An example apparatus includes a power-factor correction (PFC) circuit coupleable to a primary load that exhibits a change in resistance with a change in applied voltage, with the respective voltage being a primary-load voltage, and current through the primary load being a primary-load current. The PFC circuit is configured to provide an auxiliary load and control current therethrough, with the respective current being an auxiliary-load current. In this regard, the PFC circuit is configured to control the auxiliary-load current such that the sum of the primary-load current and auxiliary-load current is a substantially-constant proportion of the primary-load voltage, the respective sum being a sum current.