Abstract: A fast power supply for an image intensifier tube used in night vision devices. The tube includes a microchannel amplification wafer placed between a photocathode and an output screen. The supply of the tube delivers a reference voltage to a first terminal of the wafer, a variable voltage to the second terminal of the wafer, a variable photocathode voltage and an output screen voltage. The illumination of the output screen is measured by its screen current. Beyond one screen value, and in order to maintain constant output illumination while avoiding dazzle, the voltage at the second terminal of the wafer is slaved to the changes in the screen current and is different from the photocathode voltages fixed. The circuit for controlling the circuit at the second terminal of the wafer includes a high voltage amplifier with transistors having small quiescent consumption and high control speed for decreasing or increasing the voltage as a function of the variations in the screen current.