed current through the LED (s). Many drivers use several LEDs in series for a higher voltage (again, check LED specs.). Many drivers allow dimming by variable pulse width.
LEDs can be burnt fast by an overdrive. LEDs with a high power must be cooled like any semiconductor device, and it IS a problem when ambient temperature grows.
Now we are only starting to use LEDs for lighting and many components are needed. Soon the LEDs will be integrated with drivers and sold as complete lamps or lighting blocks.
Fortunately, LEDs are not too expensive, so during design one can allow to destroy some when testing their drivers. For LED strings follow carefully their specifications and use current limiters to save money.