Coin Tosser (MIN049e)

This circuit simulates the flipping of a coin by merely pressing S1. Of course, the electronic version, if used for important decisions (or experiments), can’t be loaded or weighted and is 100% random.

The circuit has two LEDs that flick alternatingly, in a frequency rate determined by C1, when power is ON. When you press 81 the circuit stops immediately and only one LED remains ON.

Power supply can range from 5 to 12 volts, and this means that you can use AA cells in a portable version.

Some components can be altered according to the intended application: C1, for instance can be altered in a range from 0.01 to 0.47 µF.

You can also use a touch sensor to stop the tosser or increase R1’s value to up to 10,000,000 Ω.

The schematic diagram for the coin tosser is shown in figure 1.

Figure 1 – Schematic diagram for the project

Only one gate a 4093 IC is used as oscillator to produce random pulses in this circuit.

Components placement on a homemade printed-circuit board is shown in figure 2.

Figure 2 – Components placement on a PCB

The circuit can easily be housed in a small plastic box.

Position of the polarized components, such as the LEDs and electrolytic capacitor, should be observed.

Ideas to Explore

To learn more about the circuit or to get better performance:

Instead of using LEDs, transistors can be used to drive incandescent - lamps.

S1 can be placed as far as you want from the circuit. Common parallel wire can be used for this task.

Explain how a flip-flop works and how you can guarantee that the circuit is 100% random.

Science and uncommon applications:

You can conduct ESP (Extra-Sensory Perception) experiments using this circuit. S1 can be placed far from the LEDs for better results.

Experiments with probability theory can be conducted using this circuit.

Try to couple a sequence generator to the oscillator used in this circuit to get a 1-to-10 raffle circuit.