Morse Code Transmitter
You're "on the air" with this Project! You can send Morse code signals to any radio that tunes the AM broadcast band with this two transistor circuit. You'll need an AM radio for this Project, just like you did for the last one. Tune the radio until you find an empty spot on the dial. Press the Key and listen for a tone on the radio. If you can't hear it. tune the radio to another empty spot, When you do hear the tone, slightly adjust the Tuning control of this Project for loudest sound,
You can now send Morse code messages by pressing the Key. This is also an oscillator circuit like those we've played with. So why can we send radio messages with this circuit and not others? The secret is the frequency that an oscillator oscillates at.
Oscillators used for sound oscillate at no more than 20,000 cycles per second, usually much less. But this oscillator operates at a minimum of 540 000 cycle per second up to 1 600 000 cycles-per second!
Another difference you'll see between this type of oscillator circuit and others we've used is that the output is fed to the antenna through the antenna coil (instead of being output through the Speaker or Earphone). The antenna coil actually has two coils and they're joined by ... can you guess?
There's some terms used in radio you should become familiar with, Cycles per-second are sometimes known as Hertz, A kilohertz (or kilocycle) is 1000 Hertz. And a megahertz (megacycle) is equal to 1 000 000 Hertz.