Low Power LM386 AM Transmitter

This is a small low power AM transmitter that can be used to broadcast your favorite audio to any AM radio in your house. It is a practical way to be able to enjoy those old radios since AM has pretty well gone the way of talk radio. The circuit is based on a design presented in the "Home Brew" section of the Antique Radio Forums. It is relatively straightforward. Audio is fed to an LM386 amplifier and amplified. The amplifier output provides voltage input to a 1 MHz clock oscillator. It is this varying supply voltage that essentially provides the AM modulation.

I shrunk everything down as small as I could get it so that it would fit into a small plastic project box. I then designed a printed circuit board to mount everything. There is a 1/8" female stereo jack for audio input, an 8' antenna wire, a 9 volt batter lead, and a small LED to indicate the unit is powered up. The pictures below show the assembled unit and a close-up of the board.