Instructables
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12v water sensor.bmp
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I will Teach you how to make a simple water sensor circuit
 
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Step 1: Gather Parts

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Parts List
1 General Purpose NPN Transistor $0.10
1 50K Trimpot $0.15
1 47ohm Resistor $0.01
1 LED $0.08
1 Proto Board or You can etch A PCB
1 3 volt power source battery, wall wart, whatever

Step 2: Learn the Layout

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12v water sensor.bmp
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Read Circuit Diagram

Step 3: Create PCB (skip step if using Proto board)

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The Schematic is made with ExpressPCB which is a free PCB Layout Software you can download it here
Than Download the PCB file and open and print it and make your PCB. Here are a few links to Instructibles that show you how to make a PCB
water sensor.pcb is 3v
water sensor2.pcb is 12v
5pcb
Cheap and Easy Toner Transfer for PCB Making
The Saltwater etch process

Step 4: Build It

Build time will update once I make the PCB

Step 5: Connect to HHO Cell or Any other Water Sening Probe

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Here are some mock ups of how to connect it to a HHO Cell or just detect water.

Step 6: 12 VOLT CIRCUIT

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Here is how to setup the circuit to run on 12 volts from a car battery the circuit is still the same just some resistors are added to the probes to protect the transistor and a larger resistor to protect the LED
eng_tako3 years ago
thank you very much you help me alot
Assuming clean water, zero turbulence, very small inflow related to volume, could I get 1/32 inch level gage accuracy? In other words, under perfect conditions, what accuracy could one expect?
Zhelnot4 years ago
are you done with this thing??
geniusgippy4 years ago
can nybody eloborate on which HHO cell to use!!!
jpsailr4 years ago
After many attempts to make a circuit like this, I gave up. Reason: when current flows through water from one plate to another, gas builds up on the sensor plates and the conductivity of the water reduces until it is undetectable, over 10 megohms within minutes. So if you're not there right when it happens, you will miss it. I solved this by creating a circuit which would put an AC current on the sensor plates. This continually purges the plates of gas and keeps the resistance through the water to less than 100 Kohms - very useable. This test ran for over 4 hours with no loss of conductivity. Now I successfully use it to detect bilge water as soon as it happens, or water on the basement floor. I will submit a project when I get it written up.
mathew0865 years ago
Hey... I find this one soo interesting n simple that i am planning to try oit put once. but i have a small question? How much current does the circuit consume for one time function. meaning if the circuit detects water how much currents is consumed by the circuit from the 12 V battery??? thanksss
That's pretty easy to figure out with Ohm's Law. There are two paths that current will take through the circuit: the first is through the LED and into the collector of the transistor, and the second is through the probes, the water itself, and the 22K resistor. The current through the LED part of the circuit will be about 36mA, and assuming the water has perfect conductivity (it definitely doesn't, but that's a worst-case scenario) the current through the probes will be under 1mA. In other words, trivial.