Build a Simple Emergency Light and Alarm Circuit Diagram

This Simple Emergency Light and Alarm Circuit Diagram is permanently plugged into a mains socket andNI-CD batteries are trickle-charged. When a power outage occurs,the lamp automatically illuminates. Instead of illuminating alamp, an alarm sounder can be chosen.When power supply is restored, the lamp or the alarm isswitched-off. A switch provides a “latch-up” function, in orderto extend lamp or alarm operation even when power is restored.Circuit operation:Mains voltage is reduced to about 12V DC at C2`s terminals, bymeans of the reactance of C1 and the diode bridge (D1-D4). Thusavoids the use of a mains transformer.

 Simple Emergency Light and Alarm Circuit Diagram

Trickle-charging current for the battery B1 is provided by theseries resistor R3, D5 and the green LED D6 that also monitorsthe presence of mains supply and correct battery charging.Q2 & Q3 form a self-latching pair that start operatingwhen a power outage occurs. In this case, Q1 biasing becomespositive, so this transistor turns on the self latching pair.

If SW3 is set as shown in the circuit diagram, the lampilluminates via SW2, which is normally closed; if set the otherway, a square wave audio frequency generator formed by Q4, Q5 andrelated components is activated, driving the loudspeaker.If SW1 is left open, when mains supply is restored the lamp orthe alarm continue to operate. They can be disabled by openingthe main on-off switch SW2.If SW1 is closed, restoration of the mains supply terminateslamp or alarm operation, by applying a positive bias to the Baseof Q2.

Notes:

Close SW2 after the circuit is plugged.Warning! The circuit is connected to 220Vac mains, then some parts in the circuit board are subjected to lethal potential! avoid touching the circuit when plugged and enclose it in a plastic box. 

Parts List
R1____________220K 1/4W Resistor
R2____________470R 1/2W Resistor
R3____________390R 1/4W Resistor
R4______________1K5 1/4W Resistor
R5______________1R 1/4W Resistor
R6_____________10K 1/4W Resistor
R7____________330K 1/4W Resistor
R8____________470R 1/4W Resistor
R9____________100R 1/4W Resistor

C1____________330nF 400V Polyester Capacitor
C2_____________10΅F 63V Electrolytic Capacitor
C3____________100nF 63V Polyester Capacitor
C4_____________10nF 63V Polyester Capacitor

D1-D5________1N4007 1000V 1A Diodes
D6______________LED Green (any shape)
D7___________1N4148 75V 150mA Diode

Q1,Q3,Q4______BC547 45V 100mA NPN Transistors
Q2,Q5_________BC327 45V 800mA PNP Transistors

SW1,SW2________SPST Switches
SW3____________SPDT Switch

LP1____________2.2V or 2.5V 250-300mA Torch Lamp

SPKR___________8 Ohm Loudspeaker

B1_____________2.5V Battery (tw1o AA NI-CD rechargeable cells wired in series)

PL1____________Male Mains plug

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parallel and series circuit diagrams

Some viewers hadnt clear idea about parallel and series circuits.Here you can see  we can  build a  circuit in two ways they are parallel and series.If I explain simply when you use series circuit it will reduce the light of the bulb according to the number of bulbs  but when you use parallel circuit diagram it will not reduce the light of the bulb but it will drain your battery speedly 
 

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Does not exist to bandwidth restrictions and limits the number of users

