MIDI Out w/ 3.3V board (and related PSU question)

Hey guys, Quick question re: MIDI out from an Arduino, as per:


I'd presume the general solution to doing this with a 3.3V Arduino board would be to use the +3.3V rather than +5? This technically isn't kosher with MIDI spec, which specifies +5, but since it's a current loop and inputs are opto-isolated, should be ok, right?

A quasi-related question, f I wanted to, could I connect to Vcc rather than +3.3V for pin 4 of the DIN?

My problem is that I'm trying to power the Arduino off the +5V from a MIDI device connected to the Arduino's input, but many MIDI device manufacturers don't actually observe the spec, and some run as low as 3.3, while others can (although rarely, I've never seen it, only heard rumor) be as high as 12V. So I'm trying to figure out the best way to cope with this. Connecting to Vcc would at least solve my problem, albeit I'd be passing the buck on the output side of life to whatever voltage the device I'm connected to is providing, which I don't love, but could deal with.

Otherwise, I need to start investigating a power supply circuit that I can use with a 5V Arduino that will either step up a 3.3V to 5V, or regulate something as high as 12V down to 5V. Or, I suppose, a step up to 7V, and that is happy passing 12V as whatever it comes out as, and then feeding that to the Arduino's regulator?

Thanks, Andy