Arduino based Input Selector for preamp

[_atari_]

Over at head-fi I am developing a complete microcontroller based pre amp. The first step is the balanced input selector.
I repost this here to also ask you for help & recommendations:

Thanks to the encouraging help of linuxworks I was able to design the first complete microcontroller oriented input selector:


This board is intended as an extension for linuxwork's LCDuino.

The features:

• I2C based control via MCP23008
• all inputs are switched by relays
• all inputs can be either single ended or balanced (singe ended to balanced conversion will come as a different board)
• several board can be combined to get more inputs

What changed regarding to the prototype:

• usage of non latching relays (easier to source)
• filter selection is gone (will be a different board)

A first draft of the board is also available. No PCB traces drawn until now. Check the thin yellow lines what goes where (click for high res versions)



The analog section is on the top part of the board. With some nice ground plane on top and bottom of the board.
The digital section is completely on the bottom part of the board. Ground plane on bottom, VCC plane on top.

What do you think?
Is there anything I have done wrong or I can do better?
What do you think?

[maxw]

Did you finish this? Any chance I could see the code? I'm making the same thing but also a relay based volume controll. Cheers

[Dougie085]

The δ2 relay-based input/output selector


Not sure if it's the same? Doesn't look like that one can be configured as balanced/SE. I'd love to be able to use one of these and have balanced connections and have it setup with the preamp I want to build.

[maxw]

Originally Posted by Dougie085

The δ2 relay-based input/output selector


Not sure if it's the same? Doesn't look like that one can be configured as balanced/SE. I'd love to be able to use one of these and have balanced connections and have it setup with the preamp I want to build.

If you want balanced can't you just use two boards?

[Dougie085]

I'm not sure how that would work for an input selection board?

[maxw]

Originally Posted by Dougie085

I'm not sure how that would work for an input selection board?

One board is for your balanced left channel, and one board is for the balanced right channel. I've never used balanced equipment but pretty sure this works.