555 water level alarm

thatoneguy

Joined Feb 19, 2009
6,359
Not very loud, and not for very long, as the wires will become anode and cathode, increasing their resistance.

If the ater is pure or deionized, it won't work at all.

What 'grade' of water are you trying to get the level of?

Sometimes an ultrasonic rangefinder works best, when looking down.

Other times, "normal" water will close contacts similar to the one above to turn on an alarm or bilge pump.

Click "Search" in the userbar at top and type in "water level" to find many solutions that have been in use and work well.
 
The problem with this cct is the load current must flow through the probes and water, so the resistance must be very low
it is better to put the probes between the reset pin 4 and GND and use the 7555 CMOS version
Another idea to connect the probes between threshold pin 5 and VCC so the sound (frequency) will vary as water builds up
 

Thread Starter

@android

Joined Dec 15, 2011
178
I'm not gonna use this for pure water. This is for normal tap water. Will 6V suffice current requirements? Because water will offer much resistance. Right?
 
well, tab water differ from town to town and country to country, if the probes are large enough, they will be ok, but remember what thatoneguy said about ionization, the more current the quicker things go bad unless you use stainless steel or Carbon rods or anything that will not react chemically
 

Thread Starter

@android

Joined Dec 15, 2011
178
well, tab water differ from town to town and country to country, if the probes are large enough, they will be ok, but remember what thatoneguy said about ionization, the more current the quicker things go bad unless you use stainless steel or Carbon rods or anything that will not react chemically
Large probes? Means how big?
 

Thread Starter

@android

Joined Dec 15, 2011
178
Most probably, I'm looking forward to implement similar kind of design. Anything to improve reliability will help. But the basic question remains....'will this work correctly?'
 

KMoffett

Joined Dec 19, 2007
2,902
A small modification for your alarm pulser. This works. Don't worry to much about the electrodes corroding due to electrolysis . They will only be in the water on the rare occasion of an alarm condition. I would still opt for stainless steel if continually exposed to humid conditions above a water surface.

Are you intending this to be battery operated, or DC from a wall-wart?

Ken
 

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thatoneguy

Joined Feb 19, 2009
6,359
Ask for stainless steel TIG rods at the welding store. Or just go to your hardware store and buy a small spool of ~20 gauge stainless steel wire.

Ken
That too. Remember to use alligator clips, as SS isn't really friendly to soldering with copper, and they need replacement once in a while anyway.
 

KMoffett

Joined Dec 19, 2007
2,902
I usually tin the end of the SS rod with a silver braze/solder. That way you can then soft solder (tin/lead) copper wire directly to it.

Ken
 
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