It is also the alternative solution for perfect cell phone jammer .
Operation of mobile TV technology. Core technology. For mobile TV technology, the very early abroad have begun to research. Japan in 1999 by a terrestrial broadcast digital television standard ISDB-T in Europe in 2002 began to study this standard, and in February 2004 by the DVB-H standard. South Korea in February 2003, clearly stated, "Digital Multimedia Broadcasting", and support standard named DMB, The country of Chinas mobile TV standard be introduced before the end of 2006. In October, the State Administration of Radio, Film and Television issued recommended standards: of STiMi technical standards. The formulation of these standards, to provide a basis for the development of mobile TV. It is for the supplementary installation method of perfect cell phone jammer on the outer wall.
At present, the core technology of mobile TV, is the network operator implementation. These technologies or standards, mainly in three ways: two-way communication that can use the mobile network, to provide users with personalized service; convenient right to business monitoring, management, accounting and control; do not change the phone hardware platform network bandwidth is limited, and could easily lead customers to compete for resources; low image resolution, image quality is affected by the impact of network bandwidth. Ground-based radio and television technology. Basically completed ready for commercialization. Does not exist to bandwidth restrictions and limits the number of users, high image quality; low sensitivity to the user, the capacity of the unexpected and emergency events. Usually there is no uplink, it is difficult to achieve the users personalized service. Adjust the distance between positions of installing perfect cell phone jammer .
Difficult to identify, control, interaction, billing and positioning services; terminal a digital television receiver unit must be increased. Have been commercialized for one year the use of satellites for mobile video broadcasting services more efficient; the satellites wide coverage. Personalized and interactive subject to certain constraints; terminal circuit module must be increased to be able to receive satellite TV signals. Based on the mobile communication network. In this way is actually through the mobile communication network using streaming media technology to achieve mobile TV program delivery, as well as the user on demand. The United States and Chinas mobile operators launched mobile TV services rely on the existing mobile network. Perfect cell phone jammer is hung inside the plant.

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Power Resumption Alarm and Low Voltage Protector

The circuit described here protects your electrical appliances like AC motors from damage due to low voltage at power-on. It remains standby without giving power to the load after power resumes. The load can be switched on only manually. This prevents damage to the device if it is on when power resumes.

unregulated power supply is derived from a 12V-0-12V, 300mA step-down transformer and rectifying diodes D2 and D3. The rectified DC is made ripple-free using capacitor C3. An audio/video indicator (piezobuzzer and LED3) is provided along with the power supply for power resumption.

When power is switched on, capacitor C4 charges through the piezobuzzer and LED3, making both of them active. The piezobuzzer beeps and LED3 glows for a few seconds. When capacitor C4 is fully charged, the cathode of the LED becomes high inhibiting further flow of current through the buzzer.

When the power is off, capacitor C4 discharges through resistor R9.

The circuit uses IC CA3140 (IC1) as a voltage comparator to detect voltage changes in the unregulated power supply due to AC mains. Mains voltage changes in the primary as also the secondary winding of the transformer, which is sensed by IC1 to energise/de-energise the relay. Zener diode ZD1 provides a reference voltage of 3V to make transistor T1 conduct. Preset VR1 adjusts the breakdown point of ZD1.

Fig. 1: Power supply circuit with resume indicator

When the voltage level is normal, zener diode ZD1 breaks down and transistor T1 is forward-biased. Capacitor C1 provides time delay of a few seconds to avoid any fluctuation affecting the device during power-on. When transistor T1 conducts, the inverting input (pin 2) of IC1 goes low. However, IC1 does not give a high output as its power supply depends on the conduction of SCR1 (BT169). So manual operation is necessary to energise the relay.

When push-to-on swish S1 is pressed, SCR1 fires to provide voltage to IC1 at its pin 7. As the voltage level at the non-inverting input (pin 3) of IC1 is half of the supply voltage, its output becomes high and the relay (RL1) energises. LED2 glows to indicate the high output of IC1 and activation of relay.

When the line voltage goes below 180V, the secondary voltage of the transformer also drops, say, below 12 volts, ZD1 cease to conduct and the collector of T1 becomes high. This high voltage at the inverting input (pin 2) of IC1 makes its output low. The relay de-energises to stop power to the device.

Fig. 2:  Low-voltage Protector Circuit Diagram

Assemble the circuit on a general-purpose PCB and enclose in a suitable cabinet. Use a 12V PCB-mounted relay. Provide holes for LEDs and switch S1 on the front side of the case. Connect AC power voltage to the motor (load) through the common and normally-open (N/O) contacts of the relay. After assembly and checking the circuit, switch on the circuit and wait for a few minutes. LED1 will gradually become bright due to the charging of capacitor C1. Press S1 to energise the relay. Adjust VR1 so as to make LED1 fully on. This will allow easy latching of the relay.

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How to Manufacture Automobile Electronic Parts and Earn a Handsome Income

To set up an auto electrical manufacturing unit, its important to have a thorough knowledge regarding the various technicalities associated with the field. The article makes a comprehensive approach and explains all the issues related to the subject. We begin with the basic raw materials and man power required for the intended installations and further proceed with the list of electronic parts that can be manufactured and sold in the relevant markets. The products that are included for the production are flasher buzzers, piezo buzzers, CDI units, musical horns, auto testing machine etc. How these can be made is also explained through discrete articles, linked in the sections.

