Morse Code Keyer (2)
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R1,R4 = 100K IC1 = LM555
R2 = 10 ohm S1 = 3-pole, switch toggle, on-on
R3,R5 = 1K S2 = Morse keyer
P1 = 500 ohm J1 = Jack, mike-output
C1 = 5uF/16V LS1 = Loudspeaker, 8-ohm, up to 2 watts
C2,C4 = 0.1 uF Batt1 = 9-Volt Alkaline battery
C3 = 0.01uF
(LS1) can be any 8-ohm type up to 2-watts. Supply voltage for this circuit is up
to 15 volts, but 12V is more desirable if you choose to go with a adapter. If
possible, try to use a mylar or polyester kind of capacitor for C2.
IC1 is a
CMOS MC1455P or
equivalent, Timer/Oscillator. This type of cmos IC consumes a lot less current
when used with the 9-volt battery, but if you don't want to spent the money then
the LM555, NE555,
etc. are fine too and are pin-for-pin compatible with each other. The timing
circuit is formed by R1, R3, and C3. Resistors R4 & R5 are a voltage devider
to reduce the microphone output to a safe level. Potentiometer P1 can be used to
control the 'Pitch'. Capacitor C5 is used as a bypass capacitor to clean up
unwanted noise. C1 is specified as a 5uF electrolytic but a standard 4.7uF will
work fine too.
S2 is your Morse-key or Paddle. S1 switches between your
speaker and the microphone output jack (J1), which you can hookup to your
stereo, amplifier, or cassette player. Match J1 with the jack you hook it up
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