High voltage can be generated in defibrillators by using voltage multipliers. For this purpose, direct current has to be converted to either alternating current or pulsed direct current. This can be done using an oscillator circuit as in an inverter. Alternating current voltage can also be multiplied using step up transformers. Voltage multiplier circuits can generate very high voltages needed for defibrillation, usually of the order of 2500 volts. The high voltage generated is used to charge a high energy, high voltage capacitor so that it can be discharged within a fraction of second to produce complete depolarization of the heart to achieve successful defibrillation. Simple voltage multiplier circuits are arrays of diodes and capacitors, arranged in a particular sequence.