precision split timer

Discussion in 'The Projects Forum' started by nouhad240, Mar 23, 2011.

  1. nouhad240

    Thread Starter New Member

    Mar 23, 2011
    3
    0
    hey guys please i need help for my project i need to make a split timer using electronics circuits and logic circuits . I'm using a NE 555 to to make my clock signal and i need to use 74LS160 and a 74LS47/48 decoder and a digital 7 segment th split timer should count to 1/10 seconds also so i need it to count to 9 min 59 sec and 9 tenth's of secs then reset my problem is i'm not able figure out the schematic thanks for your future help
     
  2. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    I don't believe a 555 will produce the accuracy you need. This seems like a project that needs a crystal time base. A PIC approach would be my choice.
     
  3. nouhad240

    Thread Starter New Member

    Mar 23, 2011
    3
    0
    thanks for the reply but unfortunately my professor demanded the usage of a 555 and no microprocessors :S can i get any more help ?
     
  4. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    If your professor can create a 555 circuit that can produce this kind of repeatable accuracy.... Wait, I'll rephrase.. If he can produce it once, he is either a genius or a magician. :rolleyes:
     
  5. nouhad240

    Thread Starter New Member

    Mar 23, 2011
    3
    0
    well i know i"m not a fan of using 555 but i'm obliged to :S thanks fort your help . another thing how can i make my BCD counter be a module 6 counter ? and the frequency of the 555 must be different for each counter rigth ( if yes any suggestions ) thanks
     
  6. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    You can always use trim pots to try to get the 555 frequency to 10 Hz.

    As to the counter, notice that 6 in BCD is 0110. An external AND gate can see thase bits and short count the 'LS160. If you have a data sheet for the IC's, you can see how to do the put them together for longer counting periods. Use the device number as a search term.
     
Loading...