Re: Morse transmitter

Michael Black wrote:
Spanny Gobuck (spanny@xxxxxxxxxxx) writes:
I'd like to build a morse transmitter/receiver for educational purposes for the kids. Has anyone any ideas about where i could get buy such stuff? Range isn't important. Also are there any regulations to consider?

If you use a traditional code transmitter, you'll need to have a receiver
with a BFO, a Beat Frequency Oscillator, so you'll hear a tone in the receiver
rather than just a thump.

That means either a special receiver, or adding a BFO to it.

But if you use an AM transmitter, and instead of a microphone feed
an audio oscillator into it (turning the audio oscillator on and off
with the code key), then any AM receiver will work. Whatever the tone
at the transmitter, you will hear that in the receiver's speaker. This
would work for FM transmitters, too.

So if the project is to teach code, or demonstrate it, you can use
any "wireless" microphone type transmitter, and feed a keyed audio
oscillator into the microphone input. Then use a regular broadcast
receiver to receive it. All those adaptors they now have to connect
MP3 players to existing radios would work too, just feed the audio
oscillator into the audio input of the adaptor.

There was a time when cheap 27MHz (and later 49MHz) walkie talkies
would include a button to send code, complete with the morse
code chart on the cover, and they all used the same principle.

If you actually want to build the transmitter, then it shouldn't
be hard to either find a schematic that includes such an audio
oscillator from a time when that sort of thing was common, or
any "wireless microphone" schematic and add an external audio oscillator.

Michael

Hi Michael,

Thanks to you and the other OP who replied. I did a google search but the top two sites were unobtainable :-(

I'd like to have a portable transmitter so it'd be a bit more fun for the kids -- not to mention grown-ups ;-) I'd like something that resembles equipment issued during WW2 -- with modern circuits instead of valves, though. I guess I'm probably looking for a DIY kit.
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