A walkie talky as we called them, back when we were younger - and hell we probably still do in some respects, hence the fact my friend still refers to her cordless phone as a "walkie talky" and the principals haven't changed that much.
The common old Walkie Talky or CB radio use what we call a half duplex, that means only one person can talk at a time. We are talking and listening on the same channel.
Cell phones are full duplex, meaning two way conversation, and this is simply listening on one channel whilst talking on another, so the basic principal is basically the same, just a little more sophisticated.
Walkie-talkie typically has one channel
CB radio has 40
channels.
Cell phone can communicate on 1,664 channels or
more!
I have included a link to a circuit diagram.
http://www.freeinfosociety.com/electronics/schemview.php?id=1870There is also two links below, building the transmitter & receiver.
Transmitter:
http://www.zen22142.zen.co.uk/Circuits/rf/2bjttx.htmReceiver:
http://www.electronics-tutorials.com/receivers/regen-radio-receiver.htmTrust this helps, and please take the time to rate the answer given, thank you.
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