This document provides an overview of basic relay driving circuits. It discusses how relays require a minimum current to activate their coils and stay energized. Simple circuits are presented using transistors or a 555 timer IC to allow low-power control of relays with higher current coils. The 555 IC circuit requires less input current than transistor circuits. Diodes are recommended to protect components from voltage spikes when relays deactivate.
There are several types of power supplies that can be used for electronic circuits. A basic power supply consists of a transformer, rectifier, and smoothing capacitor. More advanced supplies also include a voltage regulator. The transformer steps down the high voltage mains power. The rectifier converts AC to DC. Smoothing reduces voltage fluctuations. Regulators ensure a constant output voltage. Some circuits require a dual supply with both positive and negative outputs.
The document discusses voltage regulators and digital to analog converters (DACs). It provides details on:
1) How voltage regulators work to keep an output voltage constant by sensing changes and amplifying any difference between the output and a reference voltage.
2) Common types of voltage regulators including fixed voltage 78XX series and adjustable voltage 723 series.
3) Types of DACs including weighted resistor, R-2R ladder, and inverted R-2R ladder; and how their resistor networks convert a digital input to an analog output voltage.
4) How successive approximation and dual slope ADCs work to convert an analog input to digital output using comparison and feedback to approximate or time the input voltage.
Water level indicator with alarm for underground tank Adad Med Chérif
This device is designed to
indicate the level of water in the underground tank and produces the sound when the sensor detects the presence of a water at different levels. This enables the occupant of the house to take the necessary precautions to eliminate the wasting of water .
THIS IS COMPELTE VARIABLE POWER SUPPLY PROJECT, HELP YOU YOU TO UNDERSTAND. WE DESIGNED THE CIRCUIT ON PROTEUS AND ITS PICTURE IS IN PROTEUS.IT WILL GIVE YOU BOTH POSITIVE AND NEGATIVE VOLTAGE.
The document discusses oscillators and feedback amplifiers. It defines positive and negative feedback, and describes their effects on gain. Oscillators generate an output signal without an external input through the use of positive feedback in an amplifier circuit. The two main types of oscillators are sinusoidal and non-sinusoidal oscillators. Common oscillator circuits discussed include the RC phase shift oscillator, Hartley oscillator, and common emitter amplifier configuration.
This document contains a lab manual for experiments in electronic circuit design using mechatronics engineering. It includes 10 listed experiments involving various components like SCRs, DIACs, TRIACs, op-amps, and filters. Experiment 1 details obtaining the V-I characteristics of an SCR to find the break over voltage and holding current. Experiment 4 involves designing inverting and non-inverting amplifiers using op-amps. Experiment 8 analyzes the effect of varying frequency on the output voltage of low-pass and high-pass filters.
The document discusses various timer circuits using the 555 and 556 timer ICs. It provides details on:
- The 555 and 556 timer ICs, including pinouts, power supply requirements, and output capabilities.
- Common timer circuits like astable (oscillator), monostable (one-shot), and bistable (flip-flop). Formulas for calculating timing periods are given.
- Example applications like producing audio tones, flashing LEDs, and creating timing pulses for other circuits.
- Additional topics covered include duty cycle adjustment, power-on triggering, edge triggering, and protecting outputs driving inductive loads.
There are several types of power supplies that can be used for electronic circuits. A basic power supply consists of a transformer, rectifier, and smoothing capacitor. More advanced supplies also include a voltage regulator. The transformer steps down the high voltage mains power. The rectifier converts AC to DC. Smoothing reduces voltage fluctuations. Regulators ensure a constant output voltage. Some circuits require a dual supply with both positive and negative outputs.
The document discusses voltage regulators and digital to analog converters (DACs). It provides details on:
1) How voltage regulators work to keep an output voltage constant by sensing changes and amplifying any difference between the output and a reference voltage.
2) Common types of voltage regulators including fixed voltage 78XX series and adjustable voltage 723 series.
3) Types of DACs including weighted resistor, R-2R ladder, and inverted R-2R ladder; and how their resistor networks convert a digital input to an analog output voltage.
4) How successive approximation and dual slope ADCs work to convert an analog input to digital output using comparison and feedback to approximate or time the input voltage.
Water level indicator with alarm for underground tank Adad Med Chérif
This device is designed to
indicate the level of water in the underground tank and produces the sound when the sensor detects the presence of a water at different levels. This enables the occupant of the house to take the necessary precautions to eliminate the wasting of water .
THIS IS COMPELTE VARIABLE POWER SUPPLY PROJECT, HELP YOU YOU TO UNDERSTAND. WE DESIGNED THE CIRCUIT ON PROTEUS AND ITS PICTURE IS IN PROTEUS.IT WILL GIVE YOU BOTH POSITIVE AND NEGATIVE VOLTAGE.
The document discusses oscillators and feedback amplifiers. It defines positive and negative feedback, and describes their effects on gain. Oscillators generate an output signal without an external input through the use of positive feedback in an amplifier circuit. The two main types of oscillators are sinusoidal and non-sinusoidal oscillators. Common oscillator circuits discussed include the RC phase shift oscillator, Hartley oscillator, and common emitter amplifier configuration.
This document contains a lab manual for experiments in electronic circuit design using mechatronics engineering. It includes 10 listed experiments involving various components like SCRs, DIACs, TRIACs, op-amps, and filters. Experiment 1 details obtaining the V-I characteristics of an SCR to find the break over voltage and holding current. Experiment 4 involves designing inverting and non-inverting amplifiers using op-amps. Experiment 8 analyzes the effect of varying frequency on the output voltage of low-pass and high-pass filters.
The document discusses various timer circuits using the 555 and 556 timer ICs. It provides details on:
- The 555 and 556 timer ICs, including pinouts, power supply requirements, and output capabilities.
- Common timer circuits like astable (oscillator), monostable (one-shot), and bistable (flip-flop). Formulas for calculating timing periods are given.
- Example applications like producing audio tones, flashing LEDs, and creating timing pulses for other circuits.
- Additional topics covered include duty cycle adjustment, power-on triggering, edge triggering, and protecting outputs driving inductive loads.
The document discusses operational amplifiers (op-amps) and their use in integrator and differentiator circuits. It defines an op-amp as an integrated circuit that amplifies input signals through high gain. An integrator circuit uses an op-amp with a capacitor in feedback, resulting in an output voltage that is inversely proportional to time. A differentiator circuit contains a capacitor in the signal path, producing an output equal to the derivative of the input voltage. Practical implementations of these circuits are also described, along with their applications in areas like analog computing and signal processing.
The document describes a multiple output power supply design for a DVD player with the following key points:
1. It provides 7.5W of continuous output power and 13W of peak power with outputs of 3.3V, 5V, 12V, and -12V regulated using a TinySwitch-PK controller in a flyback topology.
2. It achieves good cross-regulation between the 5V and 3.3V outputs through minimizing leakage and sum regulating the feedback.
3. It includes features for EMI filtering, surge protection, clamping, and a unique peak mode for boosting current limit during peaks loads.
This document describes an anti-bag snatching alarm circuit designed to prevent theft. The circuit uses an operational amplifier configured as a comparator to detect when a mono plug is detached from the circuit, activating a timer and alarm tone generator. A transistor amplifies the alarm tone to a loudspeaker. It operates on a 9V battery and produces a loud siren noise to draw attention if anyone attempts to snatch the bag containing the circuit. The document provides details on the components, working principle, applications and advantages of using this simple, low-cost anti-theft alarm system.
Oscillators convert DC to AC signals using a feedback loop that sustains oscillations. Common oscillator circuits include LC, RC, quartz, and relaxation oscillators. The Hartley oscillator uses a tapped coil and capacitor in a feedback loop to generate radio frequencies. The Colpitts oscillator also uses an LC tank circuit but with capacitors in the feedback path. The Franklin oscillator uses two transistors and an LC circuit, with each transistor inverting the phase to sustain oscillations. The Wein bridge oscillator is an RC circuit that produces sine waves with high quality resonance and tuning capabilities. Oscillators are used to generate signals for applications like radio transmission, testing equipment, and sensors.
This document provides an overview of the 555 and 556 timer integrated circuits (ICs). It describes their pinouts, operating voltages, output capabilities, and common circuit configurations including astable (oscillator), monostable (one-shot), and bistable modes. Example circuits and applications are given for each mode to generate square waves, timed pulses, and simple memory functions. Guidelines for selecting component values to achieve desired timing are also provided.
This document summarizes power semiconductor switches, including diodes, thyristors, bipolar junction transistors (BJTs), metal-oxide-semiconductor field-effect transistors (MOSFETs), insulated-gate bipolar transistors (IGBTs), gate turn-off thyristors (GTOs), and other developing switching devices. It describes the characteristics, features, and operating principles of these different types of switches through diagrams, images, and brief explanations.
The document describes the steps to create a 15V DC power supply. It includes circuit designing, simulation, component purchasing, breadboard testing, and PCB design using Altium. Key steps are transforming AC to DC using a rectifier and filter, regulating the voltage to 15V using LM7815 and LM7915 regulators, and verifying the circuit works by lighting LEDs and measuring output on a CRO. The PCB is created by printing the design on a copper board, etching away extra copper, drilling holes, soldering components, and testing the finished board.
Variable Power Supply with Digital Control with seven segments display is one of the applications of electronics to increase the facilities of life. It is facilitates the operation of voltage regulators around the electronics lab. It provides a system that is simple to understand and also to operate, a system that would be cheaper and affordable.
