The mini-breadboard version of the NT7S code practice oscillator along with 9V battery fits perfectly into an Altoids tin (the preferred enclosure of tinkerers everywhere). This evening I spent some time wiring up the board to the jacks and power switch.
When I plugged in the headphones and my straight key, I was greeted with a continuous tone, and nothing happened when I tapped the key. Crap, I must have a short somewhere. After a bit of looking around on the board, I went back into the house to grab the schematic, and then realized I had plugged things into the wrong jacks. Swapped the headphones and key and got nice sounding tones when I tapped the key, just as expected. Works great and everything sits in the tin nice and securely. The battery slides around a tiny bit, but that’s not a big deal.
Now I can bundle up my straight key and some headphones and practice wherever I want.