Elenco Electronics 202 - Manual (Page 80)

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Project #181 Morse Code Generator
OBJECTIVE: To make a Morse code generator and learn to
generate code.
Project #182
LED Code
Teacher
OBJECTIVE: A method of
learning the Morse code without
all the noise.
Use the circuit from project #181
shown above. Replace the
speaker (SP) with a 100
Ω resistor
(R1) so you can practice
generating the Morse code
without the loud speaker. Have
someone transmit code and
watch the LED (D1). Tell them
the letter or number after each is
generated. When you have
learned code, replace the
speaker.
OBJECTIVE: To make a ghost
like special effect from the Morse
code generator.
Project #184
LED &
Speaker
OBJECTIVE: To improve
Morse code skills and visual
recognition.
OBJECTIVE: To make an
oscillator that only a dog can
hear.
Project #183
Ghost Shriek
Machine
Use the circuit from project #181
shown above, but change the 1k
Ω
resistor (R2) to a 10k Ω resistor
(R4), and 0.1 μF capacitor (C2) to
the variable capacitor (CV). While
holding the press switch (S2)
down adjust both the adjustable
resistor (RV) and the variable
capacitor for a ghost like sound.
At certain settings, sound may
stop or get very faint.
Use the circuit from project #181
shown above. Try and find a
person that already knows the
Morse code to send you a
message with both sound and
LED (D1) flashing. Try in a dark
room first so LED is easier to
see. Morse code is still used by
many amateur radio operators to
send messages around the
world.
Use the circuit from project #181
shown above, but change the 1k
Ω
resistor (R2) to the 100 Ω resistor
(R1). While holding down the press
switch (S2), move the slider on the
adjustable resistor (RV) around.
When the slider is near the 100
Ω
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 #185
Dog Whistle
When you press the press switch (S2) you will hear 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 below
for letter or number followed by 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 – – – – –