Abstract: An alarm circuit (10) includes a sensor (11), a comparator (13), a control circuit (16), and a transducer (19). The control circuit (16) controls the transducer (19) and has three modes of operation: standby mode, alarm mode, and silence mode. The comparator (13) compares the voltage of an input signal from the sensor (11) to a first threshold level during the standby mode of operation. The control circuit (16) enables the transducer (19) and transitions to the alarm mode of operation after the voltage of the input signal exceeds the first threshold level. The control circuit (16) disables the transducer (19) for a predetermined time period and transitions to the silence mode of operation after a silence signal is received by the control circuit (16). The input signal is compared to both the first threshold level and a second threshold level during the silence mode.

Abstract: The present invention relates to a gamma radiation detector probe with Geiger-Muller tube of the type which compensates for pulse losses of the Geiger-Muller tube due to dead time and linearizes its response to the number of pulses per unit of time in relation to the gamma radiation exposure rate, including a converter of the electric current from the Geiger tube into a current-dependent pulse frequency, an element for combining or mixing these pulses with those supplied by the Geiger tube, and logarithmic networks for adjusting the frequency of the converter in order to linearize the response of the complex.