Controllability and Observability.

Controllability and observability are two very important things related to state space analysis. There are many tests for checking controllability and obervability and these tests are very essential during the design of a control system using state space approach.

Controllability verifies whether is state variable is useful or not. It checks whether a state variable can be manipulated for obtaining the required output. If a state variable is not controllable then there is no meaning in selecting it for any operation. If a particular state variable is found uncontrollable , then it is left untouched and any other state variable which is controllable is selected for operations.

A system is said to be completely state controllable if it is possible to change the system from any initial stage X(t0) to any required stage X(td) using a control vector U(t). Kalman’s test and Gilberts test are the two common methods used for testing controllability.

Gilbert’s method for checking controllability is done under two cases.

1)When the eigen values of the system matrix are distinct.

In this case the system matrix can be diagonalized and can be converted to the canonical form by giving a transformation X=MZ. M is the modal matrix derived from the system matrix and Z is the transformed state variable matrix.

Consider a system with state model represented by the equations

X = AX + BU

Y = CX + DU

The model is transformed into the canonical form as follows,

Z = ?Z + B˜U

Y = C˜Z + DU

Where ?= MA¯¹M,   B˜ = M¯¹B and C˜ = CM

The system is completely state controllable if the matrix B doesnot have any row with all zeros.

2) Eigen values of the system matrix are repeated.

In this situation it is impossible to diagonalize the system matrix and it can be converted to Jordan canonical form.

Consider a system with state model represented by the equations

X = AX + BU

Y = CX + DU

The model is transformed into the Jordan canonical form as follows,

Z = JZ + ?˜U

Y = C˜Z + DU

Where J = M A¯¹M,   B˜ = M¯¹B and C˜ = CM

The system will be completely state controllable if elements of any row of B that correspond to the last row of each Jordan block are not all zero and the rows corresponding to other state variables must not have all zeros.

View the original article here

One transistor code lock

Description.

This is of course the simplest electronic code lock circuit one can make. The circuit uses one transistor, a relay and few passive components. The simplicity does not have any influence on the performance and this circuit works really fine.

The circuit is nothing but a simple transistor switch with a relay at its collector as load. Five switches (S0 to S4) arranged in series with the current limiting resistor R2 is connected across the base of the transistor and positive supply rail. Another five switches (S5 to S9) arranged in parallel is connected across the base of the transistor and ground. The transistor Q1 will be ON and relay will be activated only if all the switches S0 to S4 are ON and S5 to S9 are OFF. Arrange these switches in a shuffled manner on the panel and that it. The relay will be ON only if the switches S0 to S9 are either OFF or ON in the correct combination. The device to be controlled using the lock circuit can be connected through the relay terminals. Transformer T1, bridge D1, capacitor C1 forms the power supply section of the circuit. Diode D2 is a freewheeling diode. Resistor R1 ensures that the transistor Q1 is OFF when there is no connection between its base and positive supply rail.

Circuit diagram.

Notes.

• This circuit can be assembled on a Vero board.
• Switch S1 is the lock’s power switch.
• The no of switches can be increased to make it hard to guess the combination.
• Transistor 2N2222 is not very critical here. Any low or medium power NPN transistor will do the job.

555 Timer – A Complete Basic Guide

A complete basic tutorial of 555 Timer IC.

This article covers every basic aspect of 555 Timer IC. You may already know that SE/NE 555 is a Timer IC introduced by Signetics corporation in 1970′s. In this article we cover the following information about 555 Timer IC.

1. Introduction to 555 Timer IC

2. 555 Timer IC Pin Configuration

3. Basics of 555 Timer

4. Block Diagram

5. Working Principle

6. Download Data Sheet

1. Introduction

555 timer IC

One of the most versatile linear ICs is the 555 timer which was first introduced in early 1970 by Signetic Corporation giving the name as SE/NE 555 timer. This IC is a  monolithic timing circuit that can produce accurate and highly stable time delays or oscillation. Like other commonly used op-amps, this IC is also very much reliable, easy to use and cheaper in cost. It has a variety of applications including monostable and astable multivibrators, dc-dc converters, digital logic probes, waveform generators, analog frequency meters and tachometers, temperature measurement and control devices, voltage regulators etc. The timer basically operates in one of the two modes either as a monostable (one-shot) multivibrator or as an astable (free-running) multivibrator.The SE 555 is designed for the operating temperature range from – 55°C to 125° while the NE 555 operates over a temperature range of 0° to 70°C.

The important features of the 555 timer are :

• It operates from a wide range of power supplies ranging from + 5 Volts to + 18 Volts supply voltage.
• Sinking or sourcing 200 mA of load current.
• The external components should be selected properly so that the timing intervals can be made into several minutes Proper selection of only a few external components allows timing intervals of several minutes along with the frequencies exceeding several hundred kilo hertz.
• It has a high current output; the output can drive TTL.
• It has a temperature stability of 50 parts per million (ppm) per degree Celsius change in temperature, or equivalently 0.005 %/ °C.
• The duty cycle of the timer is adjustable with the maximum power dissipation per package is 600 mW and its trigger and reset inputs are logic compatible.

2. IC Pin Configuration

555 Timer IC Pin Configuration

The 555 Timer IC is available as an 8-pin metal can, an 8-pin mini DIP (dual-in-package) or a 14-pin DIP.

