Electronic Water Tag Game




About: My name is Jason Poel Smith. In my free time, I am an Inventor, Maker, Hacker, Tinker, and all around Mad Genius

Everyone loves water gun fights in the summer. But you can always make something better by adding electronics to it. So I designed a set of water sensors and buzzers that will beep when they are hit with the spray of a water gun. This lets you play a game similar to laser tag but with water.

And if you want wondering, no it won't shock you or electrocute you. The circuit is well sealed in its housing and the amount of electricity that we are working with is so small that it couldn't shock you anyway.

Step 1: Watch the Video

Here is a video walkthrough of the project.

Step 2: Materials

Here are the material and tools that you will need for this project.


555 Timer IC

Perf Board

Piezo Buzzer

1 Mohm Resistor

100 kohm Resistor

1 kohm Resistor

10 Microfarad Capacitor

Paper Clips

Jumper Wires

Binder Clamp

3 AAA Batteries

Battery Holder for 3 AAA Batteries

Spray-on Sealer or Paint

Water Guns


Soldering Iron and Solder

Hot Glue Gun



Wire Strippers

Step 3: The Control Circuit

Here is the circuit that I designed for this project. It is a slightly modified version of a 555 timer circuit in monostable mode. Here is how it works.

The output of the circuit is controlled by the voltages at pins 2 and 6. The resistors that are connected to these two pins set the initial voltage HIGH (roughly the same as the supply voltage). When water sprays the connectors between pin 2 and ground, the voltage at pin 2 drops below the reference threshold (1/3 of the supply voltage). This causes the output at pin 3 to go HIGH and turns on the buzzer for a few seconds. How long the buzzer will remain on is determined by the values of the capacitor and the resistors connected to pin 6. With the values that I used (shown in the circuit diagram), the buzzer will sound for about 2 seconds. Increasing the values of the resistor or the capacitor will increase this time. Decreasing these values will decrease this time.

So basically, when water is sprayed on the sensor, the circuit beeps for a few seconds.

Step 4: Water Sensor Design

The kind of water sensor that I chose to use in this project is just a series of wires running parallel to each other. When a drop of water hits two adjacent wires it conducts electricity between them and triggers the control circuit. The wires that I used for this are made from paperclips. I chose these because they are relatively sturdy and will hold their shape.

First, take the paperclips and unfold them so that they are straight. Then decide on how you want the sensor to set up. For prototyping, I just took the whole wires and bent them into a "U" and stuck them in adjacent slots on a breadboard. For the final configuration, I bent them into smaller U's with sharp angles similar to staples. Then I soldered them to a piece of perf board.

Step 5: Prototype Everything on Breadboards

It is always a good idea to prototype the circuit on a breadboard before soldering a circuit together. This will give you a change to test it out and make any necessary changes.

Step 6: Solder the Circuit Onto a Piece of Perf Board

Once you are satisfied with how the system is performing, you are ready to solder everything together. I soldered my circuit onto a piece of perf board. I like to use perf boards when soldering together prototypes because they are very versatile and let you make connections in any way that you want.

Step 7: Seal the Board of the Water Sensor

There are a lot of exposed wires on the water sensor. If a drop of water connects any of them the buzzer will sound. If a drop of water gets stuck between them, then the buzzer will stay on and be really annoying. So to help prevent this, I sealed most of the board to insulate it.

First I taped over the portion of the sensor that I want to remain exposed. This was the top face of the wires sticking out of the board. Then you can use any kind of spray on sealer or spray paint to coat the rest of the board. Be sure to get thorough coverage. You want to cover up all the exposed metal.

Once it has completely dried, check to see if it needs another coat. Once you are satisfied with the coverage, remove the tape.

Step 8: Mount Everything Inside a Project Enclosure

Now all you have to do is mount all the parts inside a project enclosure. You need to make one hole in the top of the enclosure for the buzzer. You also need to cut a slot in the side of the housing for the wires that go to the water sensor.

I attached the circuit to the inside of the housing with hot glue. I also mounted the batteries inside the box. Then I closed it up and screwed on the lid.

Step 9: Finished Water Tag System

Now your water tag system is complete and ready to try out.

There are a lot of ways that you can use this system. The simplest way is to just put the control circuit inside your pocket and attach the sensor to your clothes. You can do this with a safety pin, a binder clamp or a fabric arm band. I just glued a binder clamp to the back of the board and clipped it on my shirt. You can also set up the sensor on a stationary platform like a target shooting game.

At times the buzzer might stay on after being activated. This means that a bead of water is stuck between wires on the sensor. To fix this just brush it with your hand or blow on it. This should knock off the offending drop of water and allow the system to reset.

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Participated in the
Unusual Uses Challenge

Outside Contest

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Outside Contest



    • Classroom Science Contest

      Classroom Science Contest
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      1 Hour Challenge
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      Frozen Treats Challenge

    26 Discussions


    2 years ago

    Awesome. it's like laser tag with water guns. Great idea, thanks for sharing!

    You have to create the connections. You can do this by bending the ends of the leads over so that they reach the next connection terminal. Or you can make a large drop of solder and use your soldering iron to drag it across two adjacent terminals so that they are connected.


    3 years ago on Introduction

    Why do you really need the timing chip? Can't you just build this setup using just some wires, batteries and a capacitor?

    1 reply

    3 years ago on Introduction

    I can't seem to get it to work. I got all the components exactly as listed but piezo makes noise when there is no contact and as soon as contact is made between pin 2 and ground, the noise stops. Has anyone got an idea on why that occurs?

    4 replies

    So it is doing the opposite of what it should? That could happen if the buzzer where wired to positive instead of ground. It would help if you could post a picture of both sides of the board.

    Thanks for the suggestion. In the mean time I have been experimenting with the circuit and I noticed that if I replaced the piezo with a LED, it works perfectly. Does it have to be a specific kind of piezo? I got a KPM-1205A.

    It's been a while since my last comment but I was waiting for some new buzzers and with these it works perfectly! Very loud :) The only thing that's left is mounting it all inside the enclosure. Thanks for the help and the great project. I've already learned a lot.


    4 years ago

    I know it says it won't shock you but in reality no matter how much voltage you're dealing with if there is water lands on the circuits you'll be shocked

    1 reply

    Most people can't feel currents less than 5mA. That is hundred of times more current than this circuit could deliver to your skin.


    4 years ago

    What happens when water gets on the circuts