Dave Platt wrote:

You'll probably want at least 64 counts per revolution, and probably
256, to get a nice smooth "feel" to the synthesizer tuning. Most such
use an optical code wheel and a pair of optosensors.

For something like a receiver tuning control, even 256 steps/rev would
sound 'jumpy'. However, you could gear it up mechanically so that even a
small movement of the control produces several pulses from the encoder.
That is exactly what happens in a mouse.

Try an old-fashioned cord drive, only in reverse.


--
73 from Ian G/GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek