Are you familiar with frequencies? If not no worries , you will find frequencies of different kind like audible and visible world familiar to everybody. we will discuss few aspect of frequency and how to measure frequency without a multimeter?
For example, a radio station has frequency of 98.9 MHz, when ever someone will set that frequency from dial they will be able to able to receive those signal. As for as human is concerns, they cannot hear frequencies lies in electromagnetic spectrum like radio and TV frequencies. Every thing has its specific frequency from music to sound and TV, no frequency mean nothing.
What is Frequency?
Frequency is defined as
The rate at which something happens or is repeated over a specific period. The rate of frequency is hertz. Thousand hertz is called kilohertz.
When it comes to an electronic circuit the response of different component is different for different frequencies. For example the capacitor behave like open circuit at low frequencies and short circuit at high frequencies, while inductor behave like short circuit at low frequencies and open circuit at high frequency.
How to Measure Frequency without a Multimeter?
There are different methods to measure frequency. We will discuss them one by one. Let’s start
1. Frequency Meter
A frequency meter is an instrument that displays the frequency of electrical signal.
There are two types of frequency meters i.e. analog and digital. The analog meter were used in old days but after 1970s these meter are replaced by digital frequency meters.
How does a frequency meter work?
- Firstly unknown frequency signal is applied to the meter, which is then passes to amplifier which amplifies the weak signal.
- This amplified signal is now applied to Schmitt trigger which can convert input sinusoidal signal into a square wave.
- The oscillator also generates sinusoidal waves at periodic intervals of time, which is fed to Schmitt trigger.
- Schmitt trigger converts sin wave in square wave, which is in the form of continuous pulses, where one pulse is equal to one positive and one negative value of a single signal cycle.
- Square wave is given to gate control flip flop turning ON AND gate.
- The output from this AND gate count decimal value.
- For the first pulse gate will turn on, and for second pulse it will turn off.
- Similarly for third pulse it will again turn off.
- This way it continue its work.
- These continuous whose are in decimal value is displayed on the counter display.
2. Heterodyne Methods
When it come to heterodyne method of frequency measurement, you might think
What is a heterodyne frequency meter?
Heterodyne frequency meter is measuring device that contains a variable frequency oscillator (VFO), mixer, and an indicator like analog meter.
The oscillator frequency is adjusted until zero beat is reached with the signal source. This condition is shown by a dip in the meter indication. If an audio amplifier is coupled to the output of the device instead of a meter; the heterodyne appears as an audible tone whose frequency drops to zero when the oscillator frequency is equal to the signal frequency being measured.
Measure Frequency with heterodyne method
Heterodyne method is one of the best method to measure frequency with precision. In this method counter is used to measure the square wave of the beat signal. Heterodyne method is inconvenient to the multi-channel measurement and real-time display of measurement results.
3. Frequency Counter
Frequency counter is the best frequency measurement technique, But before that you might have question
What is Frequency Counter?
A frequency counter is an frequency measurement device used for measuring frequency. Frequency counters usually measure the number of cycles per second in a periodic electronic signal. Such an instrument is also called as cymometer.
Measure Frequency with Frequency Counter
- To measure the frequency of a stable repetitive signal
- Measuring the frequency of a signal on the line
- Like wise, To measure the frequency of an oscillator
- Measuring the frequency of a transmitter carrier
As we can measure the frequency of RF signal with this method but keep in mind the
- frequency should be steady
- the signal shouldn’t have modulation
- signal should have enough amplitude
- signals must not be to massive
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4. Stroboscope
Before we discuss frequency measurement technique using stroboscope first of all we will discuss
A stroboscope is frequency measurement device, that creates a stop motion effect of a rotating object by flashing a high-intensity light on it. This appearance of a moving object to be stationary can be used to study rotating, oscillating or vibrating objects. The stroboscope work on phenomenon of stroboscopic effect.
Measuring Frequency with stroboscope
Stroboscope is the another method of measuring frequency without multimeter. This is mostly used to measure the frequency, velocity, and revolutions of rotating parts or moving components.
For example when the discharge light is placed near the rotating part of machine. The part having light on it would look slow moving.
5. Counting
Another method of measuring frequency without digital multimeter is counting and measuring the frequency of a repeating event.
During this process counting is done within a particular time. we can count and divide it over period of time.
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FREQUENTLY Asked Questions (FAQS)
How do you measure frequency?
Frequency can be measured using different method
- Multimeter
- Frequency meter
- Heterodyne method
- Frequency counter
- Stroboscope
- Counting