Oh, for those wondering how the circuit(s) can be tested, prior to building, see:
http://www.linear.com/
Upper right corner of page: "Download LTspice" -
It is free, and one of the best spice programs available.
Ah, you will not find a build for Linux - Download the Windoze build instead.
Note: They have specifically designed LTspice to run under Wine on Linux.
It even auto-detects that it is running under Wine and sets its configuration to match Wine.
"Free" and "Just Works" -
What more could a hobbyist want?