Bi Event Timer for Physics Lab
  Ubiquitously during experiments one encounters a situation where time lapse between two events has to measured. For example during the oscillations of a pendulum or a vibrating reed, the powering of a lamp and achieving of its full intensity. The powering of a relay and the closure of its contacts etc. Situations like these call for a time measuring device between two events. Hence this article describes a general Bi-Event timer that can be used in a physics lab for ubiquitous time lapse measurements during experiments. These measurements in turn can be used to interpret other parameters like velocity, acceleration etc. The timer described here is simple to build and accurate in performance. The Bi-event occurence can be applied as a signal to the inputs of the timer either on separate lines or along a single path in series as voltage pulses. 
Raju Baddi
physics.ed-ph physics.ins-det physics.pop-ph