A circuit includes a clock generator to provide a clock signal, and a clock distribution circuit coupled to the clock generator and a plurality of pairs of outputs. When the induction motor of a pump-jack oil well is powered by three-phase utility power, the speed of the pump-jack shaft varies only slighty over the pumping cycle but the utility power requirements can vary by four times the average pumping power. Accordingly, a magnetic recording medium improved in magnetic properties and in lubricity can be obtained.