The power circuit is a H-bridge consisting four N- channel Enhancement MOSFETs. The MOSFETs used here are International Rectifies IRF540, which can hold a maximum drain to source voltage of 400V and can pass a maximum current of 10A. The MOSFET can switch with a maximum switching frequency of about 16MHz. Although the manufacturer integrated an inverse parallel diode to the MOSFETs external inverse parallel diodes are used for added safety. Because of the on-state resistance of the MOSFET there will be a conduction loss. The on-resistance isn't the only cause of power dissipation in the MOSFET. Another source occurs when the MOSFET is switching between states. For a short period of time, the MOSFET is half on and half off. The longer that the MOSFET is in the state where it is neither on nor off, the more power it will dissipate. Because of this power dissipation to avoid the MOSFETs being damaged by heat, heat sinks are used.