[sdiy] MIDI cable impedance and MIDI In ESD protection?

[Mattias Rickardsson]

Thanks all for the discussion and advice.
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.

/mr

Den ons 26 juni 2024 17:21Roman Sowa via Synth-diy <synth-diy at synth-diy.org>
skrev:

> yes, before the resistor, otherwise it made no sense - LED or resistor
> would go poof before TVS start to conduct
>
> Roman
>
> W dniu 2024-06-26 o 17:00, Ingo Debus via Synth-diy pisze:
> >
> >
> >> Am 26.06.2024 um 15:51 schrieb Roman Sowa via Synth-diy
> >> <synth-diy at synth-diy.org <mailto:synth-diy at synth-diy.org>>:
> >>
> >> Maybe better to use TVS across the LED
> >
> > Hmm, usually there’s already a standard silicon diode (1N914 etc)
> > anti-parallel to the LED, for reverse-voltage protection. Would an
> > additional TVS do any good here? The LED or the silicon diode would
> > conduct at a much lower voltage than the TVS.
> > If there’s a really nasty spike, the 220-ohms-resistor would have to
> > absorb most of its energy, no matter which of the diodes/TVS conduct. Or
> > do you mean to connect the TVS _before_ that resistor?
> >
> > Ingo (remembering endless discussions with colleagues on the use of TVS
> > diodes and varistors…)
> >
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