A New Active Snubber Circuit for PFC ConverterIDES Editor
In this paper, a new active snubber circuit is
developed for PFC converter. This active snubber circuit
provides zero voltage transition (ZVT) turn on and zero
current transition (ZCT) turn off for the main switch
without any extra current or voltage stresses. Auxiliary
switch turns on and off with zero current switching (ZCS)
without voltage stress. Although there is a current stress
on the auxiliary switch, it is decreased by diverting it to
the output side with coupling inductance. The proposed
PFC converter controls output current and voltage in
very wide line and load range. This PFC converter has
simple structure, low cost and ease of control as well. In
this study, a detailed steady state analysis of the new
converter is presented, and the theoretical analysis is
verified exactly by 100 kHz and 300 W prototype. This
prototype has 98% total efficiency and 0.99 power factor
with sinusoidal current shape.
Here are the key steps to design a Hartley oscillator:
1. Choose the operating frequency fo. This will help determine component values.
2. Select the transistor. Consider gain, frequency response, power handling etc.
3. Calculate the inductance L required using the formula:
L = 1 / [4π2fo2C]
Where C is the total capacitance in the tank circuit.
4. Choose standard inductance value slightly higher than L.
5. Calculate the capacitance C required for resonance at fo using:
1 / [2π(LC)1/2] = fo
6. Choose standard capacitance values to obtain C.
7. Calculate
The document discusses operational amplifiers and their applications. It begins by defining an operational amplifier as a circuit that can perform mathematical operations like addition, subtraction, integration and differentiation. It then discusses the key components of an op-amp, including the differential amplifier input stage. Next, it defines a differential amplifier and describes its basic circuit. The rest of the document provides details on various op-amp applications, including integrators, differentiators, comparators, and multivibrators. It explains the circuitry and operation of each type of application.
The slides explain how a voltage inverter can be made using 555 timer in astable mode.
It contains a clear description of the working of the 555 timer and hence the voltage inverter.
- LEDs emit light when forward biased due to electron-hole recombination in materials like gallium arsenide. The color emitted depends on the material used, with variations in elements like gallium, phosphorus, and arsenic producing different colors.
- Tunnel diodes exhibit negative resistance between peak and valley voltages due to quantum mechanical tunneling effects. This property can be used for oscillation in tunnel diode oscillators.
- Varactor diodes act as variable capacitors, with capacitance varying inversely with applied reverse voltage, allowing them to be used for voltage-controlled oscillation.
The document discusses tunnel diodes and their operation. It explains that tunnel diodes use quantum tunneling effects to allow electrons to pass through a potential barrier. The document then provides energy band diagrams and descriptions of tunnel diode operation under forward and reverse bias. It discusses their applications as oscillators, switches, logic devices and amplifiers. The document also compares tunnel diodes to conventional PN diodes and describes other specialized electronic devices like varactor diodes and photodiodes.
An operational amplifier (op-amp) is an integrated circuit that can amplify or compare signals. It consists of transistors, resistors, and capacitors. Op-amps are used to build amplifiers, summers, integrators, differentiators, and comparators. They obey golden rules to make the difference between their input pins zero. Op-amps are also used in analog to digital converters, which sample analog signals and convert them to digital signals for processing.
The transformer coupled class A power amplifier was introduced to minimize low output power and efficiency issues of conventional class A amplifiers. It uses a transformer in the collector load circuit for impedance matching between the transistor and load. The transformer allows impedance matching by transforming the high impedance primary to a low impedance secondary connected to the load. This improves gain and efficiency over a standard class A amplifier by preventing signal power loss in resistors and providing DC isolation between stages.
This document discusses transistor biasing and faithful signal amplification in transistors. It begins by explaining that the basic function of a transistor is amplification, and that for faithful amplification the input circuit must remain forward biased and the output circuit must remain reverse biased during the signal. This is achieved through transistor biasing, which provides the proper zero-signal collector current, base-emitter voltage, and collector-emitter voltage. Several common biasing circuits are described, including base resistor, collector feedback resistor, and voltage divider methods. The key requirements for faithful amplification and the effects of improper biasing are illustrated. Transistor characteristics like the input curve and output curve are also discussed.
1. An integrated circuit is a circuit constructed on a single semiconductor wafer or chip that contains transistors, resistors, and capacitors interconnected to perform a given function.
2. Integrated circuits are classified as either digital or linear. Digital ICs operate using discrete voltage levels while linear ICs have a continuously variable output.
3. Some key characteristics of operational amplifiers include very high open loop gain, very high input impedance, very low output impedance, and the ability to invert or non-invert the input signal depending on the feedback configuration. Operational amplifiers are examples of linear integrated circuits.
The document describes an experiment on electronic circuits and simulation lab involving voltage shunt feedback amplifiers. It includes the aim, components, circuit diagrams, theory, design process, procedure, tabular column and expected results for analyzing the amplifier's characteristics both with and without feedback, including mid band gain, bandwidth, input and output impedance. Key aspects like frequency response will be measured and compared between the feedback and non-feedback configurations.
