I'm starting on my first AVR project outside of my STK500 and am trying to figure out how to power it. I spent some time searching the forums and couldn't find an answer, but if I've overlooked something please share the link!
I am powering an LED lighting effect system. Essentially it's a string of LEDs in serial and parallel, requiring 18VDC. This will be controlled through a TIP41 on a GPIO of an AVR. Since the AVR is powered by 5VDC, the question is, "What is the best way to get both 18V and 5V?"
I've got an 18VDC power supply (mains-powered) and was thinking of just connecting a 7805 to it, but that's 13W if I'm calculating it correctly, which seems a bit high. 5V current draw should be pretty low but the 18V side will be a couple amps due to the LEDs.
Keeping things relatively simple (i.e., few components) is desirable (but not required) since this is my first 'big' electronics project.
I also considered using both the 18V power supply ('wall-wart') as well as a 5V supply, with the negative side of each tied together, though I was concerned that they may not be at the same potential, resulting in high current (and damage) between the supplies.
Any advice/direction is appreciated!
Related: I've blown up a couple 7805s hooking it directly to the 18VDC with no diode or load. I'm not certain why that's happening but I'm currently reading through The Power Supply page, linked from the sticky thread, and I think that'll tell me what I need to do.