This circuit is from LinearTechnology Applications of 1997. The circuit uses components of the time used to raise the voltage of a battery from 3 to 6 V.
The diagram shows a tone control with the LM381 IC. The circuit is from a Radio Electronics from...
Very simple, this radio control circuit for short distances was found in an Electronic Design from...
From an article in Radio Electronics magazine, May 1989, this circuit requires a dual power...