Apparatus can limit power by limiting the duty cycle of current carried by a pair of lines. The lines intermittently conduct electrical power. The apparatus has a clock, a converter and a switch system. The clock can provide a timing signal. The converter is driven by the lines and can convert its intermittent electrical signals to uninterrupted power and can supply this uninterrupted power to the clock. The switch system responds to the timing signal and can periodically interrupt at least one of the lines.