The document discusses the internal components and operation of the 741 operational amplifier integrated circuit. It describes the bias circuitry that generates reference currents for the entire circuit. It then explains the input, output, and compensation stages. The input stage contains transistors that create complementary current signals. The output stage and protection circuitry limit current to prevent overheating. The 741 is compensated internally using a resistor-capacitor network to maintain stability at high frequencies and gains. The document also covers topics like frequency response, slew rate, and the gain-bandwidth relationship of the 741 op-amp.
This document describes a circuit to automatically open and close a glass window using light sensors. The circuit includes a power supply unit with a step-down transformer, rectifier, and voltage regulators to provide stable DC power from 230V AC. A PIC microcontroller measures light levels with an analog-to-digital converter connected to light dependent resistors. When light levels cross a threshold, the PIC activates a relay to control a DC motor that opens or closes the window. The circuit provides a simple automatic window control system based on ambient light levels.
Design and fabrication of over voltage relay Prem Kumar
This document describes the design and fabrication of an over voltage relay to be integrated into a power system lab. It presents the circuit design which uses a transformer, rectifier, regulators, op-amp, resistors, capacitors, diode, potentiometer, and relay. The over voltage relay works by comparing the input voltage to a reference voltage using an op-amp circuit. If the input voltage is higher than the reference voltage, the relay will trip to protect equipment from overvoltage.
The document discusses operational amplifiers (op-amps) and their use in integrator and differentiator circuits. It defines an op-amp as an integrated circuit that amplifies input signals through high gain. An integrator circuit uses an op-amp with a capacitor in feedback, resulting in an output voltage that is inversely proportional to time. A differentiator circuit contains a capacitor in the signal path, producing an output equal to the derivative of the input voltage. Practical implementations of these circuits are also described, along with their applications in areas like analog computing and signal processing.
The document describes a multiple output power supply design for a DVD player with the following key points:
1. It provides 7.5W of continuous output power and 13W of peak power with outputs of 3.3V, 5V, 12V, and -12V regulated using a TinySwitch-PK controller in a flyback topology.
2. It achieves good cross-regulation between the 5V and 3.3V outputs through minimizing leakage and sum regulating the feedback.
3. It includes features for EMI filtering, surge protection, clamping, and a unique peak mode for boosting current limit during peaks loads.
This document describes an anti-bag snatching alarm circuit designed to prevent theft. The circuit uses an operational amplifier configured as a comparator to detect when a mono plug is detached from the circuit, activating a timer and alarm tone generator. A transistor amplifies the alarm tone to a loudspeaker. It operates on a 9V battery and produces a loud siren noise to draw attention if anyone attempts to snatch the bag containing the circuit. The document provides details on the components, working principle, applications and advantages of using this simple, low-cost anti-theft alarm system.
Oscillators convert DC to AC signals using a feedback loop that sustains oscillations. Common oscillator circuits include LC, RC, quartz, and relaxation oscillators. The Hartley oscillator uses a tapped coil and capacitor in a feedback loop to generate radio frequencies. The Colpitts oscillator also uses an LC tank circuit but with capacitors in the feedback path. The Franklin oscillator uses two transistors and an LC circuit, with each transistor inverting the phase to sustain oscillations. The Wein bridge oscillator is an RC circuit that produces sine waves with high quality resonance and tuning capabilities. Oscillators are used to generate signals for applications like radio transmission, testing equipment, and sensors.
This document provides an overview of the 555 and 556 timer integrated circuits (ICs). It describes their pinouts, operating voltages, output capabilities, and common circuit configurations including astable (oscillator), monostable (one-shot), and bistable modes. Example circuits and applications are given for each mode to generate square waves, timed pulses, and simple memory functions. Guidelines for selecting component values to achieve desired timing are also provided.
This document summarizes power semiconductor switches, including diodes, thyristors, bipolar junction transistors (BJTs), metal-oxide-semiconductor field-effect transistors (MOSFETs), insulated-gate bipolar transistors (IGBTs), gate turn-off thyristors (GTOs), and other developing switching devices. It describes the characteristics, features, and operating principles of these different types of switches through diagrams, images, and brief explanations.
The document describes the steps to create a 15V DC power supply. It includes circuit designing, simulation, component purchasing, breadboard testing, and PCB design using Altium. Key steps are transforming AC to DC using a rectifier and filter, regulating the voltage to 15V using LM7815 and LM7915 regulators, and verifying the circuit works by lighting LEDs and measuring output on a CRO. The PCB is created by printing the design on a copper board, etching away extra copper, drilling holes, soldering components, and testing the finished board.
