Relays - Audio and Digital Ground.

[lukatosh]

Hi everyone, my name is Lucas and I'm Writing from Chile!

Hope you can help me clarifying some concerns about bypass using relays. Hope you can understand my google english...

i've been making a relay based looper using arduino and since Chile is an electronically isolated island      i would like to clarify some points before sending the gerber files for PCB making abroad.

I've been reading some articles and post... and i woould like to know why it's talked about an "digital ground" and "Audio ground"? ... For now, i understand that the "Digital Ground" is the ground that (in my case) comes from the arduino... And the "Audio Ground" is the one that comes from the DC jack...

So... my attempt is to consider two ground planes. One with pads for switches and the other for the audio jacks.

Would this conceptual diagram be correct? 

the lower ground plane (audio)would be for control blocks (grey) for each relay (black) and from there ground pads will serve to conect footswitches.

The upper ground plane (digital) would be for isolating relay outputs and will have ground pads for send and return audio jacks...



i'm connecting the arduino to 9v and using its 5v out. Since it can provide about 500 mA, it's enough while each relay draws 30mA.

In the case that i would use a 5V regulator... it should be placed on the "digital ground plane" or even completly separated, on other pcb?

Since i'm planning to use a dual layer PCB, top layer will be used for signal routing both control and audio outs from the relay keeping them separatley as much as i can.

Well... Ithink thatis all... to any suggestion, I will be very grateful!! Thanks so much!

[ElectricDruid]

Hi Lucas,

Your diagram looks excellent to me. You've got the two ground planes separated and only joined back at the DC jack. That's pretty much perfect according to what I've been told.
Any digital noise from the Arduino board has to go "the long way around" to get into the audio circuit.

I did a PCB layout similar to this for the DigiDelay pedal I did, for similar reasons - it's a half-analog, half-digital design, so it's best to keep the two things as separate as you can.

Tom

[dschwartz]

Saludos coterraneo!!!

[ElectricDruid]

¡y saludos desde Portugal tambien!

Tom