Vibrating reed Frequency Meter types, Working, Construction, Range, Advantages, Disadvantages

Vibrating-reed Frequency Meter

A vibrating-reed frequency meter is a measuring instrument that is used to measure the frequency of various electric circuits. It consists of 7 vibrating reeds and each vibrating reed has a specific value. These reeds vibrate when this frequency meter is connected to the supply for the measurement of frequency. A reed that vibrates more as compared to the other reeds, the more vibrating reed is considered as frequency reading of a supply or electric circuit.

Construction

This frequency meter consists of thin flat steel reeds which are arranged alongside and these reeds are near to the electromagnet. The electromagnet consists of a laminated armature and a winding connected with a resistance in series on it. This winding is connected to the AC supply whose frequency is to be measured. The metallic reeds are 4mm wide and 0.5 mm thick. These metallic reeds are arranged in a row and consist of flexible bases and these bases carry the armature of the electromagnet. These reeds are colored with white color. These reeds are arranged in ascending order of frequency on a scale.

Range

These vibrating reed frequency meters consist of small readings from 47 Hz to 53 Hz and 57 Hz to 63 Hz.

Working of Vibrating-reed Frequency Meter

To measure the frequency of the circuit, it is compulsory to connect the frequency meter to a supply. The electromagnet is connected to the supply for which frequency is to be measured. The magnetism of the electromagnet alternates with the same frequency and the electro-magnet exerts the attracting force on each reed once every half cycle. All reeds start vibrating but the reed whose frequency is double, vibrates with maximum amplitude due to mechanical resonance. The vibration of the other reeds is so small and these are unobservable.

Types Of Frequency Meter

Frequency meters are instruments used to measure the frequency of an electrical signal, which is the number of cycles or oscillations that occur in one second. There are several types of frequency meters designed for different applications and levels of accuracy. Here are some common types:

1. Analog Frequency Meters:

• Moving Iron Instruments: These meters use the deflection of a moving iron vane in response to the applied frequency. They are simple and suitable for lower-frequency measurements.
• Moving Coil Meters: Similar to moving iron instruments, these meters use a moving coil and magnetic field to measure frequency. They offer good accuracy and are used in many applications.

1. Digital Frequency Meters:

• Digital frequency meters use digital technology to directly measure and display frequency. They are highly accurate and offer features like easy readability and precise measurements.
• Frequency Counters: These are specialized digital frequency meters that count the number of cycles within a predefined time period to determine frequency. They are commonly used in laboratories and electronics testing.
• Microcontroller-Based Frequency Meters: These meters use microcontrollers to measure and display frequency. They are versatile and often include additional features like waveform analysis.

1. Resonant Frequency Meters:

• Resonant frequency meters use the resonance phenomenon to measure frequency. One common type is the resonance bridge, which adjusts the frequency of an oscillator circuit until it resonates with the input signal. The resonant frequency is then measured and displayed.

1. Mechanical Frequency Meters:

• Taut Band Meters: These meters use a taut band suspension system to measure frequency. They are rugged and suitable for harsh environments.
• Reed Frequency Meters: Reed-type frequency meters use the vibration of reeds or strips to respond to the applied frequency. They are often used in portable equipment.

1. Optical Frequency Meters:

• Optical frequency meters use principles of optics to measure frequency, such as interferometry or laser locking techniques. They are highly accurate and used in advanced scientific applications.

1. Electromagnetic Frequency Meters:

• These meters use electromagnetic principles, such as the Faraday effect or electromagnetic resonance, to measure frequency. They are used in specialized applications.

1. Software-Based Frequency Meters:

• Frequency measurement can also be performed using software-based methods, such as Fast Fourier Transform (FFT) algorithms. These methods are common in software-defined radio (SDR) and signal analysis applications.

Advantages

Its indications are independent.

Its readings are reliable.

These are cheap.

Disadvantages

The reading is not be observed properly if the frequency difference is half cycle between the adjacent reeds.

These instruments are not accurate to provide the exact reading on its scale.