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CORE - OTHER OPTOCOUPLER


titan
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Hello

I've just build my first Core Module, and i cant find the 6N138, thats why i used an HPCL2231 Optocoupler i still have here at home. it's nearly pin compatible, i just had to do a little modofication.

The Bootstrap Loader is burned, but i cant load an application correctly. While the Programm is loading he still sends "Request for Upload" SyxString (F0 00 00 7E 40 [device-id] 01 F7). I tried to attach a LED to the optocoupler and it works fine.

My midi hardware on PC is OK.

When i try to do the loopback test without PIC, the PC sends Sysex but i receive strange messages back like: note off..etc. Is it because 6N138 is a darlington opt.?

What can i do?

Thanx a lot

Titan

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Hi Titan,

years before I used the CNY17-II which is also an optocoupler without darlington stage. Unfortunately it didn't work with all MIDI interfaces, therefore I switched to 6N138.

Maybe the optocoupler is too slow, or - and this would be good news for you - R6 (1.2k) isn't ideal. Just try different values from 220 Ohm to 10k. If you don't have them in house, consider that resistors can be chained or wired in parallel to vary the resistance.

Best Regards, Thorsten.

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Well, if i completely remove R6 the lopp back test works correctly. When i plug in the 18F it doesnt work correctly. I was thinking that R6  is just a pull up resistor and the value isnt important?!?!(Digital values)

I'm hapy i found a shop where i bought 6N138.

Thank for your support.

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Guest didifeed

the 6n139 also works but i fear if you cant get a 138 you also don't get a 139. but i have a idea. you could order samples at fairchild. they ship very fast. i got mine within 2 or 3 days.

greez

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Guest didifeed

whops...

i'm from austria ...

where are you from? strange that they don't send everywhere ... cause i think even my samples came from china.

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Well, maybe it something about my registration information I gave them...

How many parts can u order?

I am searching for some other optocouplers for another project and can't find them anywhere...

Maybe you could order samples for me?

H11F2 is the P/N...

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  • 2 weeks later...
Guest didifeed

sorry for tha late reply.

i don't believe that this will work because they have stored my adress in their database. i also believe that they will not send me samples anymore this month

try other companies like ti ... i don't know but perhaps they have a equivalent to the 6n138/6n139

just google around a little bit. many big companies are sending samples

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  • 1 year later...

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