功率开关管的集电极是一个强干扰源，开关管的散热片应接到开关管的发射极上，以确保集电极与散热片之间由于分布电容而产生的电流流入主电路中。为减少散热片和机壳的分布电容，散热片应尽量远离机壳，如有条件的话，可采用有屏蔽措施的开关管散热片。-power switch of the collector is a strong source of interference, the switch of the Thermal unit received should switch emitter, to ensure that the collector and heat distribution between the capacitance and because of the current inflow of the main circuit. To reduce heat and the distributed capacitance chassis, cooling unit should try to stay away from cases, if circumstances allow, there can be shielding the switch board.