Mic Pre Frontend

A digitally controlled Mic Pre Front End that accepts 3.3V inputs, and switches relays to control:

Phantom Power 
20dB Pad 
Polarity (Phase) 

A video of it working can be found here 
(speed to about 1:20) 

A video of it in prototype can be seen at here 

A prelim user manual for the product is available in PDF format from here 

What's in the box?
An unpopulated PCB
What else do I need to buy?
All other components. Bill of Materials below.


An orderable kit of parts from Mouser can be found here: