Very high powered LED's dimming - n00b

[kokofi3]

So I'm getting in some new LED's, they are reported as 20 Watt RGB LED's.
DC Forward Voltage (VF): Red 13-15V, Green 18-20V, Blue 18-20V
DC Forward current (IF): 600MA
I am new to most electronics with a very minor background.
Originally I was looking at putting pots on them (then realized they won't hold that much)
then looking at dimmers from home depot (treating the LED's like bulbs in a house, but that's 120 v
next looking at transistors, but not sure what I would be looking for. I think one of 15v for red and two for 20v for b/g and have them rated for 0.6 A.
then someone told me to look at mosfets, but if I'm not mistaken those are on or off, (dimming is a must)

so with all this cluster of n00bism, I'm turning to the internet for help!

[fungus]

So I'm getting in some new LED's, they are reported as 20 Watt RGB LED's.

Need info on the LEDs.

[Grumpy_Mike]

First you need to know the current theses LEDs take. The voltage you quote is not the voltage for a single LED so you must have a cluster of some sort.
What you need is a constant current power supply at the current the LEDs need. They you apply pulse width modulation to get the dimming, but yes we need to know a lot more about the lights. A link to them would be good.

[kokofi3]

Here's a link to the LED's :
http://www.ebay.com/itm/251348336578?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

I contacted the seller and am asking for the spec sheet.

[fungus]

Did you get any heat sinks for them?

[Grumpy_Mike]

You need to look for a 600mA constant current LED driver. While there are a lot of them about you need to make sure you have one with a PWM input, so many do not have this feature.

Yes you will need a big heatsink on each of these LEDs.

[kokofi3]

I was thinking about soda cans, but that seems like not enough, maybe an old computer heatsink with a fan and all.

[Grumpy_Mike]

I was thinking about soda cans, but that seems like not enough,

By far the most important parameter in a heat sink is surface area, so that might be good enough.
A good heat sink thermal compound between the component and heat sink makes a lot of difference.

[Headroom]

What you needn't addition to the LED(s) if you are going for a DIY product are four main components:

Power supply
Heatsink - available at eBay as well
Microcontroller - Arduino or compatible too  control PWM for dimming.
Constant  Current LED driver

There are heaps of el-cheapo Chinese products available on eBay with no documentation, total lack of competent or any customer support. There are several constant current drivers available on Tindie.com and also a few  Arduino shields Tindie.com that can be stacked directly onto an Arduino. Which one you use depends on your specific application.

[Paul__B]

I was thinking about soda cans, but that seems like not enough, maybe an old computer heatsink with a fan and all.

Two questions about aluminium cans - how durable are they, and the problem that the material is too thin of itself to be readily clamped to the heatsink of the device.  It is do-able; you generally would need a sturdier piece of aluminium on the other side of the can material to hold that flat against the device heatsink when you bolt it down.

A computer heatsink with fan would do fine.  Again, you need to arrange clamping to ensure complete contact.  Some LED assemblies now do include a fan-forced heatsink.

[Grumpy_Mike]

the problem that the material is too thin of itself to be readily clamped to the heatsink of the device.

No this is just simply wrong, from both a mechanical and thermal viewpoint.
The thickness does not matter very much, what maters is if you can get a good thermal contact between the device and the sink. It might be that the curvature of the can prevents this but it is always possible that you can distort the can or use a space filling thermal gel pad.

[kokofi3]

So doing some more research I found these http://www.newark.com/fairchild-semiconductor/pn2222bu/bipolar-transistor-npn-30v/dp/83C0223
Would I be right to assume that emmiter break voltage is the minimum voltage required for power to flow?
So would these be the transistors I have been looking for?

[Grumpy_Mike]

Would I be right to assume that emmiter break voltage is the minimum voltage required for power to flow?

No.
What do you mean by "emitter break voltage", it is not in the data sheet nor the page you posted and I have never heard of the term.

So would these be the transistors I have been looking for?

No.
You want to switch 600mA, that transistor has a maximum rating of 600mA, there is no margin, you need a transistor that can switch at least 800mA.

Even then you no not need a transistor but as I said before a constant current supply.