Level sensors, but not touching the water

Request new hardware or ideas for the controller
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jason
Posts: 18
Joined: Fri Apr 27, 2012 2:29 am

Level sensors, but not touching the water

Post by jason »

....and even better, as they are not inside the tank !!!!


Some years ago, like 5-6, i made an ATO with stainless steel electrodes, some Darlington transistors and a relay, as I was always getting snails stuck in the float switch. It ended up being edited in a french magazine for fresh water tanks, I was so freaking happy !

This thing was working with less than 12uV (micro) and was perfect for fresh water, and I know some people used it for SW as well, but the electrodes were eaten away after a couple of months.

So started studying an other solution, like a temperature sensor, it works if it's in the sump and the air temp is very different from the water temp, even if it was supposed to work with the "sudden " drop of temperature caused by the evaporation of the water film on the probe.
Still I did not like it, and Tunze has an optical sensor, IKS as well, but It gets encrusted with salt....


And then came the IDEA.......no sensor in the water, so ultrasonic rang finder ?? will work, but kind of ugly. But the one thing that worked was using a capacitive sensor, glued to the tank, outside, so no problem any more. Even if you think it will not work or get triggered by algae growing on the glass >>>> no, no effect as it triggers on sudden changes, and with 2 or 3 in line if they do not all send the same trigger >> false reading (hand, fish, snail or what ever).

I might still have the files in my old computer's HDD at home.....


Oh, did I say the sensors are small, I mean really small....like a 0.20 euro coin ?
rimai
Posts: 12881
Joined: Fri Mar 18, 2011 6:47 pm

Re: Level sensors, but not touching the water

Post by rimai »

I personally use pressure sensitive switch.
The theory is that water creates force inside a tube that opens and closes a remote switch.
No worries on snails or salt creep. It has a very close range of variance level. I think my water doesn't move more than 1/4"
A commercial sensor can be purchased here:
http://www.avastmarine.com/ssc/do/produ ... ure-Switch
Roberto.
jason
Posts: 18
Joined: Fri Apr 27, 2012 2:29 am

Re: Level sensors, but not touching the water

Post by jason »

What ???? 57 $ for a pressure sensor ????? OMG that is EXPENSIVE !!!!!!!

I used 1 as well, for controlling the water level in a huge sand decanter after a water well.

The MPX2200, cost peanuts, ok it's analog, very linear.......
And it's a differencial sensor, so it is kind compensated for atmospheric pressure changes, I just read the difference between the 2 pressures.

And I did not want that in a tank/sump as it might get clogged as well.... :)
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