This circuit was found in the October 1987 Radio Electronics magazine. The circuit is a PWM control with a 555. It appears that the 555 is missing a connection that would be pin 4.
This conventional series reducer circuit reduces the voltage of a 12 V battery to the selected value...
In the figure we have a converter that generates a negative voltage from a positive voltage...
This circuit covers the bands from 1.8 to 150 MHz, with plug-in coils whose characteristics are...