Optical Auto Top Off

[jafoca]

Everybody uses float switches, and as many know they are unreliable or expensive.

I say this because they can get stuck relatively easily, and units that are redundant are expensive. Also some people who do not have the money for even basic models may use float switches wired directly into 120V AC power cords, for which they are not intended. This can be a safety hazard.

So, given that, why do not more people use optical level sensors?

Tunze uses this technology in their osmolator. I have found these sensors for a reasonable price at digi-key (23$). Here is a link to the technical spec sheet for the sensor. optical level sensor (http://www.compel.ru/images/catalog/338/Installation%20lle.pdf)

So is their any reason why this should not be used? From what I understand it would be used like a float switch, with a relay.

I am no electronics guy by any means, but I could wire it up if somebody could tell me how.

There are two hurdles I have that need to be overcome before I could work on this:
1. Circuit design - I have a friend who does E-E. Hopefully he will give me a hand.
2. Mounting - I am guessing the wire end of these sensors needs to be dry. I have some ideas on this, but other's ideas would help too.

What do you think?

[Donw]

They are more reliable than float switches. Yes the wires need to be sealed. No they dont connect just like a float switch. One wire is hot (must be regulated). One is ground. The third is the output goes to a solid state relay. Connect it to a conventional relay it will be toast in no time. The LLE series will be eaten by the saltwater and will loose its ability to refract the light.
You can have honeywell change the sensor for $5 so that it wont get eaten with a minimum purchase of 100 sensors.
The dwyer sensor is ready to go right out of the box and must be connected in the same manner.
Ive run the stock LLE series for about a month until they failed. The altered LLE for 15 months without a hitch.
The dwyer for 3 years with any problems.


Hope this helps
Don

[BruiseAndy]

From working with UV scanners and liquid level float controls on boilers my faith leans more to the float side than the optical side. Of course you should always build in a couple safeties such as high water cut offs and wet switches.

[acdraindrps]

If you don't like float switches, try using this one from champion
http://www.championlighting.com/product.php?productid=17525&cat=0&page=1

I agree that floats are unreliable. This one works on pressure to switch your pump on. A little expensive at $60