DIY – Water Level Alarm Breadboard Prototype [Step 2]

In this tutorial we will learn about the components of the Water Level Indicator and how to successfully complete the circuit on a breadboard!

Check out the intro / final product video first. -> GO NOW

Remember, I made this device and these tutorials to help people in third world countries save water. So, for the most part I am going to be skipping the theory and background of the parts. My goal is to get the circuit working for them as quickly and easily as possible.

This is generally the first step in any circuit project, after a schematic that is, and it is testing everything on a breadboard. The breadboard doesn’t need solder which means it can be reused time and time again. It also means you can easily fix any mistakes that come about along the way.

Watch the Video Tutorial

**full article below**


I will list the part quantities as if you are going to make a two light, one buzzer alarm. However, you can duplicate the circuit as many times as you want, you will just need to add 1 resistor, 1 transistor, 1 led, and more wire.

  • 2 x bc547 transistors
  • 2 x 220 ‎Ω or 330 ‎Ω resistors
  • 2 LEDs (any colors)
  • 1 x 6v Buzzer (9v or 12v work)
  • 9v battery with applicable clip
  • 1 x on/off switch
  • wires ( a few short ones main circuit connections, 3 longer ones that will stretch from the box to where ever the water tank is. I have successfully tested the circuit over a length of 10 meters)
  • small project case

Tools (not all necessary for breadboard prototyping)

  • Soldering Iron ( 25 – 60w )
  • Solder (60 / 40 )
  • Flux
  • Damp Sponge
  • Helping Hands (third hand)
  • Breaboard
  • Wire Cutters
  • Tweezers (optional)
  • Small cup of water
  • Electrical tape
  • Hot Glue (optional)
  • Heat Shrink (optional, but recommended)

The process

The simplest way to get started is to acquire the parts and use this breadboard layout as a map.


3 LED Water Level Indicator / Alarm | Breadboard Layout

Start by connecting a resistor from any column (pad) to the power line (red line). The connect the bc547 transistor’s Collector pin to the same column as the resistor. The collector pin is the pin on the left if the flat part of the transistor is facing you.

Next connect to positive leg of an LED to the Emitter pin, which is on the opposite side. The positive lead of an LED is always going to be the longer leg, unless someone has cut it already. Then take the pad (column) that contains the negative LED leg and connect it to the common (ground) line with a small piece of wire or jumper.

Now you can connect your prob (the long wire) to the Base pin of the transistor, which is the middle pin. Put the free end of the probe into a cup of water.

Now add another probe to the power line of the breadboard and put its free end in the cup or water too. Make sure this probe will always be under the water BEFORE any other probes. I suggest tapping it to the bottom of the container.

Now you just need hook up your 9v power supply. Make sure the positive lead goes to the positive line and the negative to the negative. As soon as you make the connection you should see the LED illuminate.

Now, if you want to add a buzzer – first disconnect the battery – just add the positive lead (again the longer leg) to the same pad as the Emitter pin, and positive LED leg. Don’t forget to ground the negative leg’s pad. Then plug the battery back in. As long as both your probes are still submerged you should see the light and hear the sound.

You can duplicate this small circuit as many times as you want. Here at my house I am using a two light, 1 buzzer alarm.

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Author: Joshua Casper

Joshua Casper is an Artist, Musician, and Blogger.

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