I used 1/16th of the time because it was convenient for the ICs I used. There is nothing magical about that figure.
I assume you're taking the output from pin 3 of the 4060 (output Q14). Alas while you have Q13 and Q12 available, you don't have Q11. But you could get a 1/8th duty cycle by logically ANDing Q12, Q13 and Q14.
Get a 4081 IC (CD4081, etc). It's a 14 pin DIL package containing 4 AND gates each with 2 inputs. Connect :
Pin 7, 8, 9, 12, 13 to 0V (that also ties the inputs of 2 gates you're not using to ground).
Pin 14 to the +ve supply rail
Pin 1 to Q14 (pin 3 of the 4060)
Pin 2 to Q13 (pin 2 of the 4060)
Pin 6 to Q12 (pin 1 of the 4060)
Pin 3 to pin 5 (this couples the output of the first AND gate to one input of the second, thus making a 3 input AND gate).
Take the output from pin 4 of the 4081.
If you're using 74HC series ICs then the IC you want is the 74HC08. The pinout is different to the 4081. In that case :
0V to 7, 9, 10, 12, 13
Positive supply to 14
Q14 to 1
Q13 to 2
Q12 to 5
Link 3 to 4
Take the output from 6.
No calculations needed