Among most electronic products, the ones which are associated with automobiles are probably the largest selling types and are always in demand. Manufacturing these items and selling is surely a lucrative business. Here we discuss the procedures in details.

Today one thing that’s common with all of us is that we all want to earn money. However, with the population that’s ever growing, all sources of earning money have been captured, resulting in a cut-throat competition in every field. It’s feasible to make a way out from this intense competition only if you can manage an area where you are the master, and are able to create a monopoly.

The auto market today has become huge and with tremendous opportunities, but also it’s flooded with some tough competitors. Since vehicles cannot work without electricity and other associated electronic accessories, the products related to these have cropped up extensively and you can find a whole range of all sorts of electronic products, some of which are mandatorily used while some are just for decoration purposes. Whatever may be the seriousness of the application, electronic products have become today an integral part with all types of vehicles.

Thus, auto electronics is probably one such field where you can expect some good money, provided you are equipped with all the know-how required for the initial manufacturing set ups.

In this article we are going to discus the technical aspects required for setting up an auto electronic manufacturing plant for TWO-WHEELERS and THREE-WHEELERS, small though. However here we won’t discuss the legal procedures involved, like acquiring VAT number, CST number etc.

The following steps provide some crucial data regarding earning money by manufacturing auto electrical products:

What Electronic Products can be Manufactured for the Two-Wheeler Auto Market?

There are probably a host of them which you can choose from, or rather go for the entire range. Supplying or keeping the whole range will provide you with a better chance of fairing among the many vying vendors.

The items commonly associated with two/three wheelers are the side indicators, CDI units, rectifiers, buzzers, melody maker horn, etc.

To begin a manufacturing plant for producing the above auto electrical items, you would first want to acquire a space with a descent area; preferably a 20 by 40 sq ft will be ideal and sufficient to begin with.

You would also require fixing some furniture in the form of a long narrow table closely attached to the longer wall and a few number of chairs that can be accommodated. This set up is required for implementing the production process by lining up the workers so that the assemblies can be done in the most efficient manner.

The workers who would be responsible for assembling the electronic parts will need important and useful tools like the soldering iron, wire nipper, wire stripper, soldering paste, thinner etc. so all these must be procured in required numbers.

The engineers may require more sophisticated tools like multitester, desolder pump/wik, magnifying glass, power supply etc. along with the above mentioned tools. Procure all of these as per the requirements.

We are assuming that the workers required for carrying out the procedures would be appropriately employed, so we are not discussing how they can be contacted and interviewed etc.

After the initial set ups as discussed above are done, it’s time to select the items and chalk out the procedures plans. It would include the following points:

There should be at least one product that has the potentials to run through out the year, under all odds. Make it the base of your company’s production line.

  As an example you may select the buzzer unit, as it’s the easiest to assemble, finish, and sell, moreover the concerned raw materials are easily available. However this product may carry pretty low profit margins and you would need to sell tons of them to actually witness any significant income, but can be rest assured a steady flow of income through out the season.

The circuit of an electronic buzzer is discussed  HERE, it’s the simplest in design and widely used all across the world for automobile applications, especially in conjunction with side turn signal or flasher units.

The next type of selected product would be the one which sells like “hot cake” in the market, has reasonably less competition and has the potentials of providing fairly high profit margins.

You can assess the product and insist the engineers to do improvements in the form of cost cutting or adding new features into the product, so that it can stand out from the rest of the brands. This will give you an edge while introducing your product in the market.

A flasher with buzzer is one such item which satisfies the above conditions, I have already published an improved and low cost flasher buzzer circuit in Bright Hub – You can check it out  HERE.

  CDI units are another indispensable auto part which can be manufactured and sold with good profit margins. You can find it in Bright Hub, just type the relevant words in the given in-site Google search box.


You can refer this article to know how to make a two-three wheeler CDI circuit.

Having discussed the manufacturing process, testing these circuits for accuracy and reliability can become a crucial issue. A suitable auto part testing machine therefore becomes imperative, without which the whole set up may fail or jeopardize.

If you inquire about such a universal auto part testing machine, you would probably get it at very high costs. In Pune (India), Teckson Electronics has the monopoly of manufacturing these machines, and they charge an awful Rs.12000/- for each of them.