This IC consists of 23 transistors, 2 diodes and 16 resistors. The explanation of terminals coming out of the 555 timer IC is as follows. The pin number used in the following discussion refers to the 8-pin DIP and 8-pin metal can packages.

Pin 1: Grounded Terminal: All the voltages are meas­ured with respect to this terminal.

Pin 2: Trigger Terminal: This pin is an inverting input to a comparator that is responsible for transition of flip-flop from set to reset. The output of the timer depends on the amplitude of the external trigger pulse applied to this pin.

Pin 3: Output Terminal: Output of the timer is avail­able at this pin. There are two ways in which a load can be connected to the output terminal either between pin 3 and ground pin (pin 1) or between pin 3 and supply pin (pin 8). The load connected between pin 3 and ground supply pin is called the normally on load and that connected between pin 3 and ground pin is called the normally off load.

Pin 4: Reset Terminal: To disable or reset the timer a negative pulse is applied to this pin due to which it is referred to as reset terminal. When this pin is not to be used for reset purpose, it should be connected to + V_CC to avoid any possibility of false triggering.

Pin 5: Control Voltage Terminal: The function of this terminal is to control the threshold and trigger levels. Thus either the external voltage or a pot connected to this pin determines the pulse width of the output waveform. The external voltage applied to this pin can also be used to modulate the output waveform. When this pin is not used, it should be connected to ground through a 0.01 micro Farad to avoid any noise problem.

Pin 6: Threshold Terminal: This is the non-inverting input terminal of comparator 1, which compares the voltage applied to the terminal with a reference voltage of 2/3 V_CC. The amplitude of voltage applied to this terminal is responsible for the set state of flip-flop.

Pin 7 : Discharge Terminal: This pin is connected internally to the collector of transistor and mostly a capacitor is connected between this terminal and ground. It is called discharge terminal because when transistor saturates, capacitor discharges through the transistor. When the transistor is cut-off, the capacitor charges at a rate determined by the external resistor and capacitor.

Pin 8: Supply Terminal: A supply voltage of + 5 V to + 18 V is applied to this terminal with respect to ground (pin 1).

3. 555 Timer Basics

The 555 timer combines a relaxation oscillator, two comparators, an R-S flip-flop, and a discharge capacitor.

R-S Flip-Flop: – A pair of cross-coupled transistors is shown in figure. Each collector drives the opposite base through resistance R_B. In such circuit one transistor is saturated while the other is cut-off. For instance, if transistor Q₁ is saturated, its collector voltage is almost zero. So there is no base drive for transistor Q₂ and it goes into cut-off and its collector voltage approaches + V_CC. This high voltage produces enough base current to keep transistor Q₁ in saturation.

On the other hand if transistor Q₁ is cut-off, its collector voltage, which is approximately equal to + V_CC, drives the transistor Q₂ into saturation. The low collector voltage (which is approximately to zero) of this transistor then keeps the transistor Q₂ in cut-off.Depending on which transistor is saturated, the Q output is either low or high. By adding more components to the circuit, an R-S flip-flop is obtained. R-S flip-flop is a circuit that can set the Q output to high or reset it low. Incidentally, a complementary (opposite) output Q is available from the collector of the other transistor.

Figure shows the schematic symbol for an R-S flip-flop of any design. The circuit latches in either two states. A high S input sets Q to high; a high R input resets Q to low. Output Q remains in a given state until it is triggered into the opposite state.

Basic Timing Concept

Figure illustrates some basic ideas that will prove useful in coming blog posts of the 555 timer. Assuming output Q high, the transistor is saturated and the capacitor voltage is clamped at ground i.e. the capacitor C is shorted and cannot charge.

The non-inverting input voltage of the comparator is referred to as the threshold voltage while the inverting input voltage is referred to as the control voltage. With R-S flip flop set, the saturated transistor holds the threshold voltage at zero. The control voltage, however, is fixed at 2/3 V_CC (i.e. at 10 V) because of the voltage divider.

Suppose that a high voltage is applied to the R input. This resets the flip-flop R-Output Q goes low and the transistor is cut-off. Capacitor C is now free to charge. As this capacitor C charges, the threshold voltage rises. Eventually, the threshold voltage becomes slightly greater than (+ 10 V). The output of the comparator then goes high, forcing the R S flip-flop to set. The high Q output saturates the transistor, and this quickly discharges the capacitor. The two waveforms are depicted in figure. An exponential rise is across the capacitor C, and a positive going pulse appears at the output Q. Thus capacitor voltage V_C is exponential while the output is rectangular, as illustrated in figure.

4. Block Diagram

Block Diagram -555 Timer

The block diagram of a 555 timer is shown in the above figure. A 555 timer has two comparators, which are basically 2 op-amps), an R-S flip-flop, two transistors and a resistive network.

• Resistive network consists of three equal resistors and acts as a voltage divider.
• Comparator 1 compares threshold voltage with a reference voltage + 2/3 V_CC volts.
• Comparator 2 compares the trigger voltage with a reference voltage + 1/3 V_CC volts.

Output of both the comparators is supplied to the flip-flop. Flip-flop assumes its state according to the output of the two compa­rators. One of the two transistors is a discharge transis­tor of which collector is connected to pin 7. This tran­sistor saturates or cuts-off according to the output state of the flip-flop. The saturated transis­tor provides a discharge path to a capacitor con­nected externally. Base of another transistor is connected to a reset terminal. A pulse applied to this terminal resets the whole timer irrespective of any input.

