Mios Audio Router / Footboard update.

[msi]

I've designed a audio router to integrate into the dout modual.  I'm looking for someone to take a look and see if I've messed anything up.  As far as I can tell, it should work.  The link is here, http://216.250.178.122/will/midibox/signalrouter/signalrouter.gif 

The interface is pretty simple. For my needs, I've set up three parrallel loops, and three series loops.  The three parallel would be for my rack preamps, and the series loops for rack effects.    There will be six buttons to either open or close the relay, and six LED's to indicate if its open or not.  There will be two additional buttons to control patch change up, and down.  Pressing both will enable the write function to save the settings for that patch.  Finally a seven segment led will indicate which program its currently on.  This should only need One core, a Dout, and a din.  Does that sound proper?

The other thing I'd like to do is a new footpedal design.  For this I've got planned four channel buttons, a, b, c, and d.  And a bank up and down buttons that go from bank 1-16.  Thus programs 1-128 can be achieved.  This works well for how I play anyways, because I generally only use three or four sounds per song anyways.  This will have a graphical display so I can name the patches.  Finally, a write button and a shift button for more advanced features.  The reason for the shift button is to allow me to assing diffrent program changes to diffrent midi channels.  So I can have say preamp 1 on program 4, and preamp 2 on program 43.  I don't know if I will need this, but at least it will be there.  Finally, I'm thinking of have two Ain's for expression controll.  Again, that can be assigned to diffrent continuous controllers using the shift button.  This should only require a Core, Din, LCD modual, and if I go with the expression controllers an Ain as well. 

Does that all sound kosher to everyone?

[d2k]

Nice idea :)

I think the schem is coo, perhaps some general NPNs (emitter to gnd, collector to relay coil) with 1K resistors on the base added on the 595 outputs tho?

[msi]

Yea, it was my understanding that the ULN2003 would negate the need for individual transistors on each output pin of the 595.  Or would individual transistors be a better route to go with?

[smashtv]

Yea, it was my understanding that the ULN2003 would negate the need for individual transistors on each output pin of the 595.  Or would individual transistors be a better route to go with?

I like the individual transistor method myself, but it's your box and both ways work fine.

You might be able to lose the relay coil diodes also with the ULN....with some of the ULN drivers these diodes are not needed.

best!

Smash

[d2k]

oops ye i forgot the ULN chips has it all in there already - just use to seeing resistors there!

[LiFo]

what about clicks from the relays

have you thought about that

i am about to do a somwhat similar design and was looking for another solution than relay's

and have found an “Clickless†Bilateral Audio Switching SSM2402 but it is realy expensive

[d2k]

i think if you keep the ground return path of the relays sep from the analog ya should be cool no?

[msi]

Yea, to prevent popping from the relays, I plan to have a fet attached to one of the pin's of the dout.  When the core switches a relay, it will also activate the fet to shunt the signal to ground.  This is the methode used in production amps.  The other method would be a optoisolater/led combination in the same spot as I'd put the fet.  The relay side of things is pretty sketchy right now.  I'm thinking I'll use a buffer at the front, and a passive EQ at the output.  I plan to keep the analog/digital grounds seperate. 

[SexyBeast]

Hi,

i found this Maxim chip MAX4562, which is a multiple analog switch with an i2c control. It is made for applications like yours and you could save the DOUT and the relais control using them.

Datasheet:    http://pdfserv.maxim-ic.com/en/ds/MAX4562-MAX4563.pdf

The drawbacks are that I can't find a dealer for it (thoug you could order samples...) and that it only comes in a QSOP (SMD) package.

regards, tom

[msi]

I haven't looked at the datasheet yet, (it's loading right now) but the thing I like about relays is I can keep the audio ground, and the digital ground seperate.  But I'll check out the datasheet.