Ever try to listen to the radio but there is a static noise making it hard to hear?
This post shows you how to build a circuit that can reduce that noise and make the radio signal clearer.
This circuit uses transistors like tiny switches to filter out the unwanted noise.
WARNING: Building electronics projects can be tricky.
Experiment under experts in electronics..
What is Noise Limiter Circuit:
An electronic circuit designed to eliminate noise peaks exceeding a predefined maximum strength in the desired input signal, thereby reducing atmospheric and other interference.
Now let us go below through the noise limiter circuit working and how the circuit is build.
Circuit Working:
Parts List:
| Category | Description | Quantity |
|---|---|---|
| Resistors | 4.7k CFR 1/4 W | 1 |
| 1MEG CFR 1/4 W | 1 | |
| Potentiometer | 10k | 2 |
| Capacitors | Electrolytic 10µF 25V | 3 |
| Semiconductors | Transistor BC547 | 1 |
| Diodes | Diodes 1N4148 | 2 |
Circuit Overview:
The circuit employs a carefully designed configuration to attenuate noise without compromising the quality of the broadcast signal.
Potentiometer R3 plays a crucial role in this process by facilitating the simultaneous transmission of both the signal and the noise to amplifier Q1.
Amplification Process:
Upon entering the circuit, both the signal and noise waveforms undergo identical amplification by transistor Q1.
The amplification ensures that the signal strength is increased making it more discernible.
However, to prevent undesirable fluctuations diodes D1 and D2 strategically limit the peak to peak output fluctuation of Q1 to approximately 1.2V
Formulas:
Formula 1:
Peak to Peak Output Fluctuation Limit:
Vpplimit = 1.2V
where,
- Voltage from Peak to Peak Vpp: The difference between a periodic waveforms maximum positive voltage Vpeak+ and minimum negative voltage Vpeak- is referred to by this phrase.
- It depicts the waveforms overall voltage swing.
- Limit (limit): The term “limit” here refers to the highest or lowest value that Vpp may be allowed.
- If this limit is exceeded, the circuit may have unfavorable effects.
- 1.2 volts is the Vpplimit: According to this formula, the circuits peak-to-peak voltage Vpp should not be more than 1.2V.
Depending on the particular use of the circuit, exceeding this limit could result in issues.
Controlled Signal Output:
By carefully adjusting potentiometer R3, the signal output can be regulated to the determined peak level.
When set appropriately, this configuration ensures that the noise peaks do not surpass the signal output.
Formula 2:
Signal Output Adjustment:
Vsignal = Vpplimit
where,
- Vpplimit: This is the voltage limit of a signal in the circuit from peak to peak, Vpp, as previously stated, is the difference between a waveforms maximum positive voltage Vpeak+ and minimum negative voltage Vpeak
- Vsignal: Under ideal conditions, this variable would indicate the signals intended or desired peak to peak voltage within the circuit.
Result:
When the signal stays within the permitted range, the formula Vsignal = Vpplimit can depict an ideal situation, otherwise, it can depict a clipping scenario in which the signal exceeds the limit.
The circuits environment and the method used to detect or calculate Vsignal will affect the actual meaning.
How to Build:
Following are the simple noise limiter circuit construction steps mentioned below:-
- Gather the required components, including resistors, transistors, diodes, and potentiometers, as per the circuit diagram.
- Begin by placing and soldering the components on a prototyping board or PCB following the schematic layout.
- Connect the input signal source to the circuit, ensuring proper grounding.
- Adjust potentiometer R3 to control the simultaneous transmission of signal and noise to amplifier Q1.
- Tune the circuit by adjusting potentiometer R3 until the signal output reaches the desired peak level of 1.2V
- Verify the effectiveness of the noise limiter by monitoring the broadcast signal quality and ensuring that noise peaks are adequately suppressed.
- Fine tune the circuit as needed to optimize performance.
Conclusion:
By following these construction details enthusiasts and engineers can successfully implement this advanced noise limiter circuit, significantly improving the audio quality of weak broadcast channels.