How to design a DIGITAL TIMER for variable Duty cycle and Frequency?

Discussion in 'The Projects Forum' started by archana91, Jan 7, 2012.

  1. archana91

    Thread Starter New Member

    Jan 7, 2012
    I need to build a Digital timer in which the inputs are Duty cycle (Range : 10 to 90%) and Frequency (Range : 10 to 120 cpm). My project guide insisted me to use oscillator and frequency dividers to obtain wide range and not to use 555 timer.
    Can anyone tell me how to design the circuit??
    Plzzzzzz help me!!!!
  2. Bernard


    Aug 7, 2008
    Are you wishing to measure the period of both parts of the input signal?
  3. archana91

    Thread Starter New Member

    Jan 7, 2012
    Yes. Can you tell me how to obtain duty cycle in steps of 5% using 4017?
    See the circuit which i have attached. I'm getting output of duty cycle 10 to 80% in steps of 10% from the 4017 (Johnson decade counter)?
    How should I modify the circuit to get output from 10% to 90% DC which increases in steps of 5%?
  4. BillB3857

    AAC Fanatic!

    Feb 28, 2009
    Think of how many different states are needed for 5% steps. How does the 4017 you are using now provide the 10% steps? Hope these hints help.