
'Cat's whisker' Crystal Radio
1920-1925
1920-1925
1923 - 2015
1920 - 2007
1926
1931
circa 1920
1927
1927
1920
1924
circa 1930
1928
1920-1929
1932
1931
1931
1927
1930
circa 1930
1920-1925
1928
1932
1933
1925
1924
1955; 1830
1925-1928
1928
1924
1927
1933
1926
1922-1923
1922-1923
1921
1922-1923
1922-1923
1921-1926
1925
1920-1929
1920-1930
1920-1930
1923
1924-1927
1934
1921
1931
1920
2000-100 BCE
Before 1932