[sdiy] Detecting the presence of a receiving MIDI device through current sensing

[Brian Willoughby]

On Jan 27, 2020, at 8:25 PM, MTG <grant at musictechnologiesgroup.com> wrote:
> I like the last bit, the sensing. Certainly there will be current flow and voltage drop if anyone is attached.  The bit at the beginning about "constant" current flow ... seems to me you'd be adding edges from the circuit that is active while the MIDI one is not, so that introduces it's own issues. But it's all quite clever. I like it.

I’m not following.

Keep in mind that MIDI is a current loop, so both the MIDI circuit and the other one will be dumping current to ground on the sending side. If the alternate circuit’s path is close to the MIDI jack, or at least close to the hex inverter that drives the MIDI output, then there’d be a constant current being dumped into ground there.

Brian