Everyone must be familiar with the term – Switched Mode Power Supply or SMPS. Yes, they are used in every personal computer. In fact, the Switched Mode Power Supply is widely used with many other devices. Once it is understood that what SMPS actually is, its countless applications can be easily imagined. An SMPS is used for converting the electronic power supply efficiently. Any SMPS has some storage components which store electrical energy to supply to the load device and some switching components which turn on and off at high frequencies charging and discharging the storage components.
In this tutorial, an open loop boost converter SMPS will be designed. The Boost Converter is one of the topologies of Switched Mode Power Supply (SMPS). It has a DC source as Input power like a battery, generator or rectifier. In the case of a boost converter, the output power is always greater than the input power.So, the boost converter circuit will step up the power from one DC level to a higher DC level. The method of converting one DC voltage to a different DC voltage is called DC to DC conversion. The boost converter is a DC to DC converter which steps up the input signal to the higher voltage level.
The open loop boost converter designed in the previous tutorial did not have constant and regulated voltage at the output. For a stable output, a Boost converter with error detection circuit needs to be designed. The error detection can be done by adding a feedback circuit which continuously checks the error in the output voltage and provides a regulated voltage at the output. Therefore in this tutorial, a closed loop non–isolated boost converter is designed. The boost converter can be designed in two ways- Open loop boost converter and Closed loop boost converter. In the former, there is no feedback from output to input contrary to the closed loop which has a feedback circuit. So, the output of an open loop boost converter is not regulated. In the latter, there is a feedback from the output to the input. So, the output of a closed loop boost converter is regulated.
The open loop boost converter designed in the previous tutorial had a fixed output voltage respective to the input voltage level. The output voltage of the circuit can be made variable by drawing the output through a variable resistor. The output voltage in this circuit still remains unregulated as no feedback is used.Therefore in this tutorial, an open loop non–isolated boost converter is designed. The boost converter can be designed in two ways- Open loop boost converter and closed loop boost converter. There are certain design parameters involved in the designing of the boost converter. It is important to understand these design parameters. Any boost canverter can operate in either of the two possible modes of operation.
The closed loop boost converter designed in the previous tutorial though had a constant and regulated voltage at the output but it could not be varied. For a stable output that Boost converter had an error detection circuit. The error detection was done by adding a feedback circuit which continuously checks the error in the output voltage and provided a regulated voltage at the output. For making the output of the circuit adjustable, it must be drawn through a variable resistor. This closed loop boost converter not only had a feedback circuit, its output is also adjustable. Therefore in this tutorial, a closed loop non–isolated boost converter is designed.
The designing of Boost Converter SMPS has been already discussed in the previous tutorials. In this tutorial, an open loop buck converter SMPS will be designed. The Buck Converter is also one of the topologies of the SMPS (Switched Mode Power Supply). These type of SMPS steps down the DC voltage unlike the Boost converters step up the DC voltage. So the buck Converter is also a DC to DC step down converter in which the output voltage is always less than the input voltage. Contrary to Linear Regulators which step down the DC voltage by dissipating the heat, Buck Converters step down the DC voltage through switching regulators and also step up the output current.
In the previous tutorial, fundamentals of audio filters were discussed. The audio filters can be passive or active depending upon the use of passive or active components in their designing. On the basis of frequency response, filters can be classified as high pass, low pass, band pass, Notch, band reject, T-Notch, all pass and equalizer filters. In this tutorial, an audio crossover will be designed. The Audio crossover is an electronics circuit which splits the audio signal into two or more frequency bands. These frequency bands are then, sent to the different audio drivers (Twitters, Mid Range and Woofers). A single speaker is not capable to serve the whole range of audible frequencies due to the limitations of its construction. So, different drivers (speakers) are required to deliver different range of audio frequencies.
The audio electronics is a branch of electronics that deals with designing of circuits that convert sound into electrical signals or electrical signals back into the sound. These circuits all together form an audio system. Basically, an audio system is designed to receive audio signals (via microphone), record audio in some storage, transmit audio (through wired or wireless communication channels) and reproduce audio signals (via speakers). So, the audio circuits perform signal processing for representing the sound in the form of electrical signals, manipulate the electrical (audio) signals like amplifying, filtering or mixing, reproduce sound from the audio signals, store audio into computer files or reproduce audio from an audio file. All these processes are performed by different audio related circuits or devices.
In the previous tutorial, sound wave and its properties were discussed. Now it’s time to understand Acoustic Waves. Generally, the term sound wave is used to refer the waves having frequency range audible to humans that is 20 Hz to 20 KHz. The waves having frequency greater than 20 KHz are called Ultrasonic waves and waves having a frequency range in Giga Hertz or higher are called Hypersonic Waves. The term Acoustic Wave is a more general term to refer sound or vibration of any frequency. In physics, Acoustic is the branch of science which deals with the study of any mechanical wave in the solid, liquid and gaseous medium. Acoustic Waves are longitudinal waves.
In the previous tutorials, physical properties of sound waves and acoustic waves were discussed. Sound or Acoustic Waves are in the form of vibration. Sound needs to be converted into electrical signals so that it can be processed by electronic circuits. So, the sound which is a mechanical energy must convert into electrical energy and must be precisely represented as an electrical waveform (analog) for any signal processing operations. So, there is need of a device which could sense the audio signals efficiently and convert them into electrical signals.
