Abstract: A weed inactivation device has at least two electrodes, whereby at least one electrode is directed to the weed. The weed activation device is used as a physical herbicide apparatus. A DC or AC power supply of any number of phases generates a voltage. This voltage is fed to an inverter that increases frequency. The current with increased frequency is fed to a harmonic filter. The harmonic filter may feed a high frequency transformer that further increases the voltage input for the voltage multiplier. The output of the previous components is fed to a voltage multiplier, such as a voltage multiplier of the Cockroft-Walton type or a full wave Cockroft-Walton type. The voltage multiplier provides different voltage levels depending on its load, so for a variable load it makes an auto-adjustable power control without any additional circuitry, processor or controller necessity.