Elenco Circuit Maker Sound Plus 200 - Manual (Page 50)

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Project #106 Audio Morse Code
Use the preceding circuit, but change the
5.1KW resistor (R3) to the 100W resistor (R1).
While holding down the press switch (S2),
move the slider on the adjustable resistor
(RV) around. When the slider is near the
100W resistor you won’t hear any sound, but
the circuit is still working. This oscillator circuit
is making sound waves at a frequency too
high for your ears to hear. But your dog may
hear it, because dogs can hear higher
frequencies than people can.
Project #107
Dog Whistle
Build the circuit and set the adjustable
resistor (RV) control lever to the left.
When you press down on the press
switch (S2) you will here a tone. By
pressing and releasing the press switch
you can generate long and short tones
called Morse code. For International
code, a short tone is represented by a
“+”, and a long tone by a “–”. See the
chart above for letter or number
followed by code.
Project #105 Morse Code
This simple circuit can be used for communication. Press the press switch
(S2) in long and short bursts to make a pattern of light flashes representing
the dots and dashes shown in the Morse Code table shown. You can use
Morse Code and this circuit to send secret messages to some friends in the
room without others knowing what you’re saying.
If you have a strong flashlight or searchlight then you can send messages to friends
far away at night. During World War II Navy ships sometimes communicated by
flashing Morse Code messages between ships using searchlights (because radio
transmissions might reveal their presence to the enemy).
Years ago Indians would send messages to other tribes using smoke signals
and a special code.
Morse Code: The forerunner of today’s telephone
system was the telegraph, which was widely used
in the latter half of the 19th century. It only had two
states - on or off (that is, transmitting or not
transmitting), and could not send the range of
frequencies contained in human voices or music.
A code was developed to send information over
long distances using this system and a sequence
of dots and dashes (short or long transmit bursts).
It was named Morse Code after its inventor. It was
also used extensively in the early days of radio
communications, though it isn’t in wide use today.
It is sometimes referred to in Hollywood movies,
especially Westerns.
MORSE CODE
A . _
B _ . . .
C _ . _ .
D _ . .
E .
F . . _ .
G _ _ .
H . . . .
I . .
J . _ _ _
K _ . _
L . _ . .
M _ _
N _ .
O _ _ _
P . _ _ .
Q _ _ . _
R . _ .
S . . .
T _
U . . _
V . . . _
W . _ _
X _ . . _
Y _ . _ _
Z _ _ . .
Period . _ . _ . _
Comma _ _ . . _ _
Question . . _ _ . .
1 . _ _ _ _
2 . . _ _ _
3 . . . _ _
4 . . . . _
5 . . . . .
6 _ . . . .
7 _ _ . . .
8 _ _ _ . .
9 _ _ _ _ .
0 _ _ _ _ _
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