tlfong01 wrote: ↑Sun Oct 21, 2018 8:21 amCat spa tub weekend plumbing work - Part 3
Now I am order a digital float ball switch from TaoBao, for 14 yuan. I could not figure out how the things works, just by looking at the illustrations. So I need to wait for its arrival, hopefully in 2 days. I think I can use it for the cat spa tub.
Float Ball Switch
https://item.taobao.com/item.htm?spm=a1 ... 9024197118
https://item.taobao.com/item.htm?spm=a1 ... 4857563461
Float balll switch and Float ring switch
Earlier I made a laughable mistake of thinking that a float ball switch must have a floating object with the shape of a ball or sphere or at least an oblong ball like thing. So I ordered two things, one with a ball, another with a tube, with reed switch sensor inside the tube, thinking that they should work together.
But after seeing the objects, I know that they are two different things, each of which works alone, and not at all supposed to work together.
The float ball switch is sort of a all mechanical water tap, controlling the water flow, much like the float ball thing in home's traditional toilet flush tank.
The other is a floating magnetic core, used to sense the water position by switching on or off of a reed switch, to work like a push button, to be detected by say, a Rpi GPIO pin, ...
I often mixed up Reed Switch with Hall effect sensor. I once thought that Reed Switch was invented by a guy named Reed (I did not know the meaning of 'reed' then), and Hall effect sensor by another guy called Hall. I read that Hall was from Cambridge, and always thought that he was just another very smart guy from Cambridge, UK (I did not know then there is another Cambridge in US).
Just now Google told me that Reed switch was invented by Ellwood in 1936 at Bell Lab, US, and Hall effect discovered by 1879 by Edwin Hall while he was working on his doctoral degree at Johns Hopkins University in Baltimore, Maryland, US, ...