This is a Reaction Timer with 4026 chip. 4026 is a counter and display decoder. Steps for implement Reaction Timer Circuit: [1] meet 4026. Set DEI - Display Enable In High; INH - Clock Inhibit Low and apply a pulse in Clock Pin; [2] Next connect two 4026 by Carry Out Clock pin; [3] Set 555 timer in Astable Mode as pulse generator; [4] Add another 555 timer in Bistable Mode; This will start and freeze the counter; The RESET pin is Low when active; [5] Add another one 555 timer in Monostable Mode; this one will cause a delay on circuit and start it on.
Proteus File:https://www.dropbox.com/s/iku806gn1og...
Schema:https://www.dropbox.com/s/beo3d4gqefg...
Book: Make Electronics: http://www.amazon.com/Make-Electronic...