[Cannonball888]

If you are a tightwad like me and don't want to spend 18-20 dollars on a flood alarm then make one for less than 5 dollars and even impress yourself and your friends. It works great and screams just as well as any commercial one on the market.

How?
Go to Wallymart and buy a smoke alarm for under 5 dollars. I found one even with a battery included.

Open up the cover, but don't install the battery yet. Look at how the test button sets off the alarm. I pushes down on a metal peice to make contact with another metal peice. You need to permanently have the metal peices in contact. On my model, I was able to just tuck the first metal peice under the second one using needle-nosed pliers. You can discard the cover for this because you don't really need it.

Now for the fancy wiring. If your smoke alarm has a 9V battery terminal with wires, this part is easy, if not, you'll need to buy one from Radio Shack for under a buck, or possibly you could salvage one from an broken electronic device that used one (like an alarm clock radio). Anyway you do it, you need to interrupt the circuit of the battery by cutting into the + or - wire (doesn't matter which) and splicing each new end to a long wires respectively. The opposite ends of the long wires you will make bare at least a half-inch. This is your probe. Whether you want to attach these bare ends to finishing nails and push them into the carpet behind your tank of put then inside on the wood flooring of your tank is a matter of preference. Actually you can do both as I have done by just adding another length of wire from the first probes to make a second set of probes. Don't use finishing nails if you plan of putting probes on the wooden floor inside your stand because there is enough moisture in the wood to conduct current between the probes and make the smoke alarm emit a faint noise, but carpet is a good insulator and will work fine. For wood floors inside or outside the stand you can just tape the wires to the flooring so that the bare ends are still exposed but make contact with the flooring. Space them a 1/2-1 inch apart. Be sure that wood floorings inside or outside the stand have a protective finish because this acts like a insulator and without it the bare wood will conduct some electricity.

Although the directions may sound complicated or I'm just a bad writer, the concept is simple: You modify a smoke detector so that it is screaming constantly. You break the power loop with some wire in which the ends are used as the contacts for the probe. Any spilled water between the bare ends completes the power circuit and the alarm sounds. It works flawlessly. Tested it many times.

P.S.

If you wake up in the middle of the night to the sound of an alarm it could be your real smoke alarm and/or your flood alarm. If it's just the flood alarm then just stop the flow. If it's your real smoke alarm then call 911. If it's both, then use the spilled tank water to put the fire out

[Rp Marine]

great idea sound very nice do you have any pix? love the diy project hahahahahah

[Valclore]

Not to butt in on another project of the same type but I've had this type of flood screamer for awhile... Yours is a really good idea and hope this doesn't insult your idea??? If so I'm sorry...

[Cannonball888]

Originally Posted by Valclore

Not to butt in on another project of the same type but I've had this type of flood screamer for awhile... Yours is a really good idea and hope this doesn't insult your idea??? If so I'm sorry...

Not at all. I didn't believe I was the only one to think of it. I just noticed that no one had put the idea on the forum. Actually, yours is probably the cheapest method because all you need is the pieizo-electric screamer, battery, and wire. How much do the piezo-electric screamers cost?

[MikeTV1]

Old thread, but good info.

Based on this idea. Instead of making / breaking your battery connection and rigging the test button to constant. You could just attach your wires to the two metal pieces making the contact when the other ends of the wire are in contact with water.

This would give you the advantage of having the smoke detector functional in your stand / room as well.

[scubadude]

very good idea! Cannonball do you have pics of yours?

[MikeTV1]

I'm not sure CannonBall888 is still around. Says only the 3 posts and this was in 04'.

I will probably put one of these together this weekend and will make sure to grab pics.

[DonW]

Ive been trying to come up with a decent flood sensor for years. They always seem to be in the wrong spot so the flood has to get pretty bad before it hits the sensor.
If you install a sensor for something like your rodi holidng tank. Set the tank a little off level so that the water will always run right to the sensor.
If its for your sump you can use a level to see where the water is going to exit first. I put 4 sensors behind my last tank and flooded, of course all the water ran away from the sensors and did no good.

Don

[SouthBayPhoto]

Whooops!

[ret25yo]

so far... I have learned my lesson and will be IN FRONT of my tank when I do top offs ( i've ended up leaving top off water 2 times) i know I Need to install a float switch...
but the last time was last night about 80g on my floor.... so i'm going to ACE today to find a 9v smoke alarm.. thx...

[rjs5134]

lol, sorry to hear that, I just got home with mine.

[rjs5134]

Alright so I tried it... I'm no electrician, and this was pretty easy, however all I get is the faint chirp that signals a low battery. If I cross the wires I get the loud scream I was expecting. It leads me to believe the water is not conducting the water enough. Could it be the freshwater does not work as well as salt? I wouldn't think so. I'll post pics tomorrow.

[rjs5134]

Nevermind, made a few changes. I used 18g copper wire instead of the 9volt harness wire and I used a different smoke alarm. Now it screams beautifully, so to speak.

Thanks for the tip.

[MikeTV1]

Have my parts but have been too side tracked to get it put together.

Saltwater is more electrically conductive than freshwater however, so good to hear you have it going already, but it should have worked anyway.