Water Level Detection IC

[Guy Lavoie]

Here is something at a price that can't be beat. I just ordered 10 myself!

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...ssPageName=WD1V

If the link (which looks long) doesn't work, search for LM1830N on ebay


This might be just what I need for a pool level detection project. Could also be used for water tanks, fountains, or maybe even a water flooding detection system.

 

[electron]

Hey that looks pretty cool, much cheaper than buying a low end water sensor which isn't even this advanced! I wish PayPal wasn't the only way of paying by credit card Do you have an example how I would implement these using my SECU16? I am not too familiar yet with reading schematics. Thanks!

 

[Guy Lavoie]

I'll have to try it out with a SECU16 when I get them, but with a digital out like this chip, driving anything that accepts an open collector output like a SECU16 input should be really easy, needing just one transistor in the worse case. For a pool level application, I'd like to power it with a line-isolated wall wart and then drive an optoisolator to get the signal back to a SECU16, thus maintaining the required line isolation for anything dealing with pools.

 

[Guy Lavoie]

Here is the datasheet:

http://alldatasheet.net/datasheet-pdf/view/NSC/LM1830N.html

Looks like it has an open collector output, perfect for use with a SECU16/16I supervised input.

 

[smee]

The datasheet shows it being used with thermistors, photocells, and phototransistors too. When measuring liquid levels, it won't work with (e.g.) brake fluid or whiskey, though (conductive fluids only).

It looks like these parts were discontinued in 1998 (at least from National Semiconductor). No replacement is listed.

 

[Guy Lavoie]

I kind of laughed when I saw whiskey among the list of liquids that don't work. Looks like that question came up at some point! It also looks like this might work as a wet soil detector, which might be handy for a sprinkler control application.

I also notice that the chip seems to be designed for a 16 to 24 volt power source. This might be a bit more inconvenient then if it supported 5 or 12 volts directly, although a 12 volt transformer will a full wave rectifier and filtering capacitor will give you about 17 volts.

 

[Bruce L]

Dang you guys - I've got enough projects to play with already

I did order 10 also. They will make great water softener salt level detectors (I think). Also am gonna use one in the well house as a leak detector. If one of the pipes broke I'd never know it until the pump shorted out!

A rain detector - use a couple of bare wires on a piece of plastic - rain conects the circuit.
Ground moisture detector
Stock tank low/dry - run it offa battery and a hacked motion sensor

 

[DavidL]

BruceL, the water softner was also my first reaction looking at this thread. Were you thinking about a plastic stick running into the salt bath with electrical contacts placed at regular intervals connected to the chip? I was wondering of the longer term affect on salt on the stick and whether there would be conductivity even without the contact being immersed in the salt brine solution.

 

[electron]

I look forward to some working examples!

 

[jwilson56]

For those that might not want to hand wire IC's to get a water detector. Here is a nice one that runs off 12V.

http://www.electronickits.com/kit/complete/meas/vek2639.htm

and the diagram of the kit:

http://www.electronickits.com/kit/complete/meas/vek2639.pdf




And a cheaper model

http://www.electronickits.com/kit/complete/meas/vemk108.htm

and the diagram of the kit:

http://www.electronickits.com/kit/complete/meas/VEMK108.pdf

http://shopping.netsuite.com/s.nl?c=317485 has cheaper prices but not as many kits.

One nice thing about the kits is that you get a printed circuit so it would be easier to build and more reliable also.

John

 

[Bruce L]

DavidL:
I was thinking of a plastic tube - like fish tank tubing - with 3 or 4 probes along the way. If I read the datasheet right each probe will need it's own IC so using more than 4 isn't that usefull. Each probe will need its own wire running inside the tubing. I was thinking stainless steel hardware pushed thru a small hole in the tube then the hole sealed with RTV.

 

[DavidL]

Well I bought 20 so some one better figure out how to use the stinkers! Shipping was as much as the product...

I don't remember seeing liquid brine to the top of the salt on a consistent basis. So, wonder if conductivity will work for this implementation. I think the liquid stays fairly low in the tank and the salt only gets uncovered when the supply is real low.

 

[electron]

in my case, when the tank is low on salt, the liquid fills the tank about 1/4th, but when you fill the tank with salt, it will go up to half a tank if not more sometimes.