THE SOUND CIRCUIT
In the sound generator circuit, a 500Hz oscillator is
always running. This oscillator is represented by the
spinning wheel in Figure 4a.
No sound is heard
because the spinning wheel is not hitting the drum.
When the bucket in Figure 3 dumps sand, the lever
arm pushes the spinning wheel against the stop and
the small balls on the spinning wheel hit the drum,
producing a high frequency sound (Figure 4b). The
lever arm turns the sound on and represents
transistor Q7 in Figure 4c. When the lever arm is
removed, the spring pulls the spinning wheel away
from the drum and the sound stops. In much the
same way, transistor Q7 turns off shortly after a pulse
is received. This action stops electrical current from
flowing through the piezoelectric buzzer (drum),
eliminating the sound.
Just before power down,
transistor Q7 is turned on and kept on to produce the
warning sound.
THE RING COUNTER
In it’s simplest form, the ring counter can be
compared to a circle of buckets with only one bucket
filled with sand as shown in Figure 5a. Because of
the weight of the sand, the filled bucket hangs lower
than all of the rest. When a pulse is received from
the pulse generator circuit, it pushes the sand to the
next bucket as shown in Figure 5b. This process
continues passing the sand from bucket to bucket in
a circle, until no more pulses are received from the
pulse generator.
The Light Emitting Diodes (LED’s) are no more than
small electronic lights. If they are arranged in a circle
and connected to a ring counter, they can be used to
represent the ivory ball position on the roulette
wheel. When the buckets filled with sand stretch out
the springs in Figure 5, they could also close a switch
as shown in Figure 6. This would light the next light
in the circle and produce the effect of a ball spinning
around the roulette wheel. As the pulses get further
and further apart, the electronic ball will appear to
slow down and eventually stop.
THE LED’s
-5-
Spinning Wheel
Bucket Lever Arm
Spring
Stop
Drum
Spinning Wheel
Bucket Lever Arm
Spring
Stop
Drum
500Hz Oscillator
Piezoelectric
Buzzer
From Pulse
Generator
Turns Sound On
From Ring
Counter
4069
4069
C2
.0033
µ
F
R14
330k
Ω
R134
47k
Ω
R12
2.2M
Ω
U2D
U2E
11
10
9
8
R11
100k
Ω
BZ1
D2
1N4148
R16
20k
Ω
Q7
2N3904
R17
56k
Ω
C5
.47
µ
F
Figure 4
Sound Circuit
A
B
C
Ring of Buckets
Bucket filled with
sand hangs lower
than all of the rest.
Pulse Plate
Moves up when pushed.
Pulse moves sand
to the next bucket.
Figure 5
Figure 6
A
B
Bucket with
Sand
Empty Bucket
Light Off
Light On
Power
Power
