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This straight forward circuit will protect electrical appliances from over voltage as well as under voltage. The circuit also produces an alarm when the power supply comes back. An ideal circuit for home to protect your valuable equipments from voltage fluctuations. The same circuit with some modifications can be used  to make a automatic voltage stabilizer. High and Low Voltage Cut-Off with Delay and Alarm Circuit Diagram : When the mains voltage is in the normal level, the voltage at the negative terminal of zener diode D4 will be less than 5.6 Volts. At this condition transistor T1 will not conduct. The same time voltage at the negative terminal of zener diode D5 will be greater than 5.6 and so the transistor T2 will be conducting. The relay will be activated and the green LED will be glowing. When the mains voltage is higher than the set limit the transistor T1 becomes conducting since the voltage at the negative terminal of  D4 is greater than 5.6 V. At the same time transist...

This is the simple project of 4A High-Speed Low-Side Gate Driver circuit Diagram. The UCC27518 and UCC27519 single-channel, high-speed, low-side gate driver device is capable of effectively driving MOSFET and IGBT power switches. Using a design that inherently minimizes shoot-through current, UCC27518 and UCC27519 are capable of sourcing and sinking high, peak-current pulses into capacitive loads offering rail-to-rail drive capability and extremely small propagation delay typically 17 ns. The UCC27518 and UCC27519 provide 4-A source, 4-A sink (symmetrical drive) peak-drive current capability at VDD = 12 V. The UCC27518 and UCC27519 are designed to operate over a wide VDD range of 4.5 V to 18 V and wide temperature range of -40°C to 140°C. Internal Under Voltage Lockout (UVLO) circuitry on VDD pin holds output low outside VDD operating range. Features Low-Cost, Gate-Driver Device Offering Superior Replacement of NPN and PNP Discrete Solutions Pin-to-Pin Compatible With TI’s TPS2828 ...

The UCC27518 and UCC27519 single-channel, high-speed, low-side gate driver device is capable of effectively driving MOSFET and IGBT power switches. Using a design that inherently minimizes shoot-through current, UCC27518 and UCC27519 are capable of sourcing and sinking high, peak-current pulses into capacitive loads offering rail-to-rail drive capability and extremely small propagation delay typically 17 ns. