<!DOCTYPE HTML><html>
<head>
<meta name="Generator" content="Amazon WorkMail v3.1.2381.0">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>RE: [sdiy] MIDI cable impedance and MIDI In ESD protection?</title>
</head>
<body>
<html><head></head><body><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 <mr@analogue.org><br><strong>Sent:</strong> Thursday, June 27 2024, 4:29 pm<br><strong>To:</strong> grant musictechnologiesgroup.com <grant@musictechnologiesgroup.com><br><strong>Cc:</strong> synth-diy@synth-diy.org <synth-diy@synth-diy.org><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">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 class="msg9136596396036473768"><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>________________________________________________________
This is the Synth-diy mailing list
Submit email to: Synth-diy@synth-diy.org
View archive at: https://synth-diy.org/pipermail/synth-diy/
Check your settings at: https://synth-diy.org/mailman/listinfo/synth-diy
Selling or trading? Use marketplace@synth-diy.org
</pre></blockquote></body></html>
</body>
</html>