Digital counter/timer for measuring duration of motion, transition times, periods, pendulum periods, frequencies, as well as for counting events or Geiger tube pulses. Includes a speaker that can be turned on and off and power supplies for direct connection to light barriers (U11365) or a Geiger-Müller counter (U8533430). For event counting, a fixed counting period can be programmed in a range from 0.1 ms to 99999 s. Counter events (e.g. start or stop) can either be triggered by a signal to the input sockets or manually via switches. The unit includes a plug-in power supply.