Ultra-miniature Radio Receiver

A coat button,yes-that's exactly how big this ultra-miniature radio receiver should turn out to be.The key to its compact size  a button cell and a button sized piezo speaker.The receiver tunes in several local broadcast band stations and gives a reasonable amount if volume.The circuit may be built on to a dot matrix board which will give a reasonable amount  of compactness.

As shown in schematic  a the circuit uses just one custom coil L1 which is wound as shown in schematic b L2 is a conventional IFT used in radio sets.T1 is the main component that forms an HF,RF amplifier having just one stage.T2 serves as a single-stage amplifier .D1 is 1N914,but any other suitable  substitute may be used.The piezo speaker may be a button type or simply a flat piezo element.The connection of the element are shown in Picture

The Schematic a Ultra-miniature Radio Receiver

The Schematic b Ultra-miniature Radio Receiver

 

 Picture

Coming to power, it is obtained,as stated earlier,from a single watch cell.Use a thicker(more current) one for longer life ,or one can use lithium batteries or even Ni-Cd button Cells.

Well, so the miniaturization miracles work on receivers too-not just computers.