Description: Apple II and IIe: Power Supply Input Frequency Limitations Header: Apple II and IIe: Power Supply Input Frequency Limitations This article last reviewed: 18 September 1987 The Apple II and IIe power supply is a switching power supply. It is designed to accept 107 to 135 volts from DC to 60 Hz. It will also work at up to 400 Hz but this endangers a circuit which protects the supply from shorting to the point that the protecting circuit will not work. Keywords: