| abstract |
A circuit improvement is disclosed for use in an electron capture detector of the type including an electron capture cell, means for applying polarization pulses to the cell to derive a cell current, means for varying the pulse rate to maintain the cell current constant, and means for converting the pulse frequency to an analog signal indicative of the concentration of an electron-capturing component. Pursuant to the improvement, the pulse rate is varied by means which include an electrometer-amplifier for receiving the cell current and providing an output indicative of cell current departure from a reference current; an integrator for receiving the electrometer-amplifier output, the integrator generating a saw-tooth wave form, the slope of which is proportional to the magnitude of the electrometer-amplifier output signal; means for comparing the integrator output signal with a fixed reference voltage and for generating a triggering pulse when the two are equal; and pulse generator means coupled to the comparator output for generating the polarization pulses in response to the triggering pulses. |