Elenco Deluxe Snap Rover&reg - Manual (Page 43)

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Morse code was developed in the 19th century to send information over long distances using
telegraph wires and early radios. This equipment had only 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. The code sent letters as a sequence of short or long transmit bursts.
During World War II Navy ships sometimes communicated by flashing Morse Code messages
between ships using searchlights (they did this because radio transmissions might reveal their
presence or position to the enemy).
You can find more information about Morse code at websites such as
http://en.wikipedia.org/wiki/Morse_code. You can also find websites that will translate and play
back Morse code messages, such as http://www.omnicron.com/~ford/java/NMorse.html.
Project #61
OBJECTIVE: To show how capacitors can store electricity.
Electricity Station
Build the circuit and connect the jumper wires,
leaving one end of the orange jumper off as
shown. Touch the loose end of the orange jumper
to point on the Rover rear for a moment. This
fills up the 100
μ F capacitor (C4N) with electricity.
Now move the orange jumper from point to
point on the 2-snap wire. The LED (D4) lights
for a few seconds using the electricity stored in
the capacitor. Move the orange jumper back to A
to refill with electricity, and then to several
times.
If you replace the 1K Ω resistor (R2) with the
10K Ω resistor (R4) then the LED will stay on
longer but not be as bright. If you replace R2 with
the 100
Ω resistor (R1, then the LED will flash
more brightly but go out quickly.
Project #62
OBJECTIVE: To learn about Morse code.
Audio-Visual 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 ⎯ ⎯ • •
1 • ⎯ ⎯ ⎯ ⎯
2 • • ⎯ ⎯ ⎯
3 • • • ⎯ ⎯
4 • • • • ⎯
5 • • • • •
6 ⎯ • • • •
7 ⎯ ⎯ • • •
8 ⎯ ⎯ ⎯ • •
9 ⎯ ⎯ ⎯ ⎯ •
0 ⎯ ⎯ ⎯ ⎯ ⎯
Build the circuit and turn on the slide switch (S1).
Push the press switch (S2) to generate long or short
bursts of sound (from the sound & recording IC) or
light (from the D4 LED).
You can send secret messages to friends using
Morse code, which uses a series of long and short
bursts of sound or light to represent letters and
numbers. A short burst is represented by a “
• ”, and
a long burst by a “ ⎯ ”, as shown in this chart:
Notice that a capacitor is
not very efficient at storing
electricity - compare how
long the 100
μ Fs kept the
LED lit for with how your
batteries run all of your
projects! That is because
capacitors store electrical
energy while a battery
stores chemical energy.
R
O
VER REAR
B A
A
B
B
A
R
O
VER REAR
+
+