230V automatic light bulb circuit

 

The automatic light circuit describe here is a simple 220V automatic circuit which is very easy to construct and very few components are used which are supper cheap. The main component of this circuit is the versatile 555 timer IC which is used in most electronics projects for timer control function.

This circuit works on the day light or the sun light first ray. It will wake you up when first ray of sun light falls on the sensor of the circuit. The circuit can control any light of your choice like simple and old incandescent light, cfl, florescent, mercury light or led ligh which is under 5A and 220V rating. The relay used in this circuit if of 5A rating. You can use heavy contacts relay also for driving more loads and heavy ampere usage.

The circuit construction is easy enough. This circuit can be constructed both on pref board or on specially made PCB. The PCB pattern and components layout will be given latter on this page. The circuit comprise of IC 555 timer, one bridge rectifier, a zener diode of value 12V 400mw, PC817A Optoisolator, a flywheeling diode, an LDR as light sensor and a few small resistors and capacitors. A relay is used as output load driver. The relay is a single pole and single through type. Anyhow you can use any type of relay according to your requirements. The circuit has a wide voltage range. The power supply depends upon the relay voltage and other components values. 12V power feed could ideal for this circuit as 12v DC relays are very commonly available and they are cheap as they are frequent used in most customer electronics.

555 IC timer based automatic lighting circuit

The circuit schematic above shows that the day and night sensor here is one LDR from LG company which is GL5528. LDR is the light dependent resistor. You can use any other equivalent LDR too if the same number is not available easily to you. The LDR here makes a potential devider circuit with combination to R2 resistor which is 100K. Through R3 resistor the variable voltage from the junction of this voltage devider is fed to the junction of of pins 2 and 6 of the timer IC 555. Timer IC 555 is controlling the relay PL1.

The circuit function in the way that when the input to the IC exceeds 8.1V then the output pin of the IC number 3 becomes low and current flows through the relay. And when the input to the IC from the voltage devider circuit is below 4.1V the IC output pin 3 becomes high and there is no current flow through relay. Hence relay becomes off.

Light bulb is connected to the relay in the way that the relay contacts are coming in series to one wire of the light bulb. So when the contacts closes, the light glow and when the contracts opens, the light bulb become dark. There in no other connection of the light bulb to any other part of the circuit. The light bulb is a 220V ac mains device and such voltage are not fed inside the circuit.

For powering up the circuit capacitor type doping power supply is used. This arrangement is especially made to make it supper cheap and to conserve the space on the circuit board. As the intention is to fix this circuit in light bulb holder. You can use any transformer type or switch mode type power supply of your choice. As these capacitor dropping type power supplies are simple but they are not such promising.

What is a miniature circuit breaker or MCB

Miniature circuit breaker or MCB is an electrical protection device which cuts off electric circuit from power source during short circuit. During short circuit the circuit draws abnormally high current which can cause fire or other damage. To avoid such damage it is a must to isolate the shorted circuit from the rest of the power system or the power source. A miniature circuit breaker acts like an automatic fuse. In older days fuse was used in electrical system to protect the circuit. Whereas in today's modern installations circuit breakers are used in place of fuse. Fuse has the same function but it could not be switched on back after tripping once it broke. It requires to replace the whole burned fuse or to rewire it in case of re-wire-able fuse. Whereas in case of miniature circuit breaker, it could be reset after short circuit repair like a switch. The reset time is way too less for a miniature circuit breaker compared to a fuse repair or replacement. MCB or miniature circuit breaker is frequently used in latest installations and wiring. Some people think that miniature circuit breaker or MCB is more sensitive than a fuse. But this is not the reality. In reality the fuse is way too sensitive then miniature circuit breaker or mcb and a fuse works in almost all conditions. But in some special cases like in elcb or earth leakage circuit breaker. In case of earth leakage circuit breaker it provides a special feature of protection which a fuse can't provide. The research says that it needs half a cycle time of ac wave form to blow a fuse whereas a miniature circuit breaker needs one complete cycle or even more to trip it and to isolate the circuit. Anyway miniature circuit breaker is still the best choice of protection.

