The schematic diagram shown right here is the automatic switching-on emergency light circuit which is controlled using IC. The most important capabilities of this circuit are: automatic switching-on of the light on main power failure and battery charger with overcharge protection.

When mains electrical power is absent, relay RL2 is in deenergised state, feeding DC source from battery to inverter section via its N/C contacts and switch S1. The inverter section comprises IC2 (NE555) that is applied in stable mode to generate sharp pulses / wave with frequency of 50 Hz to drive the power MOSFETs. The output of IC3 is fed to gate of MOSFET (T4) directly while it is applied to MOSFET (T3) gate just after inversion by transistor T2. Therefore the power amplifier designed close to MOSFETs T3 and T4 functions in push-pull mode.

The output across secondary of transformer X2 can simply drive a 230-volt, 20-watt fluorescent tube. In event light isn’t needed to become on during mains power failure, then just flip switch S1 to off position.

Battery overcharge preventer circuit is designed close to IC1 (LM308). Its non-inverting pin is held at a reference voltage of about 6.9 volts that is obtained implementing diode D5 (1N4148) and 6.2-volt zener D6. The inverting pin of IC1 is connected to the positive terminal of battery. Thus when mains electric supply is present, IC1 comparator output is high, unless battery voltage exceeds 6.9 volts. So transistor T1 is normally forward biased, which energises relay RL1. Within this state the battery stays on charge via N/O contacts of relay RL1 and current limiting resistor R2. When battery voltage exceeds 6.9 volts (overcharged condition), IC1 output goes low and relay RL1 gets deenergised, and thus stops more charging of battery.

MOSFETs T3 and T4 may be mounted on appropriate heat sinks to prevent overheating on the MOSFETs and keep the MOSFETs in good performance.

This automatic switching-on emergency light circuit taken from EFY magazine. The circuit is already tested and should be working properly. This circuit idea available in PDF document, download from the following link:

Automatic Emergency Light Project

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Here the project report of DC/AC pure sine wave inverter. This report focuses on DC to AC electrical power inverters, which aim to efficiently transform a DC power source to a high voltage AC supply, just like electrical power that would be presented at an electrical wall outlet. Inverters are utilised for a lot of applications, as in conditions where low voltage DC sources such as batteries, solar panels or fuel cells have to be converted in order that electronic devices can run off of AC power. One instance of such a situation would be converting electrical electrical power from a vehicle battery to run a laptop, Television or mobile phone.

The process in which the low voltage DC power source is inverted, is completed in two steps. The very first being the conversion of the low voltage DC power to a high voltage DC source, and the second step being the conversion of the high DC source to an AC waveform applying pulse width modulation. A further technique to accomplish the preferred outcome would be to first convert the low voltage DC power to AC signal, and after that use a transformer to increase the voltage to 120 volts. This project concentrated on the first method described and specifically the transformation of a high voltage DC power source into an AC output.

Of the various DC-AC inverters in the marketplace nowadays you will find primarily two different forms of AC output produced: modified sine wave, and pure sine wave. A modified sine wave could be seen as more of a square wave than a sine wave; it passes the high DC voltage for specified amounts of time so that the average electrical power and rms voltage would be the exact same as if it were a sine wave. These kinds of inverters are considerably cheaper than pure sine wave inverters and therefore are attractive options.

Pure sine wave inverters, alternatively, generate a sine wave output identical to the power coming out of an electrical outlet. These devices are capable in running more sensitive devices that a modified sine wave may possibly lead to damage to such as: laser printers, laptop computers, power equipment, digital clocks and medical gear. This form of AC power also reduces audible noise in devices such as fluorescent lights and runs inductive loads, like motors, faster and quieter because of the low harmonic distortion.

This project report of DC/AC Pure Sine Wave Inverter will give you the below sine wave:

Complete project report about DC/AC pure sine wave inverter can be download here:

DC/AC Pure Sine Wave Inverter PDF Document

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Here the simple Mini UPS circuit diagram. This circuit can provide an uninterrupted power supply (UPS) to operate 12V, 9V and 5V DC-powered instruments at up to 1A current. The backup battery will take up the load with no spikes or delay when the mains electrical power gets interrupted. It could possibly also be utilized as a workbench power supply that delivers 12V, 9V and 5V operating voltages. The circuit instantly disconnects the load when the battery voltage decreases to 10.5V to avoid deep discharge of your battery. LED1 indication is presented to indicate the complete charge voltage level of the battery. Miniature white LEDs (LED2 and LED3) are utilized as emergency lamps especially during electrical power failure at night time.

A common step-down transformer delivers 12V of AC, that is rectified by diodes D1 and D2. Capacitor C1 features ripple-free DC to charge the battery and to the remaining circuit. When the mains electrical power is on, diode D3 gets forward biased to charge the battery. Resistor R1 limits the charging current. Potentiometer VR1 (10k) with transistor T1 acts as being the voltage comparator to indicate the voltage level. VR1 is so adjusted that LED1 is in the “off” mode. when the battery is completely charged, LED1 glows indicating a maximum voltage level of 12V.

When the mains power fails, diode D3 gets reverse biased and D4 gets forward biased so that the battery can automatically take up the load without any delay. When the battery voltage or input voltage falls below 10.5V, a cut-off circuit is used to prevent deep discharging of the battery. Resistor R3, zener diode ZD1 (10.5V) and transistor T2 form the cut-off circuit. When the voltage level is above 10.5V, transistor T2 conducts and its base becomes negative (as set by R3, VR2 and ZD1). But when the voltage reduces below 10.5V, the zener diode stops conduction and the base voltage of transistor T2 becomes positive. It goes into the “cut-off” mode and prevents the current in the output stage. Preset VR2 (22k) adjusts the voltage below 0.6V to make T2 work if the voltage is above 10.5V.

When power from the mains is available, all output voltages12V, 9V and 5Vare ready to run the load. On the other hand, when the mains power is down, output voltages can run the load only when the battery is fully charged (as indicated by LED1). For the partially charged battery, only 9V and 5V are available. Also, no output is available when the voltage goes below 10.5V. If battery voltage varies between 10.5V and 13V, output at terminal A may also vary between 10.5V and 12V, when the UPS system is in battery mode. Outputs at points B and C provide 9V and 5V, respectively, through regulator ICs (IC1 and IC2), while output A provides 12V through the zener diode. The emergency lamp uses two ultra-bright white LEDs (LED2 and LED3) with current limiting resistors R5 and R6. The lamp can be manually switched “on” and “off” by S1.

The mini UPS circuit is assembled on a general purpose PCB. There is adequate space between the components to avoid overlapping. heat sinks for transistor T2 and regulator ICs (7809 and 7805) to dissipate heat are used.

The positive and negative rails should be strong enough to handle high current. Before connecting the circuit to the battery and transformer, connect it to a variable power supply. Provide 12V DC and adjust VR1 till LED1 glows. After setting the high voltage level, reduce the voltage to 10.5V and adjust VR2 till the output trips off. After the settings are complete, remove the variable power supply and connect a fully-charged battery to the terminals and see that LED1 is on. After making all the adjustments connect the circuit to the battery and transformer. The battery used in the mini UPS circuit is a 12V, 4.5Ah UPS battery.

This circuit is basically a 8W inverter circuit. The? circuit continues to be intended to drive an 8W fluorescent lamp from a 12V power supply, utilizing an cheap inverter primarily based on a ZTX652 transistor.

The inverter will operate from supplies in the variety of 10V to 16.5V, obtaining efficiencies up to 78% as a result causing it suitable for use in on-charge devices like as caravans / mobile homes / RVs and also periodically charged devices like as roadside lamps, camping lights or outhouse lights etc. Other capabilities on the inverter are that it oscillates at an inaudible 20kHz and that it contains reverse polarity protection.

Download the 8W fluorescent lamp inverter application note:
? Download Link

Download the ZTX652 datasheet:
? Download Link

This is the power inverter circuit based MOSFET RFP50N06. The inverter capable to handle loads up to 1000W, it’s depended on your power inverter transformer. The RFP50N06 Fets are rated at 50 Amps and 60 Volts. Heatsink is required for cooling the MOSFETs. You may add some MOSFETs with parallel connection to get more power. It is recommended to have a “Fuse” in the Power Line and to always have a “Load connected”, while power is being applied.

The advantages of this inverter circuit:

• Can be used with a wide range of supply voltages by using appropriate transformers.
• Can be used to deliver a wide range of output voltages by using appropriate turns ratio.
• Output Frequency is Adjustable and Stable.
• A Standard Step Down transformer (Reverse connected) can be used with Fair Results for Lower Wattages.
• With the addition of “Parallel Output Fets” and a Large Transformer, Power can be GREATLY Increased.

100W Power Inverter Notes

This circuit will provide a very stable “Square Wave” Output Voltage.

Frequency of operation is determined by a pot and is normally set to 50 or 60 Hz, Depends on where you live.

SOME “off the shelf” transformers can be used, but with Poor Results. Or you can Custom wind your own FOR BEST RESULTS.

Additional MosFets can be paralleled for higher power.

It is recommended to Have a “Fuse” in the Power Line and to always have a “Load connected”, while power is being applied.

The Fuse should be rated at 32 volts and should be aproximately 10 Amps per 100 watts of output.

The Power leads must be heavy enough wire to handle this High Current Draw!

Appropriate Heat Sinks Should be used on the RFP50N06 Fets. These Fets are rated at 50 Amps and 60 Volts.
** Other types of Mosfets can be substituted if you wish.

The LT1013 offers better drive that the LM358, but its your choice.

The Power transformer must be capable of handling the chosen wattage output. Also, Appropriate Heat Sinks are Necessary on the Mos-Fets.

Using a rebuilt Microwave transformer as shown below, it should handle about 500 watts Maximum. It requires about 18 turn Center-Tapped on the primary. To handle 500 watts would require using a 5 AWG wire. Pretty Heavy Stuff, but so is the current draw at that power.

Simplified Operation is: IC1A & IC1B, Along with IC2A & IC2B and the Transistor form a Voltage controlled Oscillator of which the frequency is adjusted with the 25K ohm pot. IC2C & IC2D are buffers, driving the Mos-Fets, out of phase of each other.

The 13 volt Zeners stabalize supply voltages and limit signals, while the 36 volt Zeners limit spikes from the transformer.

1000W Power Inverter PCB Layout Design:

1000W Power Inverter circuit source: chemelec.com

Inverter Diagram:

The Q1 and Q2 used generate square wave. Q5-Q8 amplify the signal and the transformer to increase the AC/square wave current from 12VAC to 220V AC 50HZ.

Inverter PCB layout:

The following image is the bottom/copper PCB layout and to layout for the components placement. You may use universal PCB veroboard to make it easier.

Inverter circuit is typically used for emergency lighting, since the power output is small, which is about 5W only. But you can use this inverter for other purposes that do not require large electric power such as mobile phone charger, small lamp/LED lamp, etc. Don’t use this circuit for electronic appliances which consume high power, of course it will not works.

You may use 12V lead acid battery for this circuit.

5W simple inverter circuit source:
http://skemarangkaian.com/5w-simple-inverter-circuit-with-2n3055/

The first section of the 555 timer is wires as an astable oscillator with R2 and C1 setting the frequency. The output is available at pin 5. The second section is wired as a phase inverter. That output is available at pin 9. Resistor R3 and R4 keep output transistor Q1 and Q2 from loading down the oscillator.

The two transistors drive the transformer push-pull fashion. When one transistor is biased-on, the other is cut-off. The transformer is a 120V/18V center tapped that is connected backwards, so that is steps the voltage up rather than down. Oscillator circuit U1, R1, R2 and C1 operates from about 4 to 6V with very stable output.

This document will show you the basic theory of DC to AC inverters, about the circuit’s works, the calculation to build DC to AC inverter and more. The sample of inverter circuit diagram also included in this document.

INTRODUCTION

Transistor dc to ac inverters are useful in a wide variety of applications. They power the complicated electronic systems of orbiting satellites and cool astronaut’s suits. They are widely used to operate gyros and other airborne instruments. They provide AC power to operate the electric shaver in your car. Inverters may become increasingly important and widely used with the further development of economic low voltage DC power sources such as solar cells, nuclear cells, fuel cells, etc.

It should be noted that rectifications of the inverter output results in DC to DC convertion. Transistor inverters as described here in are, therefore, the “heart” of transistor DC to DC converters. However, when used as converter, to provide rectified output the frequency and waveshape of the transistor circuit are unimportant, except as they relate to the efficienty and smoothing of the rectified output.

Download the document of Basic Theory of DC to AC Inverters:

The ABC's of DC to AC Inverters

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In the circuit diagram we can observe that 12V battery is connecter to the diode LED and also connected to the pin8 of the IC 4047 which is VCC or power supply pin and also to pin 4 and 5 which are astable and complement astable of the IC. Diode in the circuit will help not give any reverse current, LED will work as a indicator to the battery is working or not.

IC CD4047 will work in the astable multivibrator mode. To work it in astable multivibrator mode we need an external capacitor which should be connected between the pin1 and pin3. Pin2 is connected by the resistor and a variable resistor to change the change the output frequency of the IC. Remaining pins are grounded .The pins 10 and 11 are connected to the gate of the mosfets IRF540. The pin 10 and 11 are Q and ~Q from these pins the output frequencies is generated with 50% duty cycle.

The output frequency is connected to the mosfets through resistor which will help to prevent to the loading of the mosfets. The main AC current is generated by the two mosfets which will act as a two electronic switches. The battery current is made to flow upper half or positive half of the primary coil of transformer through Q1 this is done when the pin 10 becomes high and lower half or negative half is done by opposite current flow through the primary coil of transformer, this is done when pin 11 is high. By switching the two mosfets current is generated.

This AC is given to the step up transformer of the secondary coil from this coil only we will get the increased AC voltage , this AC voltage is so high; from step up transformer we will get the max voltage. Zenor diode will help avoid the reverse current.

Warning!: Lethal potential at the output of transformer, please be careful, enclose this power inverter circuit into the plastic box.