I investigated the mechanism and developed my own version at less than Rs. 600/- which is more efficient, and more reliable than the above unit. The complete design will be comprehensively discussed in one of my forthcoming articles.

That’s all what may be basically required and concludes the fundamental technical procedures involved with setting up an electronic auto part manufacturing unit.

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How to Build Toxic Gas Detector and Alarm Circuit with TGS813

The danger always exists, when the fuel gases such as propane or gas are confined to a small area. The alarm of toxic gases figs. 1-45 utilizes a tin-oxide-semiconductor. A coil of thin wire heated by a battery 12 V via IC1 and IC2, which pulses the voltage to the coil of the sensor, saving a significant amount of energy. Diode Zener Dl provides a constant voltage to the filament coil sensor. resistance of the sensor reduces the sensor is exposed to toxic gases such as hydrogen, carbon

Carbon monoxide and propane. To reduce the resistance of the sensor, the SCR gate voltage increases. When the gate threshold voltage is reached, the SCR fires and a buzzer alarm is activated. Once activated, the bell and the switch S1 should be used to reset the alarm. Since the sensor has a good deal of thermal inertia, S1 must be off or open for about three or four minutes after the initial activation, allowing the sensor to stabilize, thus avoiding false alarms. R7 sensitivity control set to the desired value, before the activation of SCR.

The toxic gas alarm is sensitive to less than 100 ppm of carbon monoxide. This alarm is useful for simple gas boats, sheds and cabins. You could save a life. Some of the companies listed in the Appendix to offer plans and kits for various toxic gas sensors.

Part List
Part Description
C1 0,01-MFD, 25-V capacitor (disc)
1 9-V zener diode D1 (NTE139A)
1 D2 4-V diode zener (NTE5068A)
1 SCR D3 (NTE5408)
1 Q1 Transistor 2N2222
U1 1 CD4013 CMOS flip-flop
1 U2 CD4049 CMOS Inverter Hex
1 siren piezo BUZ 6-9V
1 S1-TGS203 toxic gas sensor (Figaro or equivalent)

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Build a Positive And Negative Voltage Switching Supply

Build a Positive And Negative Voltage Switching Supply. An LT1172 generates positive and negative voltages from a 5-V input. The LT1172 is configured as a step-up converter. To generate the negative output, a charge pump is used. C2 is charged by the inductor when D2 is forward-biased and discharges into C4 when LT1172`s power switch pulls the positive side of C2 to ground. 

 Positive And Negative Voltage Switching Supply  Circuit Diagram

 

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Power Circuit Breaker – Operation and Control Scheme

Power Circuit Breakers (PCB) break an electrical circuit to isolate faults. They also re-close to make a circuit after the fault is removed. To enable this opening and closing, it is operated by either a remote relay or a local switch. A remote relay is located inside the control room while the switch is located inside the circuit breaker junction box.Close and Trip Circuit of a Breaker



Understanding a breaker scheme is important if you plan on designing a substation. Quite often, it is overwhelming to make sense of the entire scheme at a glance. The figure below depicting a circuit breaker scheme will be used to explain various elements of the PCB’s design and its control.

Forms of Contact
Before explaining what each device in the scheme does, understanding the different forms of contact is necessary. A form ‘a‘ contact represents a Normally Open (N.O.) contact while a form ‘b‘ is a Normally Closed (N.C.) contact. Thus when a breaker is de-energized, its 52a and 52b contact position stay true to the statement above and as shown in Figure 1. However, when PCB is energized, the contacts switch their state i.e. 52a contact will be closed while 52b is open. Contact positions of all other auxiliary relays and switches – remote or local – stay unchanged unless, ofcourse, they operate on a fault or other desired condition.

