Friday, 24 June 2011

My first working radio.

Just the picture of a crystal radio successfully made by myself. It manages to capture several UK channels, most notably BBC Radio 4 and Absolute Radio. For this project I used enameled copper wire BS6811 (British Standard) for the inductor coil, a Schottky barrier diode 1N5817, an a Taiwanese-made crystal earphone. The schematic of the circuit is not fancy at all; you just type in 'crystal radio' in wikipedia, scroll down to the last line and there is the simple schematic i ve been using.

By successfully producing a working radio, i have accomplished one thing in my long list -to-do-before-I-die: Making a radio. Enjoy the pictures.Its not my final destination; instead its just a start to my arduous journey into the world of electronics.

The overall picture of the radio set. The coil is of utmost importance in this invention since it forms a tuner circuit with stray capacitor ( the wire and surrounding air) and the fixed capacitor ( the blue component explained below)

The circuit. Blue component is fixed ceramic capacitor. Its optional.

The breadboard where i plant all the components. The black diode is not an ordinary diode; it is called Schottky diode. Bought it from Maplin for less than 1 pound ( got 3 of it)

A crystal earphone. This earpiece has a very low internal resistance; hence reflecting its capability of detecting small signal compared to its ordinary counterparts. I bought it from Ebay with about 2-3 pounds ( dont quite remember).

Zoom out view.

Though this radio is going well with crystal earpiece, it doesnt mean i cant use an ordinary Iphone earpiece. If the signal received is strong enuf (happens occasionally, depends on luck) you can use ordinary earpiece with a little press into your ear. Only one side of the earpiece will produce sound since the signal is mono.

Update (13 June 2012): I repeated the crystal radio design and I managed to record the AM signal received. Here is the video. I am still using the same coil with LM386 audio amplifier.The sound was in fact, louder than u will listen from the video.