A simple circuit that can be used to improve the signal‐to‐noise (S/N) ratio of a repetitive signal is described. Major simplifications in the circuit design are achieved by use of the amplifying and timing circuits of an oscilloscope to generate the input and timing signals for the boxcar integrator. The device can improve the S/N ratio of the input signal by better than 35 dB. It is usable over the 100 Hz‐160 kHz frequency range.