The internal control voltage signal used to switch channels when the dwell time elapses is often available to the experimenter and can be used to trigger changes in the experimental setup. In this arrangement, the MCA acts as an X–Y recorder, observing changes in the count rate as a function of the controlled experimental parameter. For example, a Geiger counter connected to an MCA in MCS mode could be used to record the amount of ionizing radiation emitted by a neutron generator at different voltages.