General > General Technical Chat
Our knobs go to 11 - but which way round?
(1/3) > >>
nfmax:
For as long as I can remember, all* rotary control knobs on electrical & electronic equipment turn clockwise to increase whatever it is that they are controlling. On the other hand, water, air and steam control valves all turn anti-clockwise to increase the flow.

So why the difference? I assume control valves came first. Given the general preference for right-hand threads it makes sense that a threaded stem would close a valve when turned clockwise. Why we chose right-hand threads I don't know. Probably, it is down to spontaneous symmetry-breaking: the choice is initially random, but once made, sticks.

So why are electrical controls different? And when did this difference first appear? With the appearance of 'wireless', or earlier? I don't know if early electrical installations used rotary controls of any sort, or even rotary switches. Was it a deliberate choice, an independent event, or a consequence of an unrelated design decision? As a speculative example, you might have a rheostat in the filament circuit, using 'water valve' convention, so that turning anti-clockwise increases the resistance. Used as a volume control, this means that turning clockwise increases the volume. OTOH there were tuning and reaction controls on wireless sets well before volume controls became necessary - and I don't know what convention these used.

(*) Except on the Sebo vacuum cleaner I am currently repairing. Which is what prompted this post
penfold:

--- Quote from: nfmax on June 22, 2022, 11:33:24 am ---[...] On the other hand, water, air and steam control valves all turn anti-clockwise to increase the flow.

--- End quote ---

Interesting point, it is possible that because the right handed thread for right handed people gives a more natural greater force in the clockwise direction, the choice between CW and CCW could just be particular to the style of valve and whether more force is needed to open or close, perhaps against the pressure of fluid. Just thinking out loud... not thought through for all valves in all cases or cases when the thread direction is reversed to preserve convention over other optimisations.

Otherwise, when mechanical advantage or other constraints don't matter, its just a matter of having numerals in a more conventional CW direction.
Circlotron:
And clockwise would have originated from the direction of travel of the shadow of a sundial in the northern hemisphere.
Circlotron:
Left handed guitars would be a good case for a volume pot going anticlockwise to increase volume.
xrunner:

--- Quote from: nfmax on June 22, 2022, 11:33:24 am ---For as long as I can remember, all* rotary control knobs on electrical & electronic equipment turn clockwise to increase whatever it is that they are controlling. On the other hand, water, air and steam control valves all turn anti-clockwise to increase the flow.

So why the difference?

--- End quote ---

Well I can argue it's not reversed ...  >:D

Turn the volume clockwise and it increases audio output.

Turn the water faucet clockwise and it increases restriction of the water output.

Just a matter of your point of view.  :)
Navigation
Message Index
Next page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod