The utility model discloses a the DC load supply circuit, including rectifier bridge T, electric capacity C2, relay K and loudspeaker B, rectifier bridge T's voltage input port 1, 3 primary winding N2that connect transformer W, transformer W's secondary N1 connects 220V commercial power circuit, does rectifier bridge T's voltage output port 2 connect electric capacity C2 and relay K's contact K 1, relay K's contact K 1 other end connecting resistance R1, resistance R2, triode V1's projecting pole and triode V2's collecting electrode. The utility model discloses the DC load supply circuit adopts the triode to constitute the compound adjustment pipe, carries out the regulation control to output voltage, has that the pressure drop is low, efficient advantage, still utilizes the relay to realize short -circuit protection's function simultaneously, and automatic cutout load electric loop when taking place the short circuit is and send the chimes of doom, consequently has convenient to use,the function is various and efficient advantage.