Simple Noise Limiter Circuit

Ever try to listen to the radio but there is a static noise making it hard to hear?

This post shows 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 dangerous.

Experiment under experts in electronics..

What is Noise Limiter Circuit:

An electrical circuit which minimizes noise levels in the set input signal and which exceeds a certain threshold to reduce atmospheric and other disturbances.

Now let us discuss about how the noise limiter circuit is built and operates.

Circuit Working:

Parts List:

Details of the Circuit:

The circuit uses a well planned setup to reduce noise without affecting the broadcast signals quality.

Because it allows the signal and noise to be delivered by amplifier Q1 at once so potentiometer R3 is essential to this method.

The Process of Amplification:

Transistor Q1 amplifies the signal and noise waveforms in the same way as they enter the circuit.

By increasing the signal power the amplification makes it easier to detect.

However diodes D1 and D2 intentionally limit the peak to peak output variation of Q1 to about 1.2V so as to avoid unwanted fluctuations.

Formulas:

Below are the formulas for Simple Noise Limiter Circuit:

Formula 1:

Peak to Peak Output Fluctuation Limit:

V_pplimit = 1.2V

where,

• The term voltage from peak to peak (Vpp) refers to the difference between the greatest positive voltage (Vpeak+) and minimum negative voltage (Vpeak-) of a periodic waveform.
• The word limit in this formula refers to the maximum or minimum value that Vpp is able to have.
• This formula states that the circuits peak-to-peak voltage (Vpp) should not exceed 1.2V which is the Vpplimit.

Depending on the circuits specific function going beyond this limit might cause problems.

Signal Output Control:

Potentiometer R3 is carefully adjusted to control the signal output at certain peak level.

This design should be properly adjusted and one should ensures that the noise peaks will not exceed the signal output.

Formula 2:

Signal Output Adjustment:

V_signal = V_pplimit

where,

• The voltage limit of a signal in the circuit from peak to peak is known as Vpplimit, the difference between a waveforms greatest positive voltage (Vpeak+) and minimum negative voltage (Vpeak) is known as Vpp.
• Vsignal is in ideal conditions this variable will reflect the circuits planned or desired signals peak-to-peak voltage.

Result:

The formula Vsignal = Vpplimit can show an ideal scenario when the signal remains within the allowed range if the signal exceeds the limit it can show a clipping situation.

The circuit environment and the method used to detect or to calculate the Vsignal will decide its real value.

How to Build:

The simple steps for building a noise limiter circuit are given below:

• As shown by the circuit design assemble the necessary parts such as resistors, transistors, diodes and potentiometers.
• Start by following the schematic layout when positioning and connecting the components on a prototype board or PCB.
• Be sure the circuit is properly grounded before connecting the input signal source.
• To regulate the simultaneous transmission of signal and noise to amplifier Q1 adjust potentiometer R3.
• Adjust potentiometer R3 to fine tune the circuit until the signal output meets the target peak level of 1.2V.
• Check if noise peaks are properly controlled by keeping an eye on the broadcast signal quality to confirm the noise limiters performance.
• Adjust the circuit as necessary to maximize efficiency.

Conclusion:

Electronic fans and engineers can properly use this clever noise limiter circuit to vastly enhance the audio quality of weak broadcast channels by following these construction instructions..

References:

Noise reduction