In the previous tutorial, working principle and classification of microphones was discussed. The microphone is an input transducer which converts sound waves into electrical signals. The audio signals from a MIC are amplified by a preamplifier and transferred to the main audio unit. The audio unit might comprise of amplifier and/or filter circuit or may have other circuitry to store audio to a computer. The amplified or stored audio is reproduced using another type of transducer which is called speaker. The Speaker is a type of output transducer which converts the electrical signal into audio signal. Speakers are enclosed in a rectangular or square shape cabinet. The shape of the box affects the quality of the sound. The cabinet consists of different types of transducers/speakers which produce different types of audio frequency. Each transducer is called as ‘driver’ and the whole cabinet is known as ‘loudspeaker’.
In the previous tutorials, two of the most important building blocks of an audio system – Microphone and Speaker were discussed. An audio system is designed to receive audio signals (via microphone), record audio in some storage, transmit audio (through wired or wireless communication channels) and reproduce audio signals (via speakers).
Audio is one of the most common media. Here, It refers to the representation of sound which can be perceived by humans. Audio and Video are the essential component of any electronic media. The electronics can be used to receive audio signals (via microphone), record audio in some storage, transmit audio (through wired or wireless communication channels) and reproduce audio signals (via speakers). The audio can be represented and transmitted as either analog signals or digital signals. In this series, analog audio signals are the concern. The audio signals have a frequency range of 20 Hz to 20,000 Hz.
Lithium-ion batteries are another popular type of batteries that are used in the Uninterruptible Power Supply (UPS) designs. These batteries are commonly used in portable electronic devices. These are low maintenance batteries having high energy density, small size and light weight which makes them suitable for use in most of the portable devices. But, due to high energy density in comparison to the weight and volume of the Li-ion Battery, there are also some safety concerns while charging the Li-ion batteries. Before designing a charger circuit for these batteries, let us first understand charging methods and topologies involved in charging Li-ion batteries. Also, precautions required in handling, storing and disposing of these batteries are must to know.
The Uninterruptible Power Supply (UPS) is an electronics device which supplies power to a load when main supplies or input power source fails. It not only acts as an emergency power source for the appliances, it serves to resolve common power problems too. Any UPS has a power storage element which stores energy in the form of chemical energy like the energy is stored in batteries.It is like energy is stored in the form of motion in a flywheel. That is why these devices are also called battery backup or flywheel backup. The UPS not only provides emergency power, they also help to sort out common power related issues like providing protection from input power interruptions, protection from overvoltage, output voltage regulation and stabilization.
LM317 is commonly used for voltage regulation in DC circuits. The IC is one of the popular adjustable positive voltage regulators that comes with features like over voltage protection, internal current limiting, overload protection, low quiescent current (for more stable output) and safe area compensation (its internal circuitry limit the maximum power dissipation so it does not self-destruct). Apart from many features, less number of components are required to make it operational. So, LM317 regulator is easy to use and assemble in a circuit. In this project, an adjustable power supply using LM317 is designed which inputs main AC supplies (220V-230V AC) and outputs DC voltage below 12V. The LM317 has an adjustable output voltage of 1.28 V to 11 V and draws maximum 1.5 A current.
In the previous tutorial, an audio crossover was designed using high pass and low pass audio filter. In this tutorial, an audio equalizer will be designed. An Equalizer (abbreviated as EQ) is an audio equipment which cut or boosts the certain frequency components from the audio signal. This process of adjusting the frequency components is called as Equalization.The equalizers are widely used in the audio systems during recording of sound as well as in amplifiers and mixers. As they are used in the audio system so are called Audio Equalizer.
In the previous tutorial, an audio equalizer was designed. In this tutorial, now an audio mixer will be designed. The Audio Mixer is an electronic device which combines and modifies the audio signals. The audio signals can be either in digital form or analog form. In digital form, the analog audio signals are encoded so that the audio information in the signal becomes independent of the amplitude of the signal. Both analog and digital signals can be combined by different types of audio mixers. For mixing digital audio signals, digital signal processing techniques are used while for combining the analog audio signals, generally operational amplifiers are used.
In all the previous tutorial, a pre amplifier using MAX4468 was designed. On the basis of application, there are two types of audio amplifiers – 1) Pre-Amplifier2) Power Amplifier The pre-amplifiers are used to level up the audio signals from a microphone or audio source to standard voltage levels while the power amplifiers are generally used at the output stage of the audio systems to boost audio signals before they are reproduced by the speakers. As the name suggests, a Pre- amplifier prepares the signal which is coming from the microphone or line input for further processing and transmission of the signal. A preamp is the hidden part of any device. It is integrated in the USB microphones, sound cards and mixers.
In all the previous tutorials, power amplifiers were designed. On the basis of application, there are two types of audio amplifiers – 1) Pre-Amplifier2) Power Amplifier The pre-amplifiers are used to level up the audio signals from a microphone or audio source to standard voltage levels while the power amplifiers are generally used at the output stage of the audio systems to boost audio signals before they are reproduced by the speakers. As the name suggests, a Pre- amplifier prepares the signal which is coming from the microphone or line input for further processing and transmission of the signal. A preamp is the hidden part of any device. It is integrated in the USB microphones, sound cards and mixers.