If I wanted to get one of your PCBs, where could I find one? 8 of those is about right for the tank I'm building.
Foxy,
I just ordered 10 PCBs for CAT 4101 and I need only 4. Stay tuned and PM your email address.
cheers,
MaLi
If I wanted to get one of your PCBs, where could I find one? 8 of those is about right for the tank I'm building.
Foxy, the CAT4101 essentially fills the same purpose as you are proposing the LM317 for - they're both linear regs that can be run in constant current mode. The big differences are that the CAT4101 is made to accept a separate PWM control signal, so you don't have to PWM the power line yourself (which is probably not as simple as it looks if you want good control) and, even more importantly, the CAT4101 has a .5v minimum dropout, while the LM317 is something like 2.5v. This means it'll run more efficiently, and it'll be easier to run it "hard" (near it's current limit) without needing heatsinking. An LM317 run anywhere near it's 1.5A current limit needs a HUGE heatsink PLUS active cooling PLUS careful PCB design PLUS an ideal environment. A CAT4101 run at 1A only needs heatsinks or active cooling if your PCB sucks or you're running in a bad environment.
Now, because lower drop-out if you trim the output voltage of your supply lower, then you CAN decrease dissipation of the chip.... just to be clear to those trying this.
I asked this question to myself in this thread: http://www.reefcentral.com/forums/showthread.php?t=1953353Are there any drivers that can run a string of 25 or more leds at 750mah?
I think that you can use a splash screen and place the fixture 2" above water. In this case optics won't be necessary for sure.a maximum height of about 10 inches above the water. Since the fixture will to so close to the water
I would almost always recommend optics, regardless of fixture height, especially when using the XP-series LEDs.
Optics will greatly improve the efficiency of the fixture by grabbing all of the light that's shining off to the sides, and the light that's hitting the water at too much of an angle to penetrate significantly, and will help to channel it down into the water.
Even if you don't feel like you need them due to the shallowness of your tank or fixture height etc, use them anyway and then you get to run your LEDs at a lower drive current and save more on the power bill etc.
The only situations where I would be hesitant to recommend optics, or would say really wide optics only are when either all of the LEDs are grouped into a very small cluster or when there is a lot of space between each LED.