A solid-state digital integrating X-ray dosemeter is described in which the voltage excursions of the integrating capacitor are controlled by the trigger and reset voltages of a transistorized Schmitt circuit. Before triggering, the Schmitt circuit presents a very high input impedance to the integrating capacitor, whereas after triggering its input impedance falls by comparison to a very low value, enabling the integrating capacitor to discharge to the Schmitt reset voltage level in a few msec only; adequate compensation has been incorporated for likely changes in temperature and mains supply voltage.