[sdiy] MIDI phantom power...over 5 pin MIDI connector ?

[Ove Ridé]

On 10 September 2015 at 09:40,  <eidorian at aladan.net <javascript:;>> wrote:
> I just re-read the original post, and it might be that JP isn't asking how
> he can get power from a MIDI cable, he might actually be asking a subtly
> different question: how can he *send* more power over the two MIDI pins
> (presumably without affecting the ability of those pins to transmit MIDI
to
> older devices at the same time).

The MIDI-DIN states that pin 2 should be connected, if nothing else,
through the shield. Are there really cables around that have pin 2
completely unconnected?

> But yeah, there's no fun to be had doing this.  Any device that requires
> your "high powered" MIDI-out ports for power is going to damage your
> "normal" gear if you ever plug it in accidentally :-(

I don't see how. A compliant, regular output device should have 220 ohm
resistors in series on both pin 4 and 5 to limit the current and should
handle even being indefinitely shorted. Likewise, a regular input device
will have 220 ohm in series with the optocoupler. 5/220=23 mA and that's
being really pessimistic and ignoring the LED forward voltage drop.

--
/Ove

Blog: <http://blog.gg8.se/>

"Here is Evergreen City. Evergreen is the color of green forever."


-- 
/Ove

Blog: <http://blog.gg8.se/>

"Here is Evergreen City. Evergreen is the color of green forever."
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