This very low current circuit was found in the April 1995 Electronics Now magazine. The frequency should be chosen for maximum efficiency according to the small transformer used.
This frequency shift modulation circuit was found in the November 1994 issue of Electronics Now...
Found in a 1964 Electronic Design this circuit makes use of components of the era. The output is 2 V...
This circuit using 2N2904 general purpose transistors is from a December 1993 Electronics Now...