4-37 little or no variation. Regulator circuits sense changes in output voltages and compensate for the changes. Regulators that maintain voltages within plus or minus () 0.1 percent are quite common. Figure 4-30.Block diagram of a power supply and regulator. Series and Shunt Voltage Regulators There are two basic types of voltage regulators. Basic voltage regulators are classified as either SERIES or SHUNT, depending on the location or position of the regulating element(s) in relation to the circuit load resistance. Figure 4-31 (view A and view B) illustrates these two basic types of voltage regulators. In actual practice the circuitry of regulating devices may be quite complex. Broken lines have been used in the figure to highlight the differences between the series and shunt regulators. Figure 4-31A.Simple series and shunt regulators. SHUNT REGULATOR. Figure 4-31B.Simple series and shunt regulators. SERIES REGULATOR.