Positive and negative symmetrical dual power supplies using only five components

In imported electronic equipment, you can often see circuits that use positive and negative power supplies as shown in the figure to supply power to the op amp integrated block. Its characteristics are: 1. It is very convenient to make or select a power transformer, and the secondary winding of the transformer does not need to have a center tap. 2. The positive and negative power supply voltages are symmetrical. 3. The utilization rate of electric energy is high. 4. Simple structure. Practice has proved that: on the premise that the power capacity of the power transformer is sufficient, the capacitance capacity and the secondary winding diameter of the transformer are appropriately increased. This circuit can also be used for low-power audio amplifiers for positive and negative symmetrical dual power supply.