David Hugues (1831-1900). 1868 illustration of the Welsh-American scientist and musician David Edward Hughes. Hughes is best known as co-inventor of the microphone and teleprinter, inventor of the spark-gap transmitter and inventor of the crystal radio. He also independently invented a semiconductor rectifier diode, which he used to invent the crystal radio detector for the world's first radio transmitter and receiver. He was elected a Fellow of the Royal Society in June 1880 and won their Royal Medal in 1885.