It's about time for my yearly post to this site. This time around I'm looking to DIY some LED's for a small tank. My little girls want her own aquarium and she wants glofish. This isn't my first go-round with LED's or Arduino (Here is a short video of what I've been working on for a slot car drag strip http://youtu.be/KPKZ3NmU4WM
My end goal is
- two sets of LED's: white and Violet
- Fade on\off at various times
- the ability to override the programmed levels
Let me preface the rest of this with: I'm not sure how much I should like out to other websites. So, I'm not going to link to anything. I can provide real links if necessary.
This project is going to spin off into probably three more controllers in the near future, so I'm trying to get the first one right. My thought is to go as far as to design and have PCB's printed making the next ones easier. With that out of the way here are my thoughts and questions:
I can only envision needing 3 channels of LED's, on any of these, so I found the Pro Micro based on the ATmega32U4 chip. This is nearly identical to the Arduino Pro Mini, but it has on-board USB. The way I see it I need 3 PWM outputs, and through the infamous auction site I can get them for less than $10 a piece. Naturally I need some sort of a clock so again a RTC from China.
For LED drivers I'm thinking the Mean Well LDD. They all have the same foot print, so I can use different model to control input voltages and amperage's without changing the underlying PCB. This leads me to my first question. How strict do I need to be in matching the input voltage to the aggregate Vf of the LED's? Are these going to generate heat if I give them too much power?
The final piece of the puzzle is avoiding multiple power supplies. If my research is correct I can use a DC-DC Switching converter, to step down from 24V/36V/48V to 5V for the Arduino and RTC. I have found the Traco Power TEL 3-xx11. Replace the xx with 20, 24, or 48 for the corresponding nominal voltage. These will give me 600 mA at 5v from a range of voltages. Does anyone have experience with these? Will they generate much heat?