Hi.
Id like to do one of these: YouTube video but for a single 10W RGBW led so would need an extra mosfet etc for the White channel, but I cant find specs on what components he used or if anyone has anything similar?
Or could I use 4 of these modules to drive the LED?
First of all you have to find out, in the datasheet, whether your LED can be dimmed at all. Dimmable power LEDs usually have a PWM input for that purpose.
That PC board doesn't look like an LED driver... I don't see a coil or a chip. High-power LED drivers usually are switchmode constant current (or controlled current) designs. (These switchmode circuits always have a coil.)
It can be done with a high-power current limiting resistor (similar to how regular little LEDs are driven) but it's not a good design and it's inefficient with the resistor often dissipating (wasting) more power than the LED is consuming.
Are you sure the RGBW LED has a separate white LED?
"Industry standard" dimmable LED power supplies/drivers are controlled with 0-10V DC or 10V PWM, so you'd need a 10V supply. For manual control (0-10VDC) you can simply use a pot. With the Arduino you'd need a "small" transistor or MOSFET (and the 10V supply) to "boost" the 5V PWM output.
You can also find "hobby" LED drivers that are controllable with 5V, and some of the industrial power supplies/drivers have the 10V supply built-in.
**P.S.**Notice the heatsink in the video... High-power LEDs require a heatsink!
DrDiettrich:
First of all you have to find out, in the datasheet, whether your LED can be dimmed at all. Dimmable power LEDs usually have a PWM input for that purpose.
Pretty sure it does. Would be a bit pointless for an rgbw led to not have dimming capabilities! This is the led I ordered.
DVDdoug:
You can also find "hobby" LED drivers that are controllable with 5V, and some of the industrial power supplies/drivers have the 10V supply built-in.
Would something like this do?
Bassquake:
Would something like this do?
I don't see any current regulation or limitation on this board. Without resistors you may kill your LEDs.
Oops, think I meant to link this one.
NO!!! It's got to be a "constant current" LED driver.
Do you have the voltage & current specs for the LED?* (Power is Voltage x Current, so if it's 10W and about 350mA, it should be about 30V.)
Something like [u]this[/u], but check your voltage & current requirements before you order that one. And, you'll have to supply the voltage. (The voltage into a constant-current driver should be higher than the LED voltage... The driver will adjust the voltage down to get the required current.)
Or, try [u]LEDsupply.com[/u].
* P.S.
It looks like you bought something "cheap" with incomplete specs. 
The boards you linked to are for driving common LED strips (with buildin current limiting resistors).
You must add current limiting resistors to the COBs if you want to use the mosfet drivers you linked to.
A better option (less heat), for COBs, is to use constant current LED drivers (not mosfets).
Leo..