A relatively simple circuit having a resolution of 0.3 nsec has been built and used to separate particles of different mass generated by the Cornell 1.4 GeV electron synchrotron. The circuit has been in operation for a year and has played a central role in several experiments. The vernier chronotron principle of Cottini and Gatti is used so that no high speed electronics is required. The method utilizes the inherent radio frequency bunching of the internal electron synchrotron beam to produce a pulse modulated photon beam. The radio frequency itself is used to perform the timing. The circuit may also be used to make a direct coincidence between two counters with a resolution of 0.4 nsec.