  Affordable electronics for instrumentation play a vital role in academia
since research budgets are tight nowadays. In this paper a low-cost open-source
high-frequency portable Raspberry Pi-based pulse counter is presented. Although
it is designed as a $ 2 $ channel counter, it can be easily modified to a $ 4 $
channel counter. It provides a relay control interface for experimental-setup
integration and counts pulses up to $ 10 $ MHz frequency. Presented system is
proved to be accurate by an Xray transmission rate measurement experiment.
