An electronic voltage stabilizer capable of adaption to radio-frequency e.h.t. sets of any output voltage is described. Part of the e.h.t. output voltage is balanced against a reference voltage, any difference being amplified and used to control the screen voltage of the e.h.t. oscillator. An a.c. amplifier is used, d.c. voltage differences being changed to a.c. by an electronic converter and subsequently rectified.