5. Working Principle

Refer Block Diagram of 555 timer IC given above:

Comparator 1 has a threshold input (pin 6) and a control input (pin 5). In most applications, the control input is not used, so that the control voltage equals +2/3 V_CC. Output of this comparator is applied to set (S) input of the flip-flop. Whenever the threshold voltage exceeds the control voltage, comparator 1 will set the flip-flop and its output is high. A high output from the flip-flop saturates the discharge transistor and discharge the capacitor connected externally to pin 7. The complementary signal out of the flip-flop goes to pin 3, the output. The output available at pin 3 is low. These conditions will prevail until comparator 2 triggers the flip-flop. Even if the voltage at the threshold input falls below 2/3 V_CC, that is comparator 1 cannot cause the flip-flop to change again. It means that the comparator 1 can only force the flip-flop’s output high.

To change the output of flip-flop to low, the voltage at the trigger input must fall below + 1/3 Vcc. When this occurs, comparator 2 triggers the flip-flop, forcing its output low. The low output from the flip-flop turns the discharge transistor off and forces the power amplifier to output a high. These conditions will continue independent of the voltage on the trigger input. Comparator 2 can only cause the flip-flop to output low.

From the above discussion it is concluded that for the having low output from the timer 555, the voltage on the threshold input must exceed the control voltage or + 2/3 V_CC. They also turn the discharge transistor on. To force the output from the timer high, the voltage on the trigger input must drop below +1/3 V_CC. This also turns the discharge transistor off.

A voltage may be applied to the control input to change the levels at which the switching occurs. When not in use, a 0.01 nano Farad capacitor should be connected between pin 5 and ground to prevent noise coupled onto this pin from causing false triggering.

Connecting the reset (pin 4) to a logic low will place a high on the output of flip-flop. The discharge transistor will go on and the power amplifier will output a low. This condition will continue until reset is taken high. This allows synchronization or resetting of the circuit’s operation. When not in use, reset should be tied to +V_CC.

Download 555 Timer Data Sheet:

To know more about NE/SE 555 timer IC check out/download the datasheet. – NE-SE 555 Timer Datasheet

555 Timer Circuits and Projects

CircuitsToday is listing some simple 555 timer circuits that have already been published in our site before. To know about the basics of NE 555 along with the timer circuit schematic, click on the links below.

555 Timer Circuit Schematic and Working Principle

555 Timer Monostable Circuit

555 Timer Oscillator Circuit

555 as an Astable Multivibrator

LM 555 Datasheet

From the articles above you will also get the idea about its duty cycle and also other 555 timer applications. Here are the links of some easy 555 IC circuits with complete description and circuit diagram. A small description is given for each link to give you a small idea about the circuit.

1. 7-Segment Counter Circuit

This timer circuit is wired as an astable multivibrator to display a seven segment counter with the help of the counter IC CD 4033. This circuit is mostly added on to other circuits so as to make it more attractive by displaying a counter. The timer circuit is used to trigger the counter IC, which in turn advances each count on the seven segment LED display LT543. The complete details about the circuit and its circuit diagram are given in the original article.

2. Flasher Circuit using NE 555

A 555 LED Flasher circuit uses an astable multivibrator which produces pulses for flashing the lamp. Two resistors are set in the circuit to control the flashing rate. A half-wave rectifier, a transistor, and a TRIAC is used to drive the load. The circuit shown in the original post had some mistakes and the modified circuit is also shown right below the original post. Also take a look at the special notes as you are testing the circuit in live, and may cause potential shock hazards.

3. Photo Switch Circuit

This circuit uses a relay and a sensor to sense and switch when the light intensity crosses a certain limit. A Light Dependent Resistor is used as the sensor. The timer is connected to two transistors to drive the relay. Take a look at the complete working of the circuit in the original link given above. Also read the special notes given in the article to ensure that the procedures followed to make the circuit work are done correctly.

4. InfraRed (IR) Sensor/Detector

This circuit has applications as a proximity detector or liquid level detector. It operates by detecting the distance from the target by reflection of an infra-red beam. The timer output is designed for a duty cycle of 0.8 milliseconds, with a frequency of 120 Hertz and 300 milliampere peak current. Such a timer drives the infrared LED. An LM 358 IC is also used in the circuit as a comparator so that it receives the signal from one diode, as soon as it gets the infrared signal from another diode, and passes it on to the inverting input of the IC. The detailed idea of the circuit can be obtained from the main article.

5. Remote Controlled Switch Circuit

This circuit is used to switch on and off an electrical appliance using a TV remote. The signals are sensed using a sensor IC called TSOP 1738. The IC output will be high when it is not disturbed by any signal.  This makes the transistor in the OFF state. If a signal with a frequency of about 38 Kilohertz falls on the IC, its output becomes low. This causes the transistor to conduct and thus sends a negative pulse to the timer IC, designed to act as a monostable multivibrator. Take a look at the circuit diagram and the detailed working on the main article.

6. Sensitive Intruder Alarm Circuit

The circuit is used to produce an alarm as soon as an intruder passes nearby the circuit. It can be setup on your home premises for safety reasons. The circuit uses a LDR to sense the change in light due to the reflection of the intruder. This output is given to an op-amp comparator circuit.

7. Infrared Motion Detector Circuit

An astable multivibrator circuit is designed with the help of a timer IC and an infrared diode is used to produce infrared beams which are sensed by a phototransistor as soon as it is cut due to the motion of an intruder.

