I finally finished my usb sound card/vox interface. The original post with the schematic is here.
I started with a small plastic project box. I cut a hole for a usb b port and made up a small usb extension cable for the soundcard. Now I can use a standard usb cable to connect it to a computer.
Next, I added the potentiometers. One controls the audio drive/volume, the next is the ptt trigger sensitivity, and the last is the ptt delay. The switch is to turn the ptt circuit on or off. In the off position, the usb sound cards works as normal.
I used 3.5mm sockets for the ptt, audio in, and audio out. The red led lights up when the ptt is engaged.