Variable Power Supply with Digital Control with seven segments display is one of the applications of electronics to increase the facilities of life. It is facilitates the operation of voltage regulators around the electronics lab. It provides a system that is simple to understand and also to operate, a system that would be cheaper and affordable.
A New Active Snubber Circuit for PFC ConverterIDES Editor
In this paper, a new active snubber circuit is
developed for PFC converter. This active snubber circuit
provides zero voltage transition (ZVT) turn on and zero
current transition (ZCT) turn off for the main switch
without any extra current or voltage stresses. Auxiliary
switch turns on and off with zero current switching (ZCS)
without voltage stress. Although there is a current stress
on the auxiliary switch, it is decreased by diverting it to
the output side with coupling inductance. The proposed
PFC converter controls output current and voltage in
very wide line and load range. This PFC converter has
simple structure, low cost and ease of control as well. In
this study, a detailed steady state analysis of the new
converter is presented, and the theoretical analysis is
verified exactly by 100 kHz and 300 W prototype. This
prototype has 98% total efficiency and 0.99 power factor
with sinusoidal current shape.
Here are the key steps to design a Hartley oscillator:
1. Choose the operating frequency fo. This will help determine component values.
2. Select the transistor. Consider gain, frequency response, power handling etc.
3. Calculate the inductance L required using the formula:
L = 1 / [4π2fo2C]
Where C is the total capacitance in the tank circuit.
4. Choose standard inductance value slightly higher than L.
5. Calculate the capacitance C required for resonance at fo using:
1 / [2π(LC)1/2] = fo
6. Choose standard capacitance values to obtain C.
7. Calculate
The document discusses operational amplifiers and their applications. It begins by defining an operational amplifier as a circuit that can perform mathematical operations like addition, subtraction, integration and differentiation. It then discusses the key components of an op-amp, including the differential amplifier input stage. Next, it defines a differential amplifier and describes its basic circuit. The rest of the document provides details on various op-amp applications, including integrators, differentiators, comparators, and multivibrators. It explains the circuitry and operation of each type of application.
The slides explain how a voltage inverter can be made using 555 timer in astable mode.
It contains a clear description of the working of the 555 timer and hence the voltage inverter.
- LEDs emit light when forward biased due to electron-hole recombination in materials like gallium arsenide. The color emitted depends on the material used, with variations in elements like gallium, phosphorus, and arsenic producing different colors.
- Tunnel diodes exhibit negative resistance between peak and valley voltages due to quantum mechanical tunneling effects. This property can be used for oscillation in tunnel diode oscillators.
- Varactor diodes act as variable capacitors, with capacitance varying inversely with applied reverse voltage, allowing them to be used for voltage-controlled oscillation.
The document discusses tunnel diodes and their operation. It explains that tunnel diodes use quantum tunneling effects to allow electrons to pass through a potential barrier. The document then provides energy band diagrams and descriptions of tunnel diode operation under forward and reverse bias. It discusses their applications as oscillators, switches, logic devices and amplifiers. The document also compares tunnel diodes to conventional PN diodes and describes other specialized electronic devices like varactor diodes and photodiodes.
An operational amplifier (op-amp) is an integrated circuit that can amplify or compare signals. It consists of transistors, resistors, and capacitors. Op-amps are used to build amplifiers, summers, integrators, differentiators, and comparators. They obey golden rules to make the difference between their input pins zero. Op-amps are also used in analog to digital converters, which sample analog signals and convert them to digital signals for processing.
The transformer coupled class A power amplifier was introduced to minimize low output power and efficiency issues of conventional class A amplifiers. It uses a transformer in the collector load circuit for impedance matching between the transistor and load. The transformer allows impedance matching by transforming the high impedance primary to a low impedance secondary connected to the load. This improves gain and efficiency over a standard class A amplifier by preventing signal power loss in resistors and providing DC isolation between stages.
This document discusses transistor biasing and faithful signal amplification in transistors. It begins by explaining that the basic function of a transistor is amplification, and that for faithful amplification the input circuit must remain forward biased and the output circuit must remain reverse biased during the signal. This is achieved through transistor biasing, which provides the proper zero-signal collector current, base-emitter voltage, and collector-emitter voltage. Several common biasing circuits are described, including base resistor, collector feedback resistor, and voltage divider methods. The key requirements for faithful amplification and the effects of improper biasing are illustrated. Transistor characteristics like the input curve and output curve are also discussed.
1. An integrated circuit is a circuit constructed on a single semiconductor wafer or chip that contains transistors, resistors, and capacitors interconnected to perform a given function.
2. Integrated circuits are classified as either digital or linear. Digital ICs operate using discrete voltage levels while linear ICs have a continuously variable output.
3. Some key characteristics of operational amplifiers include very high open loop gain, very high input impedance, very low output impedance, and the ability to invert or non-invert the input signal depending on the feedback configuration. Operational amplifiers are examples of linear integrated circuits.