8. Rain Alarm Circuit

This circuit is used to produce an alarm as soon as rain starts to pour in. The main components of the circuit are two transistors and a timer IC. A sensor is used to sense the fall of rain water and its output is given to a switch and thus to two transistors.

9. Missing Pulse Detector Circuit Using NE555

This circuit is used to find a missing pulse or abnormally long period between two consecutive pulses in a train of pulses. Such circuits can be used to detect the intermittent firing of the spark plug of an automobile or to monitor the heart beat of a sick patient.

10. Mobile Incoming Call Indicator

This circuit can be used to escape from the disturbance caused due to mobile phone rings when you are at home. All you have to do is place the circuit near your mobile phone, and it will give you a visual indication even if the ringer is deactivated.

11. Musical Horn Circuit

Two 555 timer IC’s are combined to produce a musical horn. The output of the first IC is connected to the discharge pin of the second IC. Both of them are connected to work as astable multivibrators.

12. 10 Minute Timer Circuit

This circuit is used to make an alarm to wake you after ten minutes. Here, the circuit uses an LED instead of a buzzer. The circuit can be modified in your own way. The circuit consists of only a timer circuit designed as a monostable multivibrator.

13. Brightness Controller for Low Power Lamps

This circuit helps you to reduce and increase the brightness of low power incandescent lamps. The timer IC is designed as an astable multivibrator with variable duty cycle. A transistor is also used whose input will be driven by the timer circuit. The output of the transistor drives the lamp. The duty cycle of the multivibrator can be changed with the help of a potentiometer.

14. Flashing LED Unit

A 555 LED Flasher circuit is used to produce a rotating effect when the LEDs are arranged properly. The circuit has very low current consumption and can be operated from even 3V button cells. An astable multivibrator circuit is set with the help of the timer IC with a duty cycle of 50% and 4Hz frequency. Another timer IC is also used to work as a trigger pulse inverter.

15. Ding-Dong Sound Generator

The cicuit consists of two SE 555 timers that is toggled between two frequencies to produce a ding-dong sound. The first one is connected to the second in such a way that the frequency of the second NE555 IC is modulated by the output from the first IC.

View the original article here

555 Timer as Monostable Multivibrator

A monostable multivibrator (MMV) often called a one-shot multivibrator, is a pulse generator circuit in which the duration of the pulse is determined by the R-C network,connected externally to the 555 timer. In such a vibrator, one state of output is stable while the other is quasi-stable (unstable). For auto-triggering of output from quasi-stable state to stable state energy is stored by an externally connected capaci­tor C to a reference level. The time taken in storage determines the pulse width. The transition of output from stable state to quasi-stable state is accom­plished by external triggering. The schematic of a 555 timer in monostable mode of operation is shown in figure.

555-timer-monostable-multivibrator

Monostable Multivibrator Circuit details

Pin 1 is grounded. Trigger input is applied to pin 2. In quiescent condition of output this input is kept at + V_CC. To obtain transition of output from stable state to quasi-stable state, a negative-going pulse of narrow width (a width smaller than expected pulse width of output waveform)  and  amplitude of greater than + 2/3 V_CC is applied to pin 2. Output is taken from pin 3. Pin 4 is usually connected to + V_CC to avoid accidental reset. Pin 5 is grounded through a 0.01 u F capacitor to avoid noise problem. Pin 6 (threshold) is shorted to pin 7. A resistor R_A is connected between pins 6 and 8. At pins 7 a discharge capacitor is connected while pin 8 is connected to supply V_CC.

555 IC Monostable Multivibrator Operation.

555 monostable-multivibrator-operation

For explain­ing the operation of timer 555 as a monostable multivibrator, necessary in­ternal circuitry with external connections are shown in figure.

The operation of the circuit is ex­plained below:

Initially, when the output at pin 3 is low i.e. the circuit is in a stable state, the transistor is on and capacitor- C is shorted to ground. When a negative pulse is applied to pin 2, the trigger input falls below +1/3 V_CC, the output of comparator goes high which resets the flip-flop and consequently the transistor turns off and the output at pin 3 goes high. This is the transition of the output from stable to quasi-stable state, as shown in figure. As the discharge transistor is cut­off, the capacitor C begins charging toward +V_CC through resistance R_A with a time constant equal to R_AC. When the increasing capacitor voltage becomes slightly greater than +2/3 V_CC, the output of comparator 1 goes high, which sets the flip-flop. The transistor goes to saturation, thereby discharging the capacitor C and the output of the timer goes low, as illustrated in figure.

Thus the output returns back to stable state from quasi-stable state.

The output of the Monostable Multivibrator remains low until a trigger pulse is again applied. Then the cycle repeats. Trigger input, output voltage and capacitor voltage waveforms are shown in figure.

Monostable Multivibrator Design Using 555 timer IC

The capacitor C has to charge through resistance R_A. The larger the time constant R_AC, the longer it takes for the capacitor voltage to reach +2/3V_CC.

In other words, the RC time constant controls the width of the output pulse. The time during which the timer output remains high is given as

t_p = 1.0986 R_AC
where R_A is in ohms and C is in farads. The above relation is derived as below. Voltage across the capacitor at any instant during charging period is given as

v_c = V_CC (1- e^-t/R_AC)

Substituting v_c = 2/3 V_CC in above equation we get the time taken by the capacitor to charge from 0 to +2/3V_CC.

So +2/3V_CC. = V_CC. (1 – e^-t/RAC)   or   t – R_AC log_e 3 = 1.0986 R_AC

So pulse width, t_P = 1.0986 R_AC s 1.1 R_AC

The pulse width of the circuit may range from micro-seconds to many seconds. This circuit is widely used in industry for many different timing applications.

555 Timer Oscillator

A voltage-controlled oscillator (VCO) using the timer 555 is shown in figure.

555-timer-voltage-controlled-oscillator

The circuit is sometimes called a voltage-to-frequency converter because the output frequency can be changed by changing the input voltage.

As discussed in previous blog posts, pin 5 terminal is voltage control terminal and its function is  to control the threshold and trigger levels. Normally, the control voltage is ++2/3V_CC because of the internal voltage divider. However, an external voltage can be applied to this terminal directly or through a pot, as illustrated in figure, and by adjusting the pot, control voltage can be varied. Voltage across the timing capacitor is depicted in figure, which varies between +V_control and ½ V_control. If control voltage is increased, the capacitor takes a longer to charge and discharge; the frequency, therefore, decreases. Thus the fre­quency can be changed by changing the control volt­age. Incidentally, the control voltage may be made available through a pot, or it may be output of a transistor circuit, op-amp, or some other device.

Police siren using NE555

Description.

A lot of electronic circuits using NE555 timer IC are already published here and this is just another one.Here is the circuit diagram of a police siren based on NE55 timer IC. The circuit uses two NE555 timers ICs and each of them are wired as astable multivibrators.The circuit can be powered from anything between 6 to 15V DC and is fairly loud.By connecting an additional power amplifier at the output you can further increase the loudness.

IC1 is wired as a slow astable multivibrator operating at around 20Hz @ 50% duty cycle and IC2 is wired as fast astable multivibrator operating at around 600Hz.The output of first astable mutivibrator is connected to the control voltage input (pin5) of IC2. This makes the output of IC2 modulated by the output frequency of IC1, giving a siren effect. In simple words, the output frequency of IC2 is controlled by the output of IC1.

Circuit diagram.

Notes.

• The circuit can be assembled on a Perf board.
• I used 12V DC for powering the circuit.
• Instead of using two NE55 timer ICs, you can also use a single NE556 timer.
• NE556 is nothing but two NE555 ICs in one package.
• Refer the datasheets of NE555 and NE556 to have a clear idea.
• Speaker can be a 64ohm, 500mW one.

Electronic Seminar Topics

CircuitsToday is listing some of the latest electronic seminar topics that have already been published before. A small brief idea about the seminar topic is also given below, so that you can choose the right one to present. To know more about the topic click on the main heading. There are seminar topics for Electronics and Instrumentation and Electronics and Communication students. Besides, these seminar topics on electronics have been explained very neatly with diagrams so that you can gain a lot of information as well.

1.       Working of MAGLEV Trains

This seminar topic gives a detailed explanation about one of the world’s fastest transportation concept called MAGLEV Train, which works on the principle of Magnetic Levitation. The comparison between a MAGLEV train and a conventional train is also given along with diagrams. The speed of such trains and its commercial use in different countries are also explained. Two types of technologies that are used to drive the train called Electromagnetic Suspension (EMS) and Electro-dynamic Suspension are also explained in detail. The pros and cons of such a train and its environmental friendliness are also given in the post.

2.       How Global Positioning System (GPS) Works?

Almost all cars have GPS installed in them. This helps the driver to reach his destination without getting lost. They can also be installed in mobiles. This topic can is very suitable for communication engineering students. The working f GPS is explained with a video and a detailed description. A method called trilateration is also explained. This method is the basis on finding the exact position you are presently in. The different methods for calculating the distance and location of the satellite and receiver for knowing your position is also explained. The advantages, applications, and the benefits of using differential GPS system are also explained.

3.       Augmented Reality (AR) Technology

Augmented Reality deals with the integration of the real and virtual world so that graphics can be seen in a 3-D format. Thus, a widely produced graphics in such a technology will surely enhance everyone’s perception of the real world. The basic components used for this technology like displays, tracking and orientation methods, softwares used are all explained in detail. Its applications in various fields like gaming and entertainment, education, security and defence, and medicine is also explained in detail.

4.       Nanotechnology

This article describes the definition, history and concept of nanotechnology in detail. Nanotechnology mainly deals with the method by which full functional objects can b manufactured in a molecular scale. The article also shows a figure in which the usual scale of a common man made material is compared with nanomaterials. Two basic concepts of this technology called the bottom-up concept and the top-down concept are also explained in detail. After going through this technology, you could check out further informative posts by clicking on the link – More on Nanotechnology

5.       Working of Facial Recognition System

This topic mainly deals with the use of softwares combined with electronics to detect a person from a huge crowd. This is mainly used by law enforcement agencies, and also in ATM’s. The article mainly deals with the different methods used to recognize a person with almost 99% accuracy. A detailed figure showing the different nodal points that are used by the software to compare the original photo with the video captured one is shown in the article. The different comparison procedures like vector template, local feature analysis, and surface texture analysis is also explained in the post. The advantages, disadvantages, and applications are also given.

6.       Working of Electronic Ink (E-ink) Technology

The method of using a type of digital ink to write on screens is used in this technology. Three components are used for manufacturing this ink. They include millions of microcapsules, the ink substance present in an oily form which fills the microcapsules, and the negative charged pigmented chips or balls which float inside the microcapsules. This article describes in detail about the exact working of this material, and about the type of screen that is used for this purpose. A figure showing the working and the uses of this technology can also be seen in the link above.

7.       Working of Fingerprint Scanner

A finger printer scanner is used by most companies to restrict outsiders from coming in. Even laptops have fingerprint scanners to allow the owner to restrict others from using his confidential data, or websites, and so on. This article gives a detailed study of the use of such devices, the way it works, how fingerprint is analyzed, and so on. The two types of fingerprint scanner – optical scanner and capacitance scanner are also explained. The working is explained with a well described block diagram, along with the devices’ advantages and disadvantages.

8.       Photonic Integrated Circuit (PIC)

Photonic Integrated Circuit (also known as PIC), is a complex integrated circuit which incorporates a lot of optical devices to form a single photonic circuit. The article describes the difference between a PIC and the conventional Electronic Integrated Circuits. A figure of a GaAs-InP Photonic integrated circuit is also explained in detail. Two basic photonic integration methods like Hybrid Photonic Integration and Monolithic Photonic Integration are also explained in this article. You can also look at the advantages and applications of PIC from the link above.

9.       Working of 3-D TV

Nowadays, most movies are made in 3-D and the special effects that are brought into the movies make it cooler. 3-D Technology is explained in detail, including the type of glasses that are used to watch such movies, and how to make them by yourself. The basics of 3-D are explained along with its difference with 2-D. Stereoscopic TV and Autostereoscopic TV is also explained in this post. The future development that is going to happen to this technology is also given in this article.

10.   RedTacton Technology

RedTacton Technology is a concept that refers to the transmission of signals at very high speeds through the human body. Just like the Bluetooth Technology, this concept is also known to be wireless in nature. The transmitter and receiver used in RedTacton and is explained with the help of a figure. Some interesting features of the technology like touch, media, and broadband are also explained with an image. Its applications and comparison with other wireless technologies like w-fi, RFID, Bluetooth, and W-CDMA are also explained.

11.   Smart Antennas

Smart Antennas are adaptive array antennas that are designed for one main purpose – to maintain the high efficiency in digital wireless communication systems. The objective is obtained by taking the advantage of the diversity effect at the transceiver of the wireless system that is the source and the destination. This concept has already been adapted in some wireless communication systems as special antenna arrays are used with signal processing algorithms which can easily locate and track the different wireless targets such as mobiles. The two functions of smart antennas namely estimation of direction of arrival, and beamforming method is also explained in detail. Adaptive array antennas and phased array antennas are also explained in the article. The difference between this antenna and the conventional one is also given along with its advantages and disadvantages.

12.   Working of Standing Wave Ratio (SWR) Meters

This device is used to measure the standing wave ratio in a communication line. The meter will denote the exact mismatch between the transmission line and the load, thus helping to know the degree of effectiveness of the impedance matching efforts. The article explains in detail about the topic with a neat figure. The SWR bridge circuit and the problems with that could occur with he use of SWR meter is also explained in the article.

13.   3-D Handwriting Technology – Make Functional Electronic Circuits on Paper Using Silver Ink Pen

The basic method for making electronic circuits is by designing a PCB or a Vera board for the purpose. This technology called 3-D handwriting simplifies the whole process by just drawing the layout on a paper with a silver coloured liquid metal ink. An image showing an illustration of the technology is given in the original post. The pen used for drawing the circuit is made of an ink with conductive property.

14.   Faster Data Transfer with Point and Paste Technology

All types of communication between business people and also friends are now made through e-mails and social networking sites. But, a greater method to send data would be through the so called “Point and Paste Technology”. The method uses a temporary storage for the data while you point out at a certain data on your device and just touch another device where it is to be stored.

15.   Lenticular Lenses

This i s a completely new technology through which you get to see 3D movies with the same effect, and that too without the use of glasses. The basic idea used behind this technology is called lenticular viewing. Tiny cylindrical plastic lenses are placed on the screen of an LCD tv. This sheet gives all the 3-D effects needed. The detailed explanation is given in the post above with neat figures.

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555 Timer-Ramp Generator

Ramp Generator Circuit-using 555 Timer IC

We know that if a capacitor is charged from a voltage source through a resistor, an exponential waveform is produced while charging of a capaci­tor from a constant current source produces a ramp. This is the idea behind the circuit. The circuit of a ramp generator using timer 555 is shown in figure. Here the resistor of previ­ous circuits is replaced by a PNP transistor that produces a constant charging current.

Ramp Generator Circuit

Charging current produced by PNP constant current source is

i_C = Vcc-V_E / R_E

where V_E = R₂ / (R1 + R2) * V_CC + V_BE

When a trigger starts the monostable multivibrator timer 555 as shown in figure, the PNP current source forces a constant charging into the capacitor C. The voltage across the capacitor is, therefore, a ramp as illustrated in the figure. The slope of the ramp is given as

Slope, s = I/C

Positive voltage to negative voltage converter

Description.
This circuit diagram shows how to obtain a negative voltage from a positive voltage supply. Another advantage of this circuit is that, the negative voltage together with the original positive supply can be used to simulate a dual supply. The circuit is based on timer IC NE555. The NE555 is wired as an astable multivibrator operating at around 1 KHz. The square wave output if available at pin no 3 of the IC. During the positive half of the square wave, capacitor C3 charges through diode D2.When the output of IC is at zero the C3 discharges through diode D2 and the capacitor C4 gets charged. As a result of this the voltage at the junction of the anode of D1 and cathode of C4 will be always negative with respect to the ground.
Circuit diagram.

Notes.

• Assemble the circuit on a Vero board.
• The IC1 must be mounted on a holder.
• C3 and C4 must be rated at least 25V.
• Do not connect loads that consume more than 50mA current.
• The negative voltage output will be always a few volts lower than the positive supply.

High voltage generator circuit

Description.
First of all let me remind you that this circuit is a very dangerous one. The output voltage of this circuit is in Kilo volts and it can seriously injure you or kill you. Try this circuit only if you have enough experience dealing with high voltages. I have no responsibility on any hazards caused by the circuit. Be very careful. This is a humble request.

The circuit given here has three sections namely oscillator, switching stage and a step up stage. The oscillator is build around a NE555 timer operating at 25 KHz. The output of the NE555 coupled to the base of the power transistor TIP3055 which is the switching device. The power transistor drives primary of the step up transformer at 25 KHz and as a result a high voltage will be induced across its secondary.
Circuit diagram.

Notes.

• A 12V lead acid battery can be used for powering the circuit.
• TIP3055 must be mounted on a heat sink.
• T1 can be an EHT (extra high tension) transformer used in television sets.
• For an EHT from 20inch TV, the output voltage will be 8 to 10 KV @12V supply voltage.
• This circuit is not an efficient one and is not suitable for any serious applications.
• Once again, be very careful with this circuit!.

Description.
First of all let me remind you that this circuit is a very dangerous one. The output voltage of this circuit is in Kilo volts and it can seriously injure you or kill you. Try this circuit only if you have enough experience dealing with high voltages. I have no responsibility on any hazards caused by the circuit. Be very careful. This is a humble request.

The circuit given here has three sections namely oscillator, switching stage and a step up stage. The oscillator is build around a NE555 timer operating at 25 KHz. The output of the NE555 coupled to the base of the power transistor TIP3055 which is the switching device. The power transistor drives primary of the step up transformer at 25 KHz and as a result a high voltage will be induced across its secondary.
Circuit diagram.

Notes.

• A 12V lead acid battery can be used for powering the circuit.
• TIP3055 must be mounted on a heat sink.
• T1 can be an EHT (extra high tension) transformer used in television sets.
• For an EHT from 20inch TV, the output voltage will be 8 to 10 KV @12V supply voltage.
• This circuit is not an efficient one and is not suitable for any serious applications.
• Once again, be very careful with this circuit!.

Read more: http://www.circuitstoday.com/high-voltage-generator-circuit#ixzz1eSZQJ64p
Under Creative Commons License: Attribution

Function Generator Circuit

Function Generator Circuit

Description.

The ICL8038 is a function generator chip, capable of generating triangular, square , sine, pulse and sawtooth waveforms . From these sine, square & triangular wave forms can be made simultaneously.There is an option to control the parameters like frequency,duty cycle and distortion of these functions.This is the best function generator circuit for a beginner to start with and is of course a must on the work bench of an electronics hobbyist.The circuit here is designed to produce waveforms from 20Hz to 20 kHz.The ICL 8038 has to be operated from a dual power supply.

Function Generator Circuit Diagram & Parts List.

Function Generator Circuit Diagram

Notes .

• The circuit needs a dual power supply. A +15 -15 power supply as shown in the circuit is enough for the purpose.
• The frequency of the output wave form can be adjusted using R7.It must be a 100K Log POT.
• The duty cycle can be adjusted using R3 , a 1K POT.
• The distortion of the wave form can be adjusted using R5 , a 100K POT.
• Square,triangle & sine waveforms can be obtained simultaneously at pins 9,3,2 respectively.

Op-amp Circuits

Op-amp

CircuitsToday.com is listing some of the best op-amp circuits present in our sites. There are more than 20 circuits which show the different applications of the op-amp. We are listing the links of our best 15 circuits with detailed descriptions and circuit diagrams. Do not forget to go through the comments section for each post, from where you will get ideas about how to modify the circuit. Also if you have any doubts, feel free to ask them through comments.

Before going into detail about the different op-amp application circuits, it is important to know about the basics of op-amp, and the small applications of the IC. To learn about it click on the link – Operational Amplifiers (Op-amps)

The above linked article contains all the basics of op-amps, with the basic op-amp circuit with two transistors. The different advantages of op-amps are also specified, along with links to different basic op-amp circuits like Comparator Circuit, Schmitt Trigger Circuit, Astable Multivibrator, Monostable Multivibrator, Zero-crossing detector, voltage splitter and so on. The article also contains information about the 741 IC, its packaging style, the use of op-amp as an inverting and non-inverting circuit, and so on. The different pin assignments of the 741 IC are also explained with neat figures.

Given below are some links to some of the best op-amp based circuits designed by us. Most of them are simple and easy to make a home. We have given a very detailed description and circuit diagram for every one of the.

1.  Sensitive Intruder Alarm Circuit

In this circuit, apart from the 741 op-amp IC, a Light Dependent Resistor (LDR) is also used. The main use of the LDR is to sense the presence of a person through his shadow falling on the sensor. As soon as the shadow falls on it, the resistance of the device begins to increase. A 555 timer IC is also used to be triggered by a transistor and thus to drive the alarm load. Read more about the working of the circuit from the link above.

