The development of new computing and classification algorithms recognizing patterns in electroencephalographic (records still presents new knowledge related to functions of such a complex system as the human brain. Many workplaces occupy themselves with the processing of electroencephalographic signals. They solve mainly the issues of the detection epileptic states, Brain Computer Interface, or the detection of evocated potentials initiated by various stimuli (the light, sound, movement, etc.). As the duration of the brain reaction to a given stimulus range within tens of milliseconds, it is necessary to record the event as precisely as possible. The main aim of this paper is to describe a universal device which is able to record external stimuli during the measurement of the electroencephalographic. The designed device contains of a set of sensors and can be used with different measurement systems. The main advantages of this system are the universality, the short reaction time and the ability of recording several stimuli simultaneously.Index Terms-Brain computer interface, trigger circuit, electroencephalography.