The document describes an experiment on electronic circuits and simulation lab involving voltage shunt feedback amplifiers. It includes the aim, components, circuit diagrams, theory, design process, procedure, tabular column and expected results for analyzing the amplifier's characteristics both with and without feedback, including mid band gain, bandwidth, input and output impedance. Key aspects like frequency response will be measured and compared between the feedback and non-feedback configurations.
The document discusses the internal components and operation of the 741 operational amplifier integrated circuit. It describes the bias circuitry that generates reference currents for the entire circuit. It then explains the input, output, and compensation stages. The input stage contains transistors that create complementary current signals. The output stage and protection circuitry limit current to prevent overheating. The 741 is compensated internally using a resistor-capacitor network to maintain stability at high frequencies and gains. The document also covers topics like frequency response, slew rate, and the gain-bandwidth relationship of the 741 op-amp.
This document describes a circuit to automatically open and close a glass window using light sensors. The circuit includes a power supply unit with a step-down transformer, rectifier, and voltage regulators to provide stable DC power from 230V AC. A PIC microcontroller measures light levels with an analog-to-digital converter connected to light dependent resistors. When light levels cross a threshold, the PIC activates a relay to control a DC motor that opens or closes the window. The circuit provides a simple automatic window control system based on ambient light levels.
Design and fabrication of over voltage relay Prem Kumar
This document describes the design and fabrication of an over voltage relay to be integrated into a power system lab. It presents the circuit design which uses a transformer, rectifier, regulators, op-amp, resistors, capacitors, diode, potentiometer, and relay. The over voltage relay works by comparing the input voltage to a reference voltage using an op-amp circuit. If the input voltage is higher than the reference voltage, the relay will trip to protect equipment from overvoltage.
The main feature of this power supply is, when no load is there it automatically switches off. It is a circuit which mainly act as a protector circuit and achieved through an arrangement of transistors and relay. Embedded system
requires a regulated power supply. This power supply circuit gives a variable regulated supply and switches off in no load condition.
The document describes the design of a voltage regulated power supply circuit using an operational amplifier (op-amp) with built-in overload protection. The circuit converts AC input to DC and uses an op-amp, diodes, capacitors, resistors, transistors and a transformer to regulate the output voltage. It provides a stable, adjustable DC voltage of up to 1 amp as load current and incorporates overload protection that cuts off the supply if load current exceeds 1 amp to prevent damage.
08_electronics.basics and introduction12vikknaguem
This document provides an overview of basic electronics concepts including circuits, power supplies, transistors, and impedance. It discusses basic circuit analysis and relations involving voltage, current, resistance, capacitance, and inductance. Examples are given of voltage dividers, battery output impedance, full-wave rectification using a diode bridge, voltage regulation using zener diodes and voltage regulator ICs, transistor operation in amplification and switching modes, and an improved zener regulator circuit using a transistor buffer.
08_electronics.basics and introduction23vikknaguem
This document provides an overview of basic electronics concepts including circuits, power supplies, transistors, and impedance. It discusses basic circuit analysis and relations involving voltage, current, resistance, capacitance, and inductance. Examples are given of voltage dividers, battery output impedance, full-wave rectification circuits, smoothing circuits using capacitors, zener diode voltage regulation, and transistor operation in amplification and switching modes.
This over/under voltage cut-out will save your costly electrical and electronic appliances from the adverse effects of very high and very low mains voltages.
This document provides instructions for building and testing a differentiator circuit using an op amp. Key points:
- The circuit uses an LM356 op amp instead of the diagrammed uA741. Resistors and capacitors can be combined to achieve desired values.
- A series resistor and feedback capacitor are added to the ideal differentiator circuit to form high-pass and low-pass filters, stabilizing the circuit and reducing noise.
- As frequency increases, the capacitor acts less like an open circuit and more like a short circuit. This changes the circuit's behavior from a differentiator to an inverting amplifier to an integrator.
- Phase shift between input and output will vary from 90°
This circuit automatically changes the power supply phase to deliver correct voltage when only one phase has the proper voltage. It uses relays to disconnect the load from the low voltage phase and connect it to another phase with higher voltage. When the voltage of the initial phase drops below 200V, a comparator switches on a transistor that energizes a relay. This disconnects the load from that phase and connects it to a different phase through another relay, providing power from the phase with sufficient voltage. It allows equipment to operate even when only one phase in a building has the correct voltage level.
Electromechanical and solid state relays are used in industrial and commercial applications. Electromechanical relays consist of an electromagnet, armature, spring, and set of contacts. They operate by using a small electrical signal to energize an electromagnet, which pulls the armature and closes the contacts to allow current from another circuit to flow. Relays allow isolation between control and load circuits. They are useful for switching higher power loads than transistors and can switch both AC and DC. However, relays are larger than transistors and cannot switch as rapidly. Relay specifications include coil voltage and current and contact ratings. Relays are commonly used in machine control applications.
This circuit automatically stops charging AA batteries when they are fully charged. It uses a relay driver section with 3 PNP transistors to control a relay based on the voltage across a 10 ohm resistor. When the battery voltage reaches 1.3V per cell, the voltage drop decreases and cuts off the transistors, de-energizing the relay to stop charging. It can charge partially discharged batteries to 7.35V total for 4 cells at 70mA, stopping when the voltage indicates the cells are fully charged.
- The OpEL will close at 4:30PM on Thursday Nov 8. Week 9 assignments are due Wednesday Nov 7 as usual.
- The make-up lab (photoflash) is due Wednesday Nov 14.
- The document provides information about operating a 555 timer chip in astable mode to generate pulses for a metronome circuit. It describes the internal components and operation of the 555 timer and how varying resistor values changes the output pulse frequency and duty cycle.
Many of the people have a phobia of darkness, so to assist them in such situation, we have explained a simple circuit. It will automatically turn on street light in the way of LEDs or bulb coupled with relay. Working this circuit is very much easy and also the power consumed by the circuit is very low because of the very few components used in the circuit.
The 555 timer IC is a versatile integrated circuit used in timer, pulse generation, and oscillator applications. It contains transistors, resistors, and diodes on a silicon chip. The 555 can be used in monostable, bistable, and astable modes to generate pulses or oscillations. It is commonly used in applications like blinking LEDs, timers, oscillators, and more due to its low cost, ease of use, and stability.
This document describes the design and construction of a variable regulated power supply circuit. The circuit uses a transformer, rectifier, filter capacitor and adjustable linear regulator to convert household AC power into a continuously adjustable DC output between 1.2 and 30 volts. Key components include a transformer, bridge rectifier, filtering capacitors, LM317 adjustable regulator, potentiometers for output voltage adjustment and trimming, and other passive components. The document provides the circuit diagram, lists components, and explains the working principle of how AC power is converted to a regulated DC output through rectification, filtering and linear voltage regulation.
Automatic street light using ldr and relayShivam Raidas
The document describes an automatic street light controller circuit that uses relays and an LDR (light dependent resistor). The circuit uses an LDR, which has a resistance that changes based on light levels, along with some other components connected to an operational amplifier IC. The circuit is able to automatically turn on street lights or household lights when it gets dark based on the changing resistance of the LDR. It provides light when needed using very few, low power components, requiring no manual operation or maintenance.
The document describes an automatic street light circuit that uses a light dependent resistor (LDR) to sense light levels and control a relay that switches a light on and off. When it is dark, the resistance of the LDR increases, which causes a transistor to turn on and energize the relay, powering the light. During the day when it is light outside, the LDR's resistance decreases and the transistor turns off, cutting power to the light. Key components of the circuit include an LDR, transistors, a relay, resistors, and a battery power supply. The circuit can be used to automatically switch any light on at night and off during the day based on light level changes.
Direct Coupled Transistor Logic (DCTL) is a type of logic circuit that is similar to Resistor-Transistor Logic (RTL) but connects the transistor bases directly to the collector outputs without base resistors. DCTL gates have fewer components, are more economical, and simpler to fabricate than RTL gates. DCTL can implement basic logic gates like NOR and NAND. It has advantages of low power dissipation and ability to operate using a single low voltage supply but has limitations related to increased base current and lower output voltage levels. DCTL finds real-life uses in applications requiring high speed and low power like large computers and digital watches.
This document provides an overview of basic electronics components and circuits. It begins with an introduction to passive components like resistors, capacitors, inductors, and transformers. It then covers analog circuits using transistors and operational amplifiers. The document provides details on circuit analysis and different types of filters. It explains concepts like resistors, capacitors, inductors, diodes, transistors, and operational amplifiers. Examples of common circuits are also presented like voltage dividers, rectifiers, and amplifiers.
This project report describes a security alarm circuit that uses a light dependent resistor (LDR) to detect intruders. When light falling on the LDR is interrupted, a monostable multivibrator circuit uses an IC 555 timer chip to activate a relay switch for 5-55 seconds, triggering an alarm. The circuit aims to provide inexpensive home protection and could also be used for novel applications at festivals.
1. Electus Distribution Reference Data Sheet: RELAYDRV.PDF (1)
RELAY DRIVING BASICS
Relays are components which allow a low-power circuit to
switch a relatively high current on and off, or to control signals +12V +12V
that must be electrically isolated from the controlling circuit RLY1 Q2
Vin R2
itself. Newcomers to electronics sometimes want to use a
D1
relay for this type of application, but are unsure about the
details of doing so. Here’s a quick rundown.
