Electronic Dice

Circuit Diagram
Components Required
  1. Resistors
    1. R1 (22 kilo ohms, 1/2W)
    2. R2 (12 kilo ohms, 1/2W)
  2. Integrated Circuit
    1. IC1 (555)
    2. IC2 (CD4017)
  3. Capacitor
    1. C1 (0.022mfd, 50V)
  4. LED
    1. 6 LEDs
  5. Miscellaneous
    1. S1 Push-to-on switch (single pole)
    2. S2 Toggle switch
    3. Battery 9V
    4. PCB or Breadboard
    5. Flexible Wire
    6. Soldering rod etc..
Principle and Working

It is good idea to put this circuit in a box and mark/write each LED with number 1 to 6. Now, when switch S1 is pushed momentarily, any one of the 6 LEDs will glow. The Number marked for glowing LED becomes dice's output. Every time S1 is released, new LED will glow randomly. Chances for each LED to glow is 16.66%.

This circuit makes use of two ICs, IC555 and IC-CD4017. IC-555 is used as square wave generator, and IC(CD4017) as a counter. Actually CD4017 is a divide-by-10 johnson-counter with 10 decoded outputs. IC555 simply generates clock for CD4017, and the clock frequency is controlled by R1 and C1. Counter CD4017 starts counting from 0 to 9 by putting high voltage on each of the 10 pins (one after another). The High voltage shifts from one pin to another on every positive edge of the clock. Since, in our circuit pin-5 is shorted with pin-15(reset), the counter gets reset after reaching 6, and again starts from 0. Now, when S1 is pushed, IC555 generates clock for CD4017. This clock enables CD4017 to count from 0 to 6 by putting high voltage on each of the 6 pins (one after another). These 6 pins are connected to 6 respective LEDs. When S1 is released, high voltage gets latched to any one of the 6 pins, and this becomes output of the DICE.