This is a (QRP) AM transmitter I designed in a couple days, in order to learn how radio transmitters work. Even though I have no use for it, as I am not a radio amateur/radio broadcaster, I decided to share it anyway, hoping it will be useful to a QRP/Radio enthusiast.
Theory of operation.
An electret microphone picks up the sound to be transmitted. The output of the electret microphone is amplified by the AF amplifier, in order to be useful to the modulator stage. The modulation is achieved by the analog multiplier IC, while the carrier wave is externally introduced.