fatigue tester - react at the speed of light

july/august 1984 react at the speed of light The human eye has a certain "built- in" delay. This fact is used for films, TV sets, and fluorescent lights, as above a certain flash frequency the eye does not notice any lask of con- tinuity. It has now come to light that the highest frequency flashing a per- son can detect is adversely affected by tiredness and alcohol consump- tion. A very small circuit is all that is needed to determine exactly what LED R3IC 84455-1 this frequency is at any time of the day or night. As the diagram shows, the circuit is very simple. It is based on an old favourite, the 555 timer, which is connected here as an astable multivibrator. Its output is connected to a LED that flashes at a certain frequency. This frequency can be varied between 20 and 50 Hz using potentiometer P1. The highest fre- quency that most people can detect is between 30 and 40 flashes per second, but one test we conducted on a Monday morning produced a startling number of blank sta...