[sdiy] MIDI processor - power from midi in?

[Richard Wentk]

At 22:17 20/07/2005, nN AAt     e     e wrote:
>doesn't midi have a +5v signal running through one of the pins? i remember
>some simple midi utilities  [arpeggiator, chord memory, filter... all
>probably pic based] that would run off of the midi line as long as you had
>steady power for it and didn't chain them together... shouldn't any keyboard
>or midi interface be outputting enough to power something?

You're limited to 20mA as a maximum. Pull out anywhere close to that and 
there's a danger of errors.

It's the kind of thing that sort of works reliably some of the time if 
you're lucky. But I wouldn't (e.g.) want to rely on it live.

However - since pins 1 and 3 aren't usually connected you can kludge 
something together where you send power down the spare lines. This will 
work IF you design both ends of the connection, solder together your own 
leads, keep them short-ish, and generally don't use the leads/connections 
for anything else.

Richard