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Open 7400 Competition / [Entry] AM Radio Transmitter
My 7400 contest entry is an AM Radio Transmitter, which nicely complements another entry. The TX frequency is digitally tunable from 520kHz - 1.6MHz, although this part of the circuit is open loop, so tuning to a specific frequency may require a slight adjustment on a potentiometer. The RF section is strong enough to broadcast across a room, but weak enough that it shouldn't interfere with anything important. Here is a screen shot of a 1kHz audio signal on a 930 kHz (approx) carrier. Full circuit information, including the theory of operation, is outlined on my website.
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Demo Video: http://http://www.youtube.com/watch?v=PZFEEiO3gzU
Detailed Write-up: http://http://andrewsteadman.ca/myprojects/projects/7400amtx/wiki
Cheers,
Andrew