This circuit teaches how much level of water is in a tank.
It beeps like an alarm when the water level gets too high or too low.
We will build one using transistors electronic parts that will only beep when there is water between two metal sensors placed inside the tank.
This post will show how to make this circuit including all the details what is good about it and what is not so good.
Circuit Working:
Parts List:
| Components | Value | QTY |
| Transistors | BC547, BC557 | 1 each |
| Resistor | 10Ω, 1/4 watt | 1 |
| Speaker | 8Ω | 1 |
| Power Source | +3V to 6V | 1 |
| Water level probes | Any Metal probes | 2 |
Let us begin by understanding the connections and components used in this circuit:
BC547 Transistor:
The +3V power source is connected to emitter of the BC547 transistor .
The collector C of the BC557 transistor is connected to the base of the BC547 transistor.
BC557 Transistor:
Collector C of the BC557 transistor is connected to the ground through a 10 ohm resistor.
Speaker:
The 8 ohm speaker is connected between the emitter of the BC547 transistor and the ground 0V supply.
Water Level Probes:
The probes for measuring water levels are the BC547 transistors base and the +3V power supply.
Formulas:
To build a water level indication buzzer circuit one may use the basic circuit design along with the below mentioned formula:
Calculating the BC557 Base Resistor:
The BC557 transistors base resistor is often made to limit the base current to a safe level so as to ensure its proper functioning and to protect the transistor.
R1 = VCC − VBE / IB
where,
- The supply voltage 3V is VCC.
- The base emitter voltage drop of the BC557 transistor is represented by VBE which is usually 0.7V.
- Based on the intended collector current and the transistors current gain.
- IB is the base current needed for the transistor to operate properly.
Speaker Limiting Resistor for Current:
A resistor controls the amount of current that passes through the speaker so as to protect the transistor BC547 and the speaker itself.
R2 = VCC / Ispeaker
where,
- The supplied voltage is VCC is 3V.
- The speakers current rating Ispeaker is between 20 and 30 mA for tiny speakers.
These formula provide the essential basis for constructing the circuit.
Real resistor values and transistor properties can differ depending on specific component datasheets and the expected circuit performance.
Perform any required corrections after doing actual testing to confirm everything.
Working of the Circuit:
The BC547 transistor is used as a switch to control the flow of current in the circuit.
When no water is detected between the probes the base of the BC547 transistor is not conducting and the transistor remains in the off state.
The BC557 transistor acts as a voltage divider with the 10 ohm resistor.
It is connected to the ground and provides a path for current to flow when water is detected between the probes.
The 8 ohm speaker is connected between the emitter of the BC547 transistor and the ground.
When water comes into contact with the probes, it completes the circuit allowing current to flow through the BC547 transistor which then activates the speaker.
Advantages:
- Simple and cost effective design.
- Low power consumption.
- Audible alert when water is detected.
Disadvantages:
- Limited sensitivity and accuracy.
- Requires manual monitoring.
How to Build:
- Gather all the components mentioned above.
- Place the BC547 and BC557 transistors on the PCB.
- Connect the emitter of the BC547 transistor to the +3V power source.
- Join the base of the BC547 transistor to the collector of the BC557 transistor.
- Connect the collector of the BC557 transistor to the ground line using a 10 ohm resistor.
- Attach the 8 ohm speaker between the emitter of the BC547 transistor and the ground.
- Use the +3V power source and the base of the BC547 transistor as water level probes.
Note:
Check that there are no loose connections and that the circuit is properly connected.
Conclusion:
A simple way to measure water levels in several kinds of applications is presented by the water level indicator buzzer circuit.
If users understand the connections and function of each component than thy can successfully construct and carry out this circuit for its their own needs.