At starting wait for few seconds to stabilize all ICs.
Any counter without Clear (CLR) Button is useless. You can't clear counting at your desire. So we made a JK-FF by NAND Gate with Preset and Reset Button.This 0-39 counter is running on our JK-FF.
Preset point is fixed with Logic source 1 and Reset / Clear (CLR) Button is located just below the display. At any point if you make the Reset Button 0 then then FF will be Clear and show 00. Again on Reset 1 counting will be start from 01.
