555 driving a 40192 driving a 4511 driving a 7 Segment LED Display

[madamerotten]

555s are notoriously poor clocks for CMOS counters. The 555 output may often have ringing transistions that cause unwanted multiple triggers. You are remedying this by touching the clock output, because your body capacitance is filtering-out the fast transitions. A 10nF capacitor to ground should do the same thing. A better clock, however, would be an inverting Schmitt trigger connected with a single resistor and capacitor as an astable multivibrator. (One section of a CD40106 works well.)

[titoo3071]

youtube.com/watch?v=5jufhRq837­M