Seventy years ago this month, the February 1956 issue of QST showed this circuit for a very simple code oscillator, using the venerable CK722 transistor. This was actually a simplification of an earlier circuit, which had been updated by George Carson, W0JV.  The oscillator runs on 1.5 volts, but for greater volume, that could be upped to 3 volts.

Carson was a professor at the University of Iowa, and his call is still held by the Iowa City Amateur Radio Club.