<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">https://midi.org/innovation-award/psimidi</a><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Jun 27, 2024 at 7:54 AM Martin Klang via Synth-diy <<a href="mailto:synth-diy@synth-diy.org">synth-diy@synth-diy.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><u></u>
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<div><p style="margin:0px;font-family:Arial,Tahoma,Helvetica,sans-serif;font-size:small">Well the input, if MIDI compliant, is protected by an optocoupler. Shouldn't that be enough?</p><p style="margin:0px;font-family:Arial,Tahoma,Helvetica,sans-serif;font-size:small">I've seen plenty of DIY and not-so DIY circuits where the output comes straight off an MCU pin, which makes it susceptible to over-voltage and current. I'd put a transistor in line at least.</p><p style="margin:0px;font-family:Arial,Tahoma,Helvetica,sans-serif;font-size:small"> </p><p style="margin:0px;font-family:Arial,Tahoma,Helvetica,sans-serif;font-size:small">Martin</p><p style="margin:0px;font-family:Arial,Tahoma,Helvetica,sans-serif;font-size:small"> </p><blockquote style="border-left:2px solid rgb(176,176,183);margin-left:5px;margin-right:0px;padding-left:5px">-----Original message-----<br><strong>From:</strong> Mattias Rickardsson <<a href="mailto:mr@analogue.org" target="_blank">mr@analogue.org</a>><br><strong>Sent:</strong> Thursday, June 27 2024, 4:29 pm<br><strong>To:</strong> grant <a href="http://musictechnologiesgroup.com" target="_blank">musictechnologiesgroup.com</a> <<a href="mailto:grant@musictechnologiesgroup.com" target="_blank">grant@musictechnologiesgroup.com</a>><br><strong>Cc:</strong> <a href="mailto:synth-diy@synth-diy.org" target="_blank">synth-diy@synth-diy.org</a> <<a href="mailto:synth-diy@synth-diy.org" target="_blank">synth-diy@synth-diy.org</a>><br><strong>Subject:</strong> Re: [sdiy] MIDI cable impedance and MIDI In ESD protection?<br> <div dir="ltr"><div dir="ltr"><<a title="This external link opens in a new window" href="mailto:grant@musictechnologiesgroup.com" target="_blank">grant@musictechnologiesgroup.com</a>> wrote:</div><div class="gmail_quote"><blockquote style="border-left:1px solid rgb(204,204,204);margin:0px 0px 0px 0.8ex;padding-left:1ex" class="gmail_quote"><div><div><div>The latest MIDI electrical spec CA33 shows "optional ferrite beads to improve EMI/EMC <span>performance (FBx </span><span>1K @100MHz)"as well as "optional small </span>capacitor (0.1 μF typical) to <span>improve RF grounding", along with diagrams.</span></div></div></div></blockquote><div> </div><div>And I realize that the TRS MIDI spec (RP-054 from 2017-18) writes an unspecific answer to my other question:</div><div> </div><div>"Because TRS connectors are often used for other (non-MIDI) purposes, manufacturers are strongly advised to add protection circuitry (e.g. to handle the case when a DC-coupled headphone driver is connected to a MIDI output)."</div><div> </div><div>In the world of massive Eurorack systems and tiny plastic synths I expect that pretty loud signals are sometimes connected to MIDI Ins & Outs when confusing TRS MIDI with audio cables. But I wonder what the MMA would suggest that this protection is made, not only in the output case that they mention as example. :-) </div><div> </div><div>/mr</div></div></div><pre>________________________________________________________
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</blockquote></div><br clear="all"><div><br></div><span class="gmail_signature_prefix">-- </span><br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div>Andrei Kudryavtsev,</div><div>Deftaudio <a href="http://www.deftaudio.com" target="_blank">www.deftaudio.com</a><br></div><div>Manufacturing <a href="https://www.instagram.com/luma1_drum_machine" target="_blank">Luma-1 Drum Machine </a></div><div><br></div><div>My last album <b>Two Match - The 1st Fill</b><span style="font-size:12.8px"> on </span><a href="http://itunes.apple.com/us/album/the-1st-fill/id1241529125" style="font-size:12.8px" target="_blank">iTunes</a><span style="font-size:12.8px"> </span>and <a href="https://open.spotify.com/album/4aM8DzmN5yi4ho1gcmC8ls" target="_blank">Spotify</a></div><div>Follow me on <a href="https://www.facebook.com/andrei.kudryavtsev.5" target="_blank">Facebook</a>, <a href="https://www.instagram.com/deftaudio/" target="_blank">Instagram</a></div></div></div></div></div>