Rock paper scissors

Discussion in 'General Electronics Chat' started by carll, Feb 27, 2012.

  1. carll

    Thread Starter New Member

    Feb 27, 2012
    3
    0
    Hi

    I have been trying to help my 16 year old son with his GCSE project, and it must be stated that I have not done this for 30 years!!! The idea is a rock paper scissors circuit.

    The user pushes one of three switches (SW 1,2,3) which selects the correct led (D1,7,8), and when released the "computer" will also have selected its own and lit an led (D5,4,2).

    I would very much appreciate it if someone could check the circuit, I am a bit worried about the resistor used to control the scr gate voltage. I am hoping to use a CP106D with a VGT max. of 1 volt.

    All help appreciated.

    Carl.
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    I think that should be about right.

    What are the odds of the Leds taking identical ones. Like, rock & rock
     
  3. pilko

    Senior Member

    Dec 8, 2008
    213
    20
    Those SCR,s have a 5mA holding current. How will you turn them off?

    pilko
     
  4. carll

    Thread Starter New Member

    Feb 27, 2012
    3
    0
    Hi
    Thanks for the fast replies.
    If they both get the same answer then it is a draw.
    I will turn it off with SW5, the main power switch.



    Carl.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Increase the value of R2 to 1k Ohms or more. You can compensate by reducing the size of C1.

    When C1 is discharging, pin 7 of the 555 timer is connected to ground; it's an open-collector input. 9v/500 Ohms = 18mA, which is somewhat excessive. I like to keep the current through that resistor to under 10mA.
     
    carll likes this.
  6. carll

    Thread Starter New Member

    Feb 27, 2012
    3
    0
    Hi
    You were right, in the end I went to 47k to see the led's chasing, but too fast to predict.
    The circuit is built and taken to school, hopefully a good grade will result.
    Thanks for your assistance guys.

    Carl.
     
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