[sdiy] Optocouplers and MIDI

[Ian Smith]

Yeah, I noticed the pin difference. I don't really plan on doing anything too fast with it. Well, I guess there's only whipping up a circuit and trying it out.

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> Date: Sun, 18 Sep 2011 13:40:47 -0400
> From: aankrom at bluemarble.net
> To: synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] Optocouplers and MIDI
>
> Well it's not a drop-in replacement because the 4N29 is a 6-pin DIP and
> the 6N138 is an 8-pin DIP. The 4N29 is about ten times slower as well.
> I'm not sure how critical this is for MIDI, since MIDI is a pretty slow
> protocol. Current handling capability is about the same. I'm guessing
> the 6N138 is faster because it uses a photodiode to switch the
> Darlington pair. The 4N29 is also a Darlington, so it's not like you're
> trying to use a triac optocoupler, which would NOT work in a MIDI app.
>
> I wondered the same thing about the handfull of H11N3's that I have:
> they're Schmitt triggers with open-collector outputs. Kinda cool, but
> probably not the best bet for MIDI.
>
> I think the only issue with the 4N29 might be speed.
>
> AA
>
> On Sun, 18 Sep 2011 10:55:54 -0500, Ian Smith wrote:
> > Hey all,
> > Going through my box of bits, I found a couple 4N29 optocouplers and
> > was wondering if they could be used in place of the usual 6N138s
> > normally found in MIDI to CV circuits.
> > -Ian
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