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<p>If you have the space and budget, use two optocouplers: one for
each direction, that allows you even to sense which direction it
is. </p>
<p>(So you can change the output too...)</p>
<p><br>
</p>
<p>Where do I collect my prize? :)</p>
<p><br>
</p>
<p>Best,</p>
<p> René</p>
<p><br>
</p>
<div class="moz-cite-prefix">Am 28.06.2024 um 00:06 schrieb Mattias
Rickardsson:<br>
</div>
<blockquote type="cite"
cite="mid:CAP92RBU-GKiWVCA1n81n6NvXV36mk+UQt=WH0Z-Fb2BD3d-RjA@mail.gmail.com">
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<div dir="ltr">On Thu, 27 Jun 2024 at 20:55, Andrei Kudryavtsev
<<a href="mailto:andrei.kudryavtsev@gmail.com"
moz-do-not-send="true" class="moz-txt-link-freetext">andrei.kudryavtsev@gmail.com</a>>
wrote:<br>
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style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div dir="ltr">Speaking of TRS mess, found this one in the
recent application list for MIDI innovations:
<div><a href="https://midi.org/innovation-award/psimidi"
target="_blank" moz-do-not-send="true"
class="moz-txt-link-freetext">https://midi.org/innovation-award/psimidi</a></div>
</div>
</blockquote>
<div><br>
</div>
<div>Oops, that has been solved in commercial products for
over 5 years. </div>
<div>But without those extra diode voltage drops! </div>
<div><br>
</div>
<div>(Assuming 1.9 V drop for the optocoupler and 2 x 0.3 V
drop for the Schottkys, and the new 3.3 V (+/- 5 % on the
lower side) logic level, there's 0.635 V left for the 220
ohm resistor. The current is then only 2.9 mA, far below the
required 5 mA. Oops2!)</div>
<div><br>
</div>
<div>(It would need to have 127 ohms instead of 220. But with
5 V (+/- 10 % on the higher side) logic level, and 1.9 +
0.3 + 0.3 V voltage drops, you get 3 V over the resistor.
23.6 mA is above the specified Abs Max input current of the
6N138 optocoupler suggested in the MIDI spec, even if the
6N137 used here will survive. Oops3!)</div>
<div><br>
</div>
<div>I'm sure similar gender-agnostic TRS MIDI In jack
solutions must have been implemented by several
manufacturers by now? It was a bit weird to see different
brands using different polarities when TRS MIDI emerged, and
even more strange to see MMA omit a solution for it in the
new standard. :-) </div>
<div><br>
</div>
<div>Thanks for the reading tip, Andrei!</div>
<div><br>
</div>
<div>/mr</div>
<div><br>
</div>
<div>PS: I wrote "TS" in my first message, mistake - should
have been "TRS". Sorry.</div>
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