Water Level Indicator with Auto AC Switch control

The water level indicator circuit is very basic but effective control circuit.

First I will walk you through all the mini components required to build this circuit later provide you a working PCB layout.

These are two basic fundamental digital electronics circuits I used to build this complete circuit.

1. Buffer Gate/Amplifier

2. SR Latch
3. Diagram
4. Schematic

Let's try to understand these two first so it will be very easy two understand the rest of complete circuit.

Buffer Gate/Amplifier:

A buffer Gate or amplifier required very low current as an Input and provide a high current as an output. Later the output can be used to light a LED or as an Input for another circuit. You can explore how Buffer gate and Not Gate works on my Youtube channel.

In our case we provide Input from water contact.

We all know pure water is bad conductor of electricity but we just need very low input and this will be sufficient for our purpose.

SR Latch:

SR latch is the basic building block of the memory element in digital electronics.

A simple SR can store 1 bit of memory (you can call 1bit RAM). In our project we need to store the information that our Water Tank is full or Empty.

I have used a NOR Gate based SR Latch in this project. NOR is when we invert output of OR Gate. You can explore complete NOR Gate working here on my Youtube channel.

In case of water level indicator project Set and Reset is done Tank is empty and Tank is full.

Diagram: 

Below is the complete circuit diagram at high level. There 5 levels from Water Level Tank which is constructed with Buffer Gate. (see: buffer gate above)

Level Inputs

Level inputs are provided from water level from water tank. There is a common 5v supply in water tank. When water rise to level this water make contact between two nodes and a low current is flown in level circuit.

Schematic:

This is the circuit, I came up with based on above diagram. All Gate are constructed using BC547 transistor even the basic Buffer Gate, Not Gate and SR Latch. you can use IC(Integrated Circuit) if don't want to use the many of transistors.

Please comment below if have any query related above project.

Thanks