A switching power supply circuit includes a direct current (DC) power supply input, a first transistor, a capacitor, a first resistor, a second resistor, a switching circuit including a second transistor, and a first transformer including a first primary winding and a secondary winding. The DC power supply input is connected to a drain electrode of the first transistor via the capacitor. A gate electrode of the first transistor is connected to ground via the first resistor, and connected to the drain electrode of the first transistor via the second resistor. The DC power supply input is connected to a source electrode of the first transistor via the primary winding. The source electrode of the first transistor is grounded via the second transistor. The secondary winding is structured and arranged to drive a load circuit.