Circuit Breaker Trip Coil
Figure above depicts a trip coil of the breaker. For brevity, I will cover the trip coil no.1 with trip coil no.2 identical.
From the diagram, the breaker is fitted with a 43 switch that toggles between local trip and remote trip. Positioning it in local allows the persons at the breaker junction box to trip the circuit by closing the Control Switch (CS). Switching it to remote position permits the relays in the control house to close their contact and trip the breaker.
Modern PCB’s employing Sulfur Hexa-Flouride (SF6) gas to extinguish an arc are fitted with ANSI ’63′ relay. To prevent breaker damage due to flash-overs during low gas conditions, tripping of breaker is cut-out by this relay’s contact. Notice in Figure 1 how the contacts from this relay are strategically placed in the close and trip circuit to cut out any signal from the relays or switches.
At this point, the reader should realize the importance of contact development. All contacts operate only when the trip coil of their respective relay is energized. For instance, consider the 63 relay and its contacts shown in in figure 1. This relay is energized by the same DC source as the one supplying the breaker. However its trip coil is actuated by a transducer that can sense a fall in SF6 gas pressure. When this occurs, it switches its contacts located in different circuits to prevent any breaker operation. Similarly, the 27 undervoltage relay trip coil is connected across the DC source. When this supply is interrupted, the relay switches its contact position. This change can be relayed to an alarm or initiate some other action.
To trip the breaker from a remote location, all contacts from relays at the remote location shall be hard-wired. Yes, this means laying a lot of copper from the breaker cabinet to the relays. Further, all tripping contacts are wired in parallel. When either relay’s contact close and thus complete the circuit, the breaker trips.

Target Devices
Now, you may notice the red target lamp is connected in a way that will essentially short out the remote relays and trip the breaker. Not surprisingly, this is not the case. The target lamps shown in the scheme have enough resistance in them (~200 ohms), limiting the current that can energize the coil.
Target lamps are used in circuits to convey certain conditions. With the breaker closed and energized, the red lamp illuminates to indicate a live circuit. When the breaker opens (due to a fault) the green lamp illuminates – the circuit complete with 52b contact switching from open to close.
Most modern circuit breakers are specified with two trip coils. Energizing either one leads to breaker’s trip. Since a good amount of redundancy is built into the protection and control of a power system, it is not too uncommon to see all primary relaying in the system tripping trip coil 1 and the back-up tripping trip coil 2.

Circuit Breaker Close Coil
This coil when energized actuates a lever that engages the closing mechanism (like a spring). A close circuit is optionally fitted with both 43 local/remote switch and a local trip switch. Remote relays are wired in as shown in Figure 1. Unlike the trip circuit, the relay contacts in the close circuit are always connected in series and present in normally closed position. Thus, when a relay trips, it also blocks closing of the breaker. Until the relay is reset, either manually or remotely, the breaker will not be operational.

Anti-Pump Relays
To prevent inadvertent multiple closing operation, breakers are fitted with anti-pump relay. Assume a scenario where a fault persists on a line and a person is looking to close a breaker on it. Although the person presses the close button for a second or two, for the breaker which operates in cycles, this duration is an eternity. With the close button pressed, the breaker attempts to close but because of the fault in the system it trips again, then closes, then trips. This trip/close operation repeats for the second or two the button is pressed. Since the motor in the breaker is not rated for continuous duty, serious damage can occur to it.

Modern breaker control relays are programmed to check for synchronism and also to reclose a breaker. A single contact from this relay is all that is needed to initiate one-shot, two-shot, or three-shot scheme. In old breaker schemes, 25 relay contacts and reclosing relay (79) contacts are typically wired into the breaker close scheme.

On a final note, keep in mind that not all relays can handle the momentary trip/close coil currents. Auxiliary relays like an electro-switches are typically employed to handle these currents.

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Light and Dark Dependent Circuir

This is the circuit of a simple buzzer
that is activated by darkness, the buzzer is off when theres light and
on when it is dark. A general-purpose operational amplifier, the 741, is
used as a comparator that determines whether it is dark enough to turn on a self-oscillating piezoelectric buzzer.

Its inverting input is connected to a photoresistor,
a component whose resistance decreases as more light shines on it.  Its
non-inverting input, on the other hand, is connected to an almost fixed
voltage, i.e., a proportion of the supply voltage as set by timmer
resistor R2. 

 

Figure 1.  Darkness-Activated Buzzer Circuit Diagram.

            If there is ample light shining on the photo-resistor, the buzzer is quiet. As less light shines on the photo-resistor,
its resistance increases and causes the voltage across R1 to decrease. 
At a certain level of lighting, the voltage across R1, which is also
the voltage at the inverting input of the 741, becomes smaller than the
voltage at the non-inverting input. At this point, the 741 is triggered
to output a high level, turning on Q1.  Q1 then activates the
self-oscillating piezoelectric buzzer.

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