A portable defibrillation system, comprising: a high voltage switch and current control circuit connectable to and fed by an AC power source; a high voltage transformer fed by said high voltage switch and current control circuit; and a pair of electrode pads (12, 12') connected to said high voltage transformer; characterized in that: said system further comprises J a computer-based controller operationally connected to said high voltage switch and current control circuit, said controller being adapted to govern the application of current to said high voltage transformer by providing an automatic trigger; a positive half-cycle detector, said detector being adapted to detect the beginning of a first positive half-cycle of the AC power source signal occurring in response to said automatic trigger; a time delay circuit, said circuit adapted to enable a time delay counted from said detected beginning; and a pulse width generator, said generator being adapted to generate a pulse starting after said delay and having a specified width, said pulse being used as a gating signal to a high current switch adapted to apply the AC power source signal to said high voltage transformer and hence, via said electrode pads, to the patient. a high voltage switch and current control circuit connectable to and fed by an AC power source; a high voltage transformer fed by said high voltage switch and current control circuit; and a pair of electrode pads (12, 12') connected to said high voltage transformer; said system further comprises J a computer-based controller operationally connected to said high voltage switch and current control circuit, said controller being adapted to govern the application of current to said high voltage transformer by providing an automatic trigger; a positive half-cycle detector, said detector being adapted to detect the beginning of a first positive half-cycle of the AC power source signal occurring in response to said automatic trigger; a time delay circuit, said circuit adapted to enable a time delay counted from said detected beginning; and a pulse width generator, said generator being adapted to generate a pulse starting after said delay and having a specified width, said pulse being used as a gating signal to a high current switch adapted to apply the AC power source signal to said high voltage transformer and hence, via said electrode pads, to the patient. J a computer-based controller operationally connected to said high voltage switch and current control circuit, said controller being adapted to govern the application of current to said high voltage transformer by providing an automatic trigger; a positive half-cycle detector, said detector being adapted to detect the beginning of a first positive half-cycle of the AC power source signal occurring in response to said automatic trigger; a time delay circuit, said circuit adapted to enable a time delay counted from said detected beginning; and a pulse width generator, said generator being adapted to generate a pulse starting after said delay and having a specified width, said pulse being used as a gating signal to a high current switch adapted to apply the AC power source signal to said high voltage transformer and hence, via said electrode pads, to the patient.