Here is a didactic set, or even serves as the basis for science fairs and games (STEM), very simple. A small battery operated DC motor rotates a roulette wheel and when switched off stops at an unpredictable number.
It is an extremely simple assembly that can be easily done, since the circuit uses only 4 components.
As we can see from the circuit shown in figure 1, we have a motor driven when a switch is pressed.
In the motor stuck the disk with the numbers that should be drawn,
When the push button is released, the roulette wheel continues to rotate for some time, stopping at an unpredictable number.
The circuit assembly is shown in figure 2.
The cardboard disk must be light enough to be driven by the motor.
In figure 3 we have a suggestion of assembly in a small box of wood or plastic.
The capacitor can have from 100 uF to 1000 uF and the number of'pe 'batteries according to the motor used.
Material list
B1 - 3 or 6 V - two or four batteries according to the motor
S1 – Push button
C1 - 100 uF to 1 000 uF - electrolytic capacitor of 6 V or more
M1 - Small engine
Several:
Soldering wires, roulette, battery holder, mounting box.
