This paper describes an on-site developed interface amplifier and timing generator unit for the control of operation of an X-ray spectrometer, aimed at obtaining off-line time-resolved pulse height analysis spectra, using at single channel of a digital transient recorder and a histogram algorithm. This unit, implemented in a low noise NIM module to be inserted between the amplifier and the transient recorder, generates a trigger pulse and time information for the digitizer, conditions the amplifier output signals to the digitizer input characteristics, reports the occurrence of pile-ups and prevents collisions between time and event pulses. Tests and operation on the TCV X-ray spectrometer have shown that the unit fulfils the design requirements. (C) 2000 Elsevier Science S.A. All rights reserved.