Transistor Dice Machine       

The basics of the electronic dice is a six-state counter(binary, ring, johnson, etc). Its output is transformed to the dice pattern on LEDs. This can be made by some logic gates, or you can directly generate these patterns by a micro processor.

A long time ago, before the history of integrated circuits, there were no micro-processors, just transistors, on our planet did exist..

In the late 1960s, there were some challenges to implement an electric dice with transistors.

United States Patent 3,659,853 May 2, 1972

The above uses one UJT for oscillation, and six SCRs(Q1-Q6) for the ring counter. The diodes(D1-12) decode the states to dice patterns.

Besides reducing the number of components, it is a bit difficult to hold the counter state when stopped.
Also, it is important to ensure the frequency of the dice spot appearance. It varies if the CR delayed timings are not equal.

I designed a transistor dice machine in a bit different style.
The multi-vibrator pours the C4 charged electricity into a large capacitor C5, to rise its voltage step by step(Vc). Then the stair-formed LEDs(D11-16) light in order according to the voltage. After the last LEDs are invoked, the electricity in the large capacitor is discharged. If the vibrator oscillates in 50% duty, each dice spot appears in equal probability. The oscillation speed is variable(R3). With the stop button, it holds the dice pattern.

Transistor Dice Machine

The behavior of this circuit is delicate. The values of C4,5, R9-14 are subject to adjust.

1. Modify the small(C4)/large(C5) capacitor size (ratio 1:5-6),
2. Adjust the bias current of Q5-7 by base/collector registors,
3. Add/Remove bypass registors aside(e.g. R5) if high-bright LEDs are used. They emit lights with very weak current.

Try the SPICE simulation before making it. dice.asc(zip)

SPICE simulation

I added a piezo buzzer between Q1-c and Q2-c.

20 Apr. 2011
Osamu Tamura @ Recursion Co., Ltd.