We propose an Automatic On-Off Switching (AOS) repeater that is switched off automatically when there is no active user within its coverage. With the AOS repeater, we can reduce the unnecessary noise enhancement. The reverse link capacity of a DS/CDMA system with AOS repeaters is analyzed mathematically and compared with that of a system with conventional repeaters. Also, the AOS circuit in a repeater can protect the reverse link capacity of a DS/CDMA system from excessive noise enhancement by abnormal repeaters. From the numerical results, noticeable improvement with the AOS repeaters is shown.