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<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>
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<div><span>GB</span></div>
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<div>------ Original Message ------</div>
<div>From "Mattias Rickardsson" <<a href="mailto:mr@analogue.org">mr@analogue.org</a>></div>
<div>To "<a href="mailto:modular@go2.pl">modular@go2.pl</a>" <<a href="mailto:modular@go2.pl">modular@go2.pl</a>></div>
<div>Cc "<a href="mailto:synth-diy@synth-diy.org">synth-diy@synth-diy.org</a>" <<a href="mailto:synth-diy@synth-diy.org">synth-diy@synth-diy.org</a>></div>
<div>Date 6/26/2024 1:57:09 PM</div>
<div>Subject Re: [sdiy] MIDI cable impedance and MIDI In ESD protection?</div>
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<div id="xc5a7a7638ecc413">
<blockquote cite="CAP92RBUi4RwGgrHoVun772UfERZzXps5o2mQBBCfQ6jYjV4QKA@mail.gmail.com" type="cite" class="cite2">
<p dir="ltr">Thanks all for the discussion and advice.<br>
Also a good idea to peek in commercial schematics, I see Kurzweil's 1nF caps now. :-) A bit larger than the 330pF ESD caps I was simulating, and a bit smaller than the 3nF of the wurst-case MIDI cable in Roman's example - which barely passes the MIDI pulses
with style.</p>
<p dir="ltr">/mr</p>
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<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">Den ons 26 juni 2024 17:21Roman Sowa via Synth-diy <<a href="mailto:synth-diy@synth-diy.org">synth-diy@synth-diy.org</a>> skrev:<br>
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<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
yes, before the resistor, otherwise it made no sense - LED or resistor <br>
would go poof before TVS start to conduct<br>
<br>
Roman<br>
<br>
W dniu 2024-06-26 o 17:00, Ingo Debus via Synth-diy pisze:<br>
> <br>
> <br>
>> Am 26.06.2024 um 15:51 schrieb Roman Sowa via Synth-diy <br>
>> <<a href="mailto:synth-diy@synth-diy.org" rel="noreferrer">synth-diy@synth-diy.org</a> <mailto:<a href="mailto:synth-diy@synth-diy.org" rel="noreferrer">synth-diy@synth-diy.org</a>>>:<br>
>><br>
>> Maybe better to use TVS across the LED<br>
> <br>
> Hmm, usually there’s already a standard silicon diode (1N914 etc) <br>
> anti-parallel to the LED, for reverse-voltage protection. Would an <br>
> additional TVS do any good here? The LED or the silicon diode would <br>
> conduct at a much lower voltage than the TVS.<br>
> If there’s a really nasty spike, the 220-ohms-resistor would have to <br>
> absorb most of its energy, no matter which of the diodes/TVS conduct. Or <br>
> do you mean to connect the TVS _before_ that resistor?<br>
> <br>
> Ingo (remembering endless discussions with colleagues on the use of TVS <br>
> diodes and varistors…)<br>
> <br>
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