Elenco Circuit Maker Skill Builder 125 - Manual (Page 57)

Project #115
Light to Dark
Project #114 Morse 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 _ _ _ _ _
Project #116
Power Shifter
-56-
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 below. 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.
Turn on the slide switch (S1), the
brightness of the LED (D1)
depends on how LITTLE light
shines on the photoresistor (RP).
The resistance drops as more light
shines, diverting current away from
the NPN transistor (Q2).
When you turn on the
slide switch (S1), the
LED (D1) is on and
the lamp (L1) is off.
Push the press
switch (S2) to bypass
the LED. The lamp
turns on and the LED
turns off. This shows
how switches can be
used to shift power
between different
devices.
CM-125_Manual_031514.qxp_CM-125_Manual_031514 4/2/14 12:20 PM Page 57