2. Transistor Amplifier Circuit-12 Watts

This circuit is very simple and inexpensive. Only one uA741 op-amp and four transistors are required for the working of this circuit. The op-amp produces the gain required and the transistors are connected to work as the speaker driver. The circuit is highly stable and is also known to produce a reasonable output of 12 Watts on a 4 Ohm speaker.

3. Sound Operated Flip Flop

This circuit is used to toggle the output pins status of a flip-flop IC, using a sound. The op-amp used here is the IC LM324. Two op-amps from the chip are selected and are used to amplify the sound picked by the condenser microphone. The third op-amp inside the IC is used as a level detector. The flip-flop IC used here is the IC CD4027.

4. Sound Pressure Meter

The op-amp used here is called CA 3140. The op-amp is connected as a non-inverting amplifier, and can be easily setup as a sound level checker at homes and theatres. You will find it very useful in checking the sound pressure of each channel on different positions of the room.

5. Infrared Motion Detector Circuit

This circuit is used to produce an alarm as soon as an intruder walks across the infrared rays produced by an IR diode. A 555 timer IC is also used here to work as an astable multivibrator. The beams produced by the IR diode are received by a photo-transistor. When an intruder walks by, the LM 1458 op-amp senses the difference in phase and automatically goes high.

6. Passive Tone Control Circuit

The circuit uses op-amp as the only active element, whereas all the other components are passive elements. Thus, the circuit got its name as Passive Tone Control Circuit. The circuit is divided into two parts – the op-amp based pre-amplifier and the Baxandall tone control circuitry. The op-amp used here is the TL072 IC. The Baxandall circuit principles and the whole circuit is explained in detail in the original article. This circuit does have some disadvantages like energy wastage, and high distortion.

7. Active Crossover Circuit

This circuit can be considered just the opposite of the passive tone control circuit. All the drawbacks that the passive circuit has is rectified by this circuit. They are known to be more suitable for HiFi audio systems. The circuit divides the complex audio signal into two bands, one being the low frequency signal, and the other being the low frequency signal. These two signals are further amplified separately and is bi-amped to its corresponding low frequency and high frequency bands. The op-amp used here is the LM833 IC, which is basically a dual op-amp that is designed for audio purposes.

8. Car Subwoofer Filter

This circuit finds a lot of applications in the use of automobile subwoofers. The circuit is basically a low pass filter whose pass frequency lies between 60 hertz and 160 hertz. The op-amp used in this circuit is called the TL072 dual BIFET op-amp IC. The chip has two op-amps. One of them is connected as a buffer, and the other is connected as a low-pass filter.

9. Low-pass Filter for Subwoofer

The IC used here is the TL062 IC. It is basically a dual high input impedance JFET op-amp. It is known for its good audio characteristics. The circuit description and diagram is available in the main article. 3-Input Microphone Preamplifier

The op-amp used here is the IC LM348, due to its unique properties like high gain, internally compensated quad-operational amplifier with a class AB output stage, low input supply drain current, and so on. The IC is to be powered with the help of a dual power supply. Four of them are used in this circuit.

10. 3-Way Active Crossover Network

This circuit finds wide applications in audio amplifier systems. The op-amp used here is called LF353 IC, which was developed by National Semiconductors. The IC is a dual JFET op-amp internally compensated input offset voltage.  The op-amp is also known for its low offset currents, high bandwidth, and low input bias currents due to the JFET based input stage. Two of them are used in this circuit. One of them is used to buffer the input audio signal, and the other is used to handle the three bands of the audio namely bass, mid-range, and treble. To know more about the circuit, click on the link above.

11. Audio Line Driver

In this circuit, an op-amp called TSH22 IC, developed by ST Microelectronics is used. At a high level of modulation, and with a bandwidth of 25 Mega Hertz, the IC is known to drive medium impedance loads with low distortion and high output current.

12. Subwoofer Filter

The circuit diagram of a subwoofer filter with the help of op-amps is given in the article above along with a detailed description. The circuit consists of 10 op-amps. The circuit needs a low pass filter with a cut-off frequency of 200 hertz, as the audio frequencies below the value are known to be in the subwoofer range. The circuit may look a little complex, but after reading the working of the circuit, you will find that it is quite simple. A potentiometer is also required to couple one of the inverting inputs of the op-amp. You can use an LED if needed, and it is optional.

13. Preamplifier for Dynamic Microphones

This circuit is known to be a low noise pre-amplifier suitable for dynamic microphones. The op-amp used here is called uA739, manufactured by Fairchild Semiconductors. Such an op-amp is known to be famous for its high gain and excellent stability. The IC package contains two op-amps, but only one of them is used for the circuit.

A capacitor is also used in the circuit to provide DC de-coupling.  The audio signals from the microphone are coupled to the non-inverting input of the op-amp. A resistor-capacitor network is also connected in the circuit. This network helps in bypassing the unwanted high frequency signals that comes from the microphone. This circuit is highly applicable in audio circuits as it can handle a wide range of signals. To learn more about the circuit, click on the link above.

14. 3 Input Mic Mixer Circuit

In this circuit, 4 op-amp 741 IC’s are used. Out of them three of them are designed to work as pre-amplifiers and the fourth is connected as a summing amplifier, which adds the signals from the output of the three pre-amplifiers. The three pre-amplifiers produce a gain of about 40dB to the individual input signals. The summing amplifier produces a gain of about 5dB to the final output signal. Thus the total gain of the circuit comes around 45dB.

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