A General Purpose Timer/Counter
John Malcolm Walker, W. Nichparenko · Perceptual and Motor Skills · 1972
This paper discribes a solid state digital display instrument that functions as: (1) a reaction timer, (2) an interval timer, (3) an event counter, or (4) a predetermining counter. Parts for the instrument can be purchased for approximately $125 and assembled in 25 to 30 hr.