[sdiy] Optocouplers and MIDI

[aankrom]

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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