rumpelfilter
Offline
Italy

I decided to keep the YM_MINI, since I remembered that I could build a proper DIN MIDI interface for it. I had tried some time ago but failed due to an old firmware, that would not support the baud rate required by MIDI, but this problem has since been solved.

I don't know how many people here on the forum have the YM_MINI, but I would be making PCBs, if anybody wants to join in, we can probably make them for less.
The whole thing is pretty simple and has a relatively low parts count, I'm attaching a quick screenshot of the PCB (still work in progress)

It's very likely that this circuit will work the same for the ANSI vblank (thanks Bleo for pointing me at it). I'll ask Wil from Stray Technologies about it.

Last edited by rumpelfilter (Feb 1, 2014 7:10 pm)

Jazzmarazz
Offline
Michigan

Did you design he PCBs?  A quick look tells me it can easily be one sided, to save you yet more money.

nordloef
Offline
sweden

Interested!!

Comptroller
Offline
Edinburgh

This is the sort of thing that would make me want to get a YM_MINI! Will be watching with interest.

Fudgers
Offline
Indiana

very very interested!

rumpelfilter
Offline
Italy
Jazzmarazz wrote:

Did you design he PCBs?  A quick look tells me it can easily be one sided, to save you yet more money.

Yep I did it. as I said this is just a first rough version, but I agree, one of the next changes will be making it one sided smile

rumpelfilter
Offline
Italy

new version!
To make the PCB smaller I reverted to have panel mount components for the MIDI and PSU plug. I find those components also better for the case design.
The PCB will probably be one-sided, the second layer trace will be replaced by a jumper of course.
Sould I maybe add a reverse polarity protection diode?

nitro2k01
Offline
Sweeeeeeden

I was bored, so I sat down to try to make the layout smaller. Here's what I came up with. I removed the J2 jumper, added a diode, and also flipped the header to the YM_MINI 180 degrees which made the routing easier. It's now completely single-sided.

With a ground plane:

rumpelfilter
Offline
Italy

Cool, even better! I was getting at that, but since you already did an excellent job, I think we can also go with your version smile
J2 was which one? I see you've also added a reverse polarity protection diode, good!

Hey if anybody wants to make these PCBs, go ahead, I'd certainly buy one and I have a bunch of people interested over at the Mutable Instruments forums. I'll also volunteer for testing, but my time is a bit limited, so if anybody is bored and wants to join in, I think this could be a nice community project!

I think the next steps should be: test the circuit on breadboard to see if everything works, I'd do that now but I need to get some components first. Anybody has all the needed parts and can breadboard it before I do?

edit: of course, if nobody wants to make the PCBs I'll do!

Last edited by rumpelfilter (Feb 2, 2014 3:32 pm)

rumpelfilter
Offline
Italy

I talked to Wil about this circuit and got some new feedback. Actually R1 is not really needed, or better, it might create issues with certain MIDI hardware so it's better left away. We could add a jumper to choose between having R1 or not, or one could decide when building the shield (and in case just solder a jumper cable instead of R1).
Also I need to test some bigger caps, to stabilize current in case of a shaky PSU.

rumpelfilter
Offline
Italy

One note about the ANSI MIDIo, apparently this circuit could work with it, but it depends on several factors, so there is no 100% guarantee it will. If you have one of these, you'll have to test it.

rumpelfilter
Offline
Italy

I’ve breadboarded the MIDI circuit (again) and this time it works like a charm. I’ve increased the PSU caps to 10uF and 100uF as somebody suggested here, also I’ve added a protection diode.
Now on to finish that PCB!

nitro2k01
Offline
Sweeeeeeden

Here are my files:

http://www.gg8.se/temp/ym_mini-midi.zip

rumpelfilter
Offline
Italy

thanks! did you make that in Eagle?

rumpelfilter
Offline
Italy

Good news! I just finished assembling the proto board and it works fine! I'll be back with photos and a downloadable ZIP to make your own PCB for this!

Panda Chan
Offline
Melbourne, Australia

Damn! I'm interested!