Not fully related, but early TV remotes used sound rather than IR. The buttons made a distinctive “click” noise, from a mechanical mechanism. The different clicks were detected in the TV and used as input.
Plus side, no batteries to deal with.
Down side, about as (un)reliable as you would expect.
Not fully related, but early TV remotes used sound rather than IR. The buttons made a distinctive “click” noise, from a mechanical mechanism. The different clicks were detected in the TV and used as input.
Plus side, no batteries to deal with.
Down side, about as (un)reliable as you would expect.
That’s wild. How did the TVs identify the distinctive sound? That seems like it would be a pretty interesting engineering trick.