This circuit produces a random number from 1 to 6 on LEDs that are similar to the pips on the side of a dice. When the two TOUCH WIRES are touched with a finger, the LEDs flash very quickly and when the finger is removed, they gradually slow down and come to a stop.
When TOUCH PLATE wires are touched, the LEDs start flashing in a similar manner to a dice rolling over and over. This gradually slows down to rest and a number is displayed exactly like the spots on a dice. Buffer transistors BC547 are used to drive the LEDs adequately to obtain maximum brightness. The 10k resistors have a dual function, they are used for gating and also as current limiting for the base of each transistor. Pin 1 of the CD 4017 when it is HIGH, it will turn off the upper BC 557 transistor and also turn on the transistor driving LED 4. Also connected to pin 1 is a network of 10k resistors that produce a voltage dividing effect on the voltage to the base of the transistor driving LED 4. Since a transistor requires only about 6v, to turn it on, there's plenty of reserve in the arrangement shown. When output pin 2 goes HIGH, the only LEDs to be illuminated will be 2 and 6. This represents the number 2 on the dice. The rest of the circuit is fairly straight-forward. It comprises two building blocks: a 555 oscillator and a transistor slow-down circuit.
The TOUCH PLATE consists of two parallel wires fitted over the top of the board like two staples. The on/off switch can be either a press switch or a single pole toggle switch. If a push-button is used, it can be used to clock the 4017 to show a random number without having to wait for the slow-down. The circuit uses a 9v battery source.
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