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jmph

MIDI circuit question

5 posts in this topic

Sorry if this is kind of basic, but I can't figure this out:

midiadap.gif

(Schematic from here.)

Why are there two inverters in immediate succession on the MIDI out line? Doesn't that just reset the signal to its original value? Would there be any consequences (aside from being 'not in spec') if I left them out and just connected the pin directly to R3?

I only want to make a quick & dirty MIDI OUT cable, I'm not concerned with the IN side of the circuit.

Jay

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The double inverters amplify the signal, so it can carry some current.

You can try if your soundcard can do without, but I'd try this with a cheap one first.

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The inverters buffer the signal, decoupling it from the sound card. Not having them may be a bad idea, if some hardware that you attach to it decides to pull a lot of current.

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Thanks for the input guys! I salvaged a 7406N (from a Commodore 64!) and decided to build it "properly".

Repurposed a DB15-RJ45 network transceiver that I found in the trash. Worked perfectly! Might try to add MIDI IN in the future but there isn't a whole lot of room in there...

Some pics of my handywork:

midi-interface-1.jpg

midi-interface-4.jpg

midi-interface-3.jpg

midi-interface-5.jpg

midi-interface-6.jpg

Note the "incorrect" DIN-7 jack, from the same C-64 motherboard. Accepts a DIN-5 fine though. Total cost was $0 because everything was either salvaged or in my parts bin already.

My MB-6582 PCBs arrived last week, I should really start on that next...

Edited by jmph

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"Proper" ftw :-)

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