To make a relay operate, you have to pass a suitable ‘pull-in’ RLY2
and ‘holding’ current (DC) through its energising coil. And
generally relay coils are designed to operate from a particular D2
Vin R1
supply voltage — often 12V or 5V, in the case of many of the Q1
small relays used for electronics work. In each case the coil has
a resistance which will draw the right pull-in and holding
currents when it’s connected to that supply voltage. So the
basic idea is to choose a relay with a coil designed to operate A. NPN driver, relay on for Vin = +12V B. PNP driver, relay on for Vin = 0V
from the supply voltage you’re using for your control circuit & off for Vin = 0V & off for Vin = +12V
(and with contacts capable of switching the currents you want
to control), and then provide a suitable ‘relay driver’ circuit so
that your low-power circuitry can control the current through If our relay has a coil resistance of say 180Ω, so that it draws
the relay’s coil. Typically this will be somewhere between 25mA say 67mA at 12V, we’d need to reduce R1 to say 8.2kΩ, to
and 70mA. increase the base current to about 1.4mA. Conversely if the
Often your relay driver can be very simple, using little more relay coil is 360Ω and draws only 33mA, we could increase R1
than an NPN or PNP transistor to control the coil current. All to 15kΩ, giving about 0.76mA of base current. Each time we
your low-power circuitry has to do is provide enough base go for about twice the relay coil current divided by Q1’s hFE —
current to turn the transistor on and off, as you can see from get the idea?
diagrams A and B. As you can see a power diode D1 (1N4001 or similar) is
In A, NPN transistor Q1 (say a BC337 or BC338) is being connected across the relay coil, to protect the transistor from
used to control a relay (RLY1) with a 12V coil, operating from damage due to the back-EMF pulse generated in the relay coil’s
a +12V supply. Series base resistor R1 is used to set the base inductance when Q1 turns off.
current for Q1, so that the transistor is driven into saturation The basic NPN circuit in diagram A is fine if you want the
(fully turned on) when the relay is to be energised. That way, relay to energise when your control voltage Vin is high (+12V),
the transistor will have minimal voltage drop, and hence and be off when Vin is low (0V). But what if you want the
dissipate very little power — as well as delivering most of the opposite? That’s where you’d opt for a circuit like that shown
12V to the relay coil. in diagram B, using a PNP transistor like the BC327 or BC328.
How do you work out the value of R1? It’s not hard. Let’s This is essentially the same circuit as in A, just swung around
say RLY1 needs 50mA of coil current to pull in and hold to suit the PNP transistor’s polarity.
reliably, and has a resistance of 240Ω so it draws this current This time transistor Q2 will turn on and energise the relay
from 12V. Our BC337/338 transistor will need enough base when Vin is low (0V), and will turn off when Vin is high (+12V).
current to make sure it remains saturated at this collector Otherwise everything works just as before, and the value of
current level. base resistor R2 is worked out in the same way as for R1. In
To work this out, we simply make sure that the base current fact because the minimum hFE of the BC327/328 PNP
is greater than this collector current divided by the transistor’s transistors is also 100 at 100mA, you could use exactly the
minimum DC current gain hFE. So as the BC337/338 has a same values of R2 to suit each relay resistance/current.
minimum hFE of 100 (at 100mA), we’d need to provide it with The simple transistor driver circuits of A and B are very low
at least 50mA/100 = 0.5mA of base current. in cost, and are generally fine for driving most relays. However
In practice, you’d give it roughly double this value, say 1mA there may be occasions, such as when your control circuit is
of base current, just to make sure it does saturate. So if your based on CMOS logic, where the base current needed by
control signal Vin was switching between 0V and +12V, you’d these circuits is a bit too high.
give R1 a value of say 11kΩ, to provide the 1mA of base For these situations the circuit shown in C might be of
current needed to turn on both Q1 and the relay. interest, because it needs rather less input current. As you can
see it uses a readily available and very low cost 555 IC as the
relay driver, plus only one extra component: bypass capacitor
+5V C1.
RLY3 Although we normally think of the 555 as a timer/oscillator,
D3 it’s actually very well suited for driving a small relay. Output pin
4 8 3 can both source and sink 200mA (enough to handle most
7
small relays comfortably), and the internal flipflop which
6 IC1 3 controls its output stage is triggered swiftly between its two
Vin R3 states by internal comparators connected to the two sensing
555
2 inputs on pins 2 and 6. When these pins are taken to a voltage
above 2/3 the supply voltage, the output switches low (0V);
1 5 then they are taken below 1/3 the supply voltage, the output
C1 swings high. And the 555 can happily work at 5V, as you can
0.1uF see, so it’s very suitable for driving a 5V relay coil from this
supply voltage.
C. 555 'timer' IC as relay driver. Relay on for Vin > 2/3Vcc (3.3V),
Because the sensing inputs of the 555 are voltage sensing
& off for Vin < 1/3Vcc (1.66V) and need only a microamp or so of current, the value of input