Found in the 1990 special issue of Radio Electronics Experimenter magazine, this circuit uses an automobile ignition coil. Adjustments can be made to suit the coil.
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...