Pulse Frequency Modulator Circuit

Introduction

A pulse frequency modulator circuit is a type of electronic device that’s used to make slight changes in the frequency of an electrical signal. It works by changing the length, or duty cycle, of each pulse so that they occur at different frequencies. This can be used to control the output voltage or current of a power supply or to send information along electronic circuits. It’s commonly used in radio and television equipment as well as computer systems and other types of electronics. Pulse frequency modulation can be seen in applications ranging from music synthesis and control systems to digital telecommunication links.

Circuit Diagram

of Pulse Frequency Modulator Circuit

More Circuit Layouts

LF357 Pin Configuration

LF357 Absolute Maximum Ratings

Working Explanation

of Pulse Frequency Modulator Circuit

The pulse width of the compact pulse/frequency modulator can be varied by altering the change-over point of comparator IC1 LF357‚ with a control voltage via resistor R1. So, the hysteresis of the IC is determined by resistors R3 and R4. The control voltage also causes the frequency of the present circuit to be altered. When the input voltage is 0 V, the frequency is a maximum: in the present design, this is about 3.8 kHz. The level of the output voltage is ±12-13 V.

The more the control voltage shifts the change-over point, the longer it takes before the potential across capacitor C1‚ has reached the level at which IC1‚ is enabled. When the managed voltage is larger than the Zener voltage, the oscillator ceases to work. The maximum period is 25 ms, which may be adapted by altering the value of C1. This will, of course, also alter the maximum frequency.

Also, the duty cycle is inversely proportional to the control voltage. So, the minimum pulse width attainable at the lowest frequency is about 6 us.

The modulator draws a current not exceeding 5 mA.

Conclusion

A Pulse Frequency Modulator (PFM) is a very versatile and useful tool that can be used in various electronic circuits to achieve varying results. Its ability to switch multiple frequencies with a single control source allows for systems to realize more accurate and efficient signal processing results than conventional analog modulation methods. Additionally, it offers low power consumption and high signal bandwidths that make it ideal for many applications such as motor control, audio signal processing, and digital filters. With its wide range of capabilities , quick response time, and improved overall accuracy compared to traditional approaches, the PFM is an important part of any modern electronics system.

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