tikker
noun
tik·ker
variants or ticker
ˈtikə(r) 
plural -s
: a form of interrupter used in the early days of radio as a detector of continuous waves consisting of a rapidly rotating wheel and a fine wire brush with the current made and broken by momentary contacts between the brush and a continuous strip of conducting material in the rim of the wheel
Word History
Etymology
tikker alteration of ticker entry 1