Retro mediumwave detector-radio

prusaprinters

Old school detector radio technology meets 21st century 3d-printing. This is a simple to build and use detector radio for the mediumwave band. And yes - it runs without batteries (by only using the transmitted radio energy). We developed this project for a kids day at our ham radio club. It is fun to build and to use - no matter if you're 9 or 99 years of age! For most of the most popular stations in Europe you'll need about 28 turns which gives an impedance of 50 - 180 uH. Frequency range is about between 550kHz and 1100kHz. Instructions Things you'll need 1x the set of printed parts (coil housing, chassis, slider and cap) 1x ferrite rod (standard type with two flat sides), length: 4 cm (1.57inch) 1x diode (germanium type) AA 112 or similar 1x ceramic capacitor 470 pF 1x crystal earpiece (very high impedance of about 2000 ohms) 30 m / 98 feet of 0.4 mm / AWG 26 laqued copper wire for the antenna and ground connection. Construction manual Plug the ferrite rod into the slider (usually no glue is needed, but putting the slider into hot water can help when it's too tight. Try to put the ferrite into the coil housing and make sure it slides smooth. Use a file to broaden it. Put the cap on to prevent loss or damage of ferrite rod. Wind 28 turns of 0,4 mm lacqued copper wire on the coil housing and leave about 10 cm loose to connect the coil. Add diode (black ring directs away from the coil) and condensator to the chassis (like on the photos) Add the coil to the chassis, strip the two wires and connect (wind or solder) them with diode and condensator. Strip the ends of the two earplug wires and connect them with the free end of the diode (the side with the black ring) and condensator Turn about 20 m of lacqued copper wire on the chassis (side close to the coil) as antenna wire. You can use the two small holes to create a pull relief. Strip the end on the chassis and connect it to the diode / condensator corner. Turn about 10 m of lacqued copper wire on the chassis (side away from the coil) as ground connection. You can use the two small holes to create a pull relief. Strip both ends and connect the chassis side to the condensator. If you like glue a sticker or piece of paper into the pit and use it as scale. That's it! First Contact Stretch out the antenna and connect the ground wire to an earthed device like central heating radiator, water tap or tent peg when you're outside. !NEVER ever to a power socket! Use the slider to find a station. Listen and mark the frequency on the scale. Have fun building and using your own detector-radio Category: Audio