Switching regulators have unusual properties that have made them very popular: Since the control element is either off or saturated, there is very little power dissipation; switching supplies are thus very efficient, even if there is a large drop from input to output. Switchers (slang for "switching power supplies") can generate output voltages higher than the unregulated input, as in Figure 6.39B; they can just as easily generate outputs opposite in polarity to the input! Finally, switchers can be designed with no dc path from input to output; that means they can run directly from the rectified power line, with no ac power transformer! The result is a very small, lightweight, and efficient dc supply. For these reasons, switching supplies are used almost universally in computers.