[sdiy] MIDI optocoupler query

Michael Zacherl sdiy-mz01 at blauwurf.info
Fri Jan 5 22:14:46 CET 2018


I don’t have the current/original MIDI specs at hand, but is this high voltage isolation really needed?
IIRC the idea of the optocoupler is to avoid ground loops.
IMHO an order of magnitude less for the isolation voltage would be way enough.
Then again, a search may be in vain since there’s no product for that specs… hm … 

> On 5 Jan 2018, at 21:28, Richie Burnett <rburnett at richieburnett.co.uk> wrote:
> 
> It's the 5kv creepage distance that makes the package large.
> 
> Sent from my Xperia SP on O2
> 
> ---- Tom Wiltshire wrote ----
> 
>> Hi Tim,
>> 
>> The 6N138 offers 5kV isolation, 300% CNR and 20mA current. Putting those parameters in as minimums (combined with SMD packages) gives this list:
>> 
>> http://uk.farnell.com/webapp/wcs/stores/servlet/Search?catalogId=15001&langId=44&storeId=10151&categoryId=700000021001&pf=113080807,111978345,111978347,111978348,111978349
>> 
>> The HCPL 0700 or 0701 look likely candidates. Indeed, these share a data sheet with the classic 6N138/139 MIDI opts:
>> 
>> http://www.farnell.com/datasheets/1266261.pdf
>> 
>> HTH,
>> Tom
>> 
>> ==================
>>      Electric Druid
>> Synth & Stompbox DIY
>> ==================
>> 
>>> On 5 Jan 2018, at 19:59, Tim Ressel <timr at circuitabbey.com> wrote:
>>> 
>>> Yeah, that "SMT" package is just a DIP with the legs modded for reflowing. I was hoping for a part that is smaller than a dip. 
>>> --tr
>>> 
>>> On 1/5/2018 11:53 AM, Pete Hartman wrote:
>>>> Olivier of Mutable Instruments says he has better success with a 6N137 than a 6N138.
>>>> 
>>>> Turns out the '137 has an SMT version
>>>> 
>>>> https://www.mouser.com/productdetail/lite-on/6n137s?qs=sGAEpiMZZMtd3yBnp8bAgJVeHfvx%252b1RWwJnXPJ0hWKA%3D
>>>> 
>>>> And that was just one of several options.
>>>> 
>>>> Pete
>>>> 
>>>> On Fri, Jan 5, 2018 at 1:37 PM, Tim Ressel <timr at circuitabbey.com> wrote:
>>>> Thanks but this is a production design and can't use obsolete parts.
>>>> 
>>>> --tr
>>>> 
>>>> On 1/5/2018 11:35 AM, Jean-Pierre Desrochers wrote:
>>>> Best is Sharp PC900 SMT:
>>>> Obsolete but still available through eBay
>>>> https://www.ebay.com/itm/20-PIECE-LOT-PC900V0YSZX-SHARP-OPTOISO-5KV-OPEN-COL
>>>> LECTOR-6DIP-/302575333531?roken=cUgayN&soutkn=9QY7wa
>>>> 
>>>> JP
>>>> 
>>>> -----Message d'origine-----
>>>> De : Synth-diy [mailto:synth-diy-bounces at synth-diy.org] De la part de Tim
>>>> Ressel
>>>> Envoyé : 5 janvier 2018 13:55
>>>> À : SYNTH DIY
>>>> Objet : [sdiy] MIDI optocoupler query
>>>> 
>>>> Hi,
>>>> 
>>>> Is there a small SMT opto that is known to work as a MIDI receiver? The
>>>> 6N138 is on the portly side and I am out of room on my board.
>>>> 
>>>> Thanks!
>>>> 





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