Question about the Mitch MIDI Switch!

[SpufuZ]

Hello!
Im planning on building this MIDI switch, http://www.jimkim.de/html/guitar01_01.htm, and i have a question!
I want to use two of them in order to get 2x4 relay-switchers but how can i hook the MIDI up since the switch only have MIDI IN?
Do it have to have MIDI Trough or can i just connect both switches to the same jack in parallell and configure each switch with different channels?


//david

[SpufuZ]

No one who has an idea?

[scratch]

no, you can not simply parallel the Jacks ... MIDI is a single current loop driven serial bus, the current has to flow through all of the connected devices.

There are schematics out there for simple 'through' boxes that you would need to connect two of these switch boxes.

for example ... http://m.bareille.free.fr/midithrubox/midithrubox.htm

[SpufuZ]

Ok thanks for your answer!
So this way it wont be any problem controlling several devices on different channels right?

Excuse me for asking dumb questions. 
//david

[scratch]

I'm just going by what I've read in various MIDI articles ...

You could go either way, did not look up t he Mitch unit to see how it operated ... either set them both up to channel 1 but program them differently, or set them up to different channels and program your MIDI transmitter to send the correct messages on the appropriate channel?

[butcher55]

SpufuZ: How did you solve the problem with MIDI Thru port? I'm also planning to build Mitch switcher (most likely 2 of them combined) and I'll also need the thru port.
Question 2: are you going to make separate PCBs, or you'll combine them together? I need some inspiration
thanks in advance

[G. Hoffman]

Now, I'm not 100% here, but I would be willing to bet you could run the output of the optoisolator through a buffer of some sort, and send it to both circuits. It would be worth bread-boarding, at the least.


Gabriel

[butcher55]

Please excuse my lame questions, I'm just a poor beginner - is it possible to use 16f84A chip instead of 16f84 in this project? Or it requires changes in the code?

[G. Hoffman]

Please excuse my lame questions, I'm just a poor beginner - is it possible to use 16f84A chip instead of 16f84 in this project? Or it requires changes in the code?

I've done it.  The only thing I needed to do is tell MPlab that I was using a 16F84A instead of a 16F84.  I haven't built a complete box yet, but I have bread boarded it and it worked fine.  I also used a 16F84A for his MIDI switcher, which IS a finished project.  (I tried both a 16F84, and a 16F84A on both projects.)


Gabriel

[butcher55]

Thanks much
Do you have any pics of the progress so far?

[G. Hoffman]

Thanks much
Do you have any pics of the progress so far?

Just of the (mostly) finished switcher.  I still need to go to the scrap yard and find a thin sheet of aluminum I can use to go over the box and cover the holes that were already there (and etch, because I'm finding etching kind of fun right now).  (The box, by the way, is from Weber, in their "generic enclosures" section.  Not a great box, but the size and price are certainly right!)  

My camera died a few months back, and I haven't been able to replace it yet, so I have to borrow a camera to take pictures.



I set mine up with four of the switches controlling audio loops, and four of them driving a 4016 that switches stuff in my amp and a speaker switch to turn on my Leslie.  Now, as I start trying to put together a pedal board around it, I'm finding I need more loops.  Typical, right?  So, a Mitch is probably in my near future too - I just have to decide on a box for it, and make the circuit board.  (I ended up getting a circuit board made for the brain part of the Switch, and I have two left over if anyone wants one.  I don't know what I would need for them, as it was a small run so they aren't exactly cheap for me; they don't have solder mask or silkscreen either.  I made them for myself, not to sell, you know?  It also doesn't have anything in the circuit after the 74HC573 latches - no 7-segment display decoder, no relays or switches, or anything like that - which makes for a lot more off board connections than I would have liked, but also makes for a large degree of versatility, in that you can use relays, logic switches, or really whatever you want that won't overload the latches).

Oh, hey, and I DO have a picture of the three boards for the MIDI switcher!  I forgot I had these.



I needed the double sided board for the "brain" part because to do it one sided would have taken up even more room, and would have required something like 20 jumpers .  At that point, I think you should just buy the thing.  (It was the buses from the 16F84A to the 74HC573s that were such a hassle - I tried, believe me I tried, but a single sided board just wasn't going to happy with my skill level.  Though I think the trying raised my skill level about 200%.)  I can, however, report that the board works!  Well, I had to ditch two diodes from the 5V regulator circuit, but they were optional anyway.


Gabriel

[karol3188]

How you made square hole for led display?
thanks

[G. Hoffman]

I drilled out most of the material, roughed it out with a coping saw, and fit it with a file.  Not the best way to do it, but it worked.  Also, about the extent of my metal working capabilities - I'm a woodworker by trade, but this thing is a steel enclosure. 


Gabriel