[sdiy] MIDI Optocoupler

[James Patchell]

PC900 is what I use as well...I like it mostly because it is very easy to 
use....

i.e. No Fuss, No Muss...
At 05:25 PM 10/22/2005 +0200, Senso wrote:
>One of the most widely used is the PC900 (400kBit/s). You'll find it in 
>lots and lots of synths and MIDI-interfaces and -processors. They are 
>indeed more than a dime each, but I doubt you will need a couple of dozen 
>in a design.
>And they are cheaper than a TL084 or a CA3080. ;-)
>Personally, I'd rather have two that work than 2 tubes of something that 
>might work.
>
>Senso
>
>>The 4N35 might be a little iffy in a MIDI application. Its a general
>>purpose
>>part more suited to control signals (industrial uses abound...) than
>>communications.
>>Most folks opt for the 6N137 / 138 for higher speed use.
>>
>>Some of them will probably work OK...  Its just not a common choice for
>>MIDI.
>>If they worked well, no one would ever use the more expensive parts :^P
>>
>>H^) harry
>>
>>Tim Parkhurst wrote:
>>
>>>  Hi All, Just came across a whole bunch (like 2000) of a Philips 4N35
>>>  optocoupler. I've seen these listed in some Sound Blaster to MIDI
>>>  schematics, so it looks like they're okay for use in MIDI
>>>  applications. What I'd like to know is, what is really the determining
>>>  characteristic for a MIDI optocoupler? Speed? The 4N35 has a switching
>>>  speed of about 3uS, so (1/.000003)/2 = a maximum switching speed of
>>>  approx. 167kHz right? (divide by 2 because each cycle is two
>>>  transitions, and 1/3uS to get frequency... right?) Anyway, if this is
>>>  correct, then this part should be more than fast enough for MIDI. What
>>>  about current capability? Any other factors to look at when picking an
>>>  optocoupler? By the way, if these things are good for MIDI, I'll sell
>>>  'em real cheap since I have so darn many (something like $2 + shipping
>>>  for a tube of twenty, I have to see how many are in a tube).Tim
>>>  (right?) Servo
>>>  --
>>>  "Imagination is more important than knowledge." - Albert Einstein
>
>
>--
>
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         -Jim
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