Electrotherapy apparatus

An apparatus for producing analgesia in a patient through electrical signals applied by electrodes to the patient's body, the apparatus comprising electrodes for application to the patient's body and a signal generator which is connectable to the electrodes, wherein the signal generator is arranged to generate a biphasic waveform comprising successive cycles each containing a positive and negative pulse, and comprises:

• a converter for producing a desired voltage from a power supply;
• a first capacitor which is in electrical connection with said converter and which is arranged to provide the positive pulse to one of said electrodes;
• a second capacitor which is in electrical connection with said converter and which is arranged to provide the negative pulse to one of said electrodes;
• wherein said first and second capacitors are respectively connected to an output by a corresponding first and second pathway, the pathways including respective switches, and wherein the signal generator includes a controller arranged to control the operation of the switches to cause alternate discharge of the first capacitor through the corresponding first pathway and the second capacitor through the corresponding second pathway to generate said positive and negative pulses, and wherein the first and second capacitors are connected via respective diodes to a common supply generated by the converter, and wherein the first and second pathways are provided respectively by two arms of an H-bridge.