How MCB or miniature circuit breaker works

There are two types of trip arrangements in MCB or miniature circuit breaker. First is bimetallic temperature trip and second is electromagnetic trip. If high current or over current flows through bimetallic strip, it bends due to over temperature. A mechanical latching mechanism is attached to the bimetallic strip. The bend of bimetallic strip releases the latch. The mechanical latch is further attached to the tripping mechanism of the circuit breaker. The release of the latch cases to trip the circuit breaker and opens the contact and isolate the circuit attach to it. The other way is opening the contacts by electromagnetic force. When high current flows through the mcb, the electromagnet inside the mcb becomes stronger and attracting the plunger inside. The plunger is attached to the latch. the attraction of the plunger releases the latch and in this way the tripping mechanism of the circuit breaker is activated to the circuit breaker tirps and isolates the defective circuit from the power source.

MCB is designed to use and is not repaired if it is going defective. Normally they are thrown and replaced when they become defective. The replacement of the mcb is easy and it takes less time to replace. There are two types of protections inside an mcb. It provides protection against short circuit as well as against overloading. The electromagnet part provides protection against short circuit and the bimetallic part provides protection against overloading.

TDA2822 wonderful small and simple audio amplifier

This tutorial will guide you making the most simple and low power audio amplifier comprised of single IC TDA2822. TDA2822 is sometimes refereed as TDA2822M and sometimes simply 2822. This IC provides small power of about 2W per channel from a 5V power source. The power supply is wide range for this chip from 3V to 20V. The wide range of power supply, circuit simplicity, less external components and low price makes this chip ideal for most small application. This TDA2822 is a versatile audio amplifier chip having 8 pin dual inline package and is used frequently in audio Cassatt players, radios, small stereos, PC speakers, telephones and many more applications. This audio amplifier is capable of producing good quality audio with very low distortion so that it could fill up a small room with music waves. This chip has a very low price and available very easily everywhere.

TDA2822M Stereo Amplifier Circuit

A simplified circuit diagram for such audio amplifier is shown below. The circuit consists of all necessary components for the amplifier requirement with this chip. The component count is so less that anyone having little experience with electronics can create such amplifier circuit.

In the above circuit all components like resistors, capacitors and variable volume controls are connected to different pins of the IC TDA2822M. There components are circuit requirements and they are used to control oscillations and positive feed back in the amplifier circuit. Such components are big in size and heavier so that they can't be constructed inside IC chip. Some chips known as hybrid contains such discrete components inside even. But as this IC chip is monolithic so components are located outside the chip.

Here in this circuit the audio input is provide to pin 6 and pin 7 trough volume controls or variable resistances which acts like atenuators for the audio signal and use to control the gain of the amplifier. Most of the time single shaft stereo type volume control is used in which there are two volume controls are constructed and a single shaft varies both volume controls. Out put to 4 Ohm speakers is provided through two 100UF 25V capacitors. They are AC coupling capacitors and avoid any DC to the speakers from the amplifier. The two inverting input pins pin 5 and 8 are connected together and they are connected to ground through a 1UF 25V electrolytic capacitor to avoid any positive feed back or oscillation in the circuit. At pin 2 of the IC 3V power supply positive is connected which is decoupled with a 10UF 25V capacitor. This capacitor should be located as close as possible to the chip to avoid harmonics and provide good filtration to the power line. Ground or negative terminal of the power is connected at pin 4 to the IC chip.

This circuit has an overall good performance but it is off course and old style class AB amplifier design on chip. New designs uses class D amplifier with great efficiency and less power consumption from battery. Such class D amplifiers is a new technology and are becoming popular in new audio designs for last few years. They are producing much less heat and their heat sink requirement is less and small heat sinks can even do for such amplifiers.

Here is the copper pattern for the pcb for this project. If you are going to do this project, this pcb pattern will help you a lot. This is especially important for university students. The following pcb layout will help identify components locations. The pcb layout is silk printed for this project. The silk print carries all necessary information regarding the whole circuit and project.

Smoke detector circuit

 A smoke detector circuit is one which is used to detect un-burned fuel smoke created due to burning process. Such circuits are useful for building safety and house hold safety requirements. Such circuits are compulsory in some countries to be installed in the buildings if you are going to build new building or house. Without such alarm circuit installation, the authorities would not pass your building and will now allow residents to live in such building due to fire hazards and lake of fire safety.

There are many kind of fire alarm circuit available in the market. Some uses special sensors and detectors to perform the job. Whereas some uses very basic sensors for such kind of job. The below circuit is also using a very basic concept and very basic circuit design for the purpose. It uses an LED and an LDR to detect smoke passing between both of them. This a must for this circuit to fix it in the path of smoke to pass the smoke between the led and ldr. Otherwise if smoke is not passing between led and lrd the circuit wouldn't detect the smoke and would not alarm in case of fire or smoke. Such circuit have a beauty that it is very simple and very low price and also is consuming very low power from the power supply or from the battery. There are some other kind of sensors available in the market which are a bit expensive and also they are consuming too much power form the power source. Such circuits details article would also be available here on this blog.

Smoke detector circuit using basic sensors and components

In the above circuit when smoke is passed between led and ldr, the ldr resistance changes due to change in the light intensity passes through the smoke. The ldr resistance decreases with more smoke. The would decrease the base current of the transistor. The transistor is connected here in this circuit in common collector configuration. Then the output of this transistor is fed to the cob IC which is a pre amplifier for the small signal received from the transistor. The first VR which is 100K in value under the ldr is used to calibrate the circuit. The output of the cob ic is fet to the ic2 which is a power amplifier and is TDA2002 though another VR which is also of 100K value. The output of the power amplifire IC TDA2002 is fed to the loud speaker which is of 8R impedance through a capacitor which is of 1000u and 25v value. The rest of the components resistance and capacitors are making filter network for the output of the audio power output IC TDA2002. The circuit is powered up from a 9V battery or a 9V PP3 battery. Power supply is off course better because battery would drain up with the passage of time. The other way is to use a rechargeable battery with appropriate charging arrangement to make the circuit battery powered and also free of battery replacement tension.

Industrial motors

Motors are very commonly used in industry. Motors are the work horses in industry. They are every where in industry and running different kind of loads in everyday life. They run fans, pumps, compressors, blowers, belt conveyors, elevators, spinners, rollers, mills, transmissions, agitators, vibrators, apron conveyors, kilns and spinners etc.

There are many kinds of motors. Among them 98% cases ac induction motors are used. There are two further kinds of induction motors. First and the most commonly used one is squirrel cage induction motor and the second one is off course wound rotor or slip ring induction motor. The squirrel cage induction motor is the most used on in industry from a fraction of Kw to a few Mw power rating. The other type wound rotor or slip ring induction motor is used to drive very high torque load and have ability to start very slowly under very high torque load and controls its current by resistance addition in the rotor circuit. The rotor circuit impedance is controlling the stater supplied current by transformer action. So the way to control the stater current is to insert impedance in the rotor circuit. For this purpose slip rings are used to bring the rotor power out of the motor on carbon brushes to outside circuit where impedance is introduced to limit the current in the motor starting condition. Latter on such impedance is reduced to zero or short circuit is created on the rotor circuit to insure maximum current flow through the rotor circuit hence maximum torque from the motor. Such motors are used to drive high inertia loads. Such loads examples are mills, gearboxes and huge fans.

There is another kind of ac motor used rarely in industry is synchronous motor. Synchronous motor is rarely used due to its complex construction and difficult starting procedure. Such motor have its special benefits which makes it unique for special purpose use. Those benefits are very high torque and this motor can run any power factor value. It acts like a synchronous capacitor. Meaning to say it is correcting the system power factor also if installed in industry. Also the other benefit is of-course running some mechanical load along with power factor correction.

There are DC motors used too in industry and in house hold use. In industry in older days such dc motors were very commonly used due their powerful torque and due to there speed control characteristics. As in older days frequency inversters or vfd were not invented to vary the induction motor, so DC motor was the only solution to achieve variable speed control.

BH1417 Stereo PLL FM Transmitter Circuit

Here is my YouTube video Hindi version about this circuit:

This BH1417 pll fm transmitter includes features like: pre-emphasis, sound limiter, stereo transmission, low pass filter, pll circuit, fm oscillator and rf output buffer. The sound limiter maintains the same audio level so no distorsions occur, the stereo encoder separates the left and right channel enabling stereo transmission, the low pass filter blocks any audio signal above 15 Khz to prevent rf interference and the pll circuit provides a rock solid frequency stability.

There are 14 possible transmission frequencies with 200KHz increments selected with a 4-DIP switch. Starts from 88.7 up to 89.9 MHz and 107.7 up to 108.9 MHz.

S4	S3	S2	S1	Frequency
1	1	1	1	88.7 MHz
1	1	1	0	88.9 MHz
1	1	0	1	89.1 MHz
1	1	0	0	89.3 MHz
1	0	1	1	89.5 MHz
1	0	1	0	89.7 MHz
1	0	0	1	89.9 MHz
1 = ON, 0 = OFF

Simply select transmission frequency at which you would like to transmit, set the combination for 4-DIP switch and BH1417 will tune to that frequency. If you can’t hear the transmitted audio signal on your FM receiver then re-adjust 2.5 turn variable coil until you can hear the signal.

Technical Specifications
Supply Voltage: 4 – 6V
Transmission Frequency: 87.7 – 88.9MHz, 106.7 – 107.9MHz (200kHz steps)
Output RF Power: 20mW
Audio Frequency: 20 – 15KHz
Separation: 40dB
Power Consumption: 30mA

Components

1x BH1417 – Stereo PLL Transmitter IC (Case SOP22)
1x 7.68 MHz Crystal
1x MPSA13 – NPN Darlington Transistor
1x 2.5 Turns Variable Coil
1x MV2109 – Varicap Diode
1x 4-DIP Switch
ANT – 30 cm of copper wire

1x 22K Resistor
7x 10K Resistor
1x 5.1K Resistor
2x 3.3K Resistor
1x 100 Ohm Resistor 1x 100uF Capacitor
3x 10uF Capacitor
2x 1uF Capacitor

1x 47nF Capacitor
3x 2.2nF Capacitor
1x 1nF Capacitor
1x 330pF Capacitor
2x 150pF Capacitor
1x 33pF Capacitor
2x 27pF Capacitor
1x 22pF Capacitor
2x 10pF Capacitor

Pyroelectric Infrared Sensor Module DIY Kit Anti-theft Circuit Sensor Module DIY Kits

Here is my video supporting this article:

Description of Home security system:
There are several home security systems out there. Different manufacturers use different techniques and topology in their design. Cameras are also very popular for the purpose of security. Main problem with security cameras is to monitor them. They have capability to record the view in DVR hard drive but they could not stop intruder from intrusion. They are just providing the proof after the incident happens. Whereas in most cases we want to stop an intruder from intrusion. for this purpose different types of alarming systems are developed which warns the intruders not to enter in a specific area. also these system are kind of passive systems which needs only power up and they stays in sort of sleeping mode when everything is normal. They activate an alarm at the time of intrusion. They don't normally need to observe. So such systems are better in the way that all the time monitoring is not needed. Monitoring all the time is not easy. It needs a team of three people minimum all the time to observe the cameras in 24 hours a day. In some very sensitive areas it is mandatory to keep system system in observation all the time but in normal situations an alarming system with no observation is the best choice. Such alarming systems use sort of activating sensing system which is activated by some parameter. mostly they use pyroelectric sensor which are activated by human body temperature. When a person is passing through the pir or piroelectric sensor, its body infrared radiation which is in the form of body temperature activates the pyroelectic sensor and it sends its output signal to an amplifier. The amplifier is amplifying the signal as well there is a timer operation also in the circuit. The amplifier activates a alarm which informs the intruder not to enter in the specific area as you are under observation.

Principle of operation:

1. When power is applied to the circuit, The pir sensor or piroelectric sensor senses human passed in front of it and it produces an electrical signal, the pir sensor output signal from sensor pin 2 is applied to one transistor VT1 and here it is amplified. Without amplification the signal is small enough so that it could not be fed to the next stage, then this signal is applied to the operational amplifier IC2A pin 3 which performed as high gain low noise amplifier stage, and latter the signal is supplied to IC1A for further amplification.
2.  The IC2B works like a voltage comparator and it compares the two inputs. One is the signal coming from the prvious stage and the other is the reference provided by R10 and VD1. Transistor VT is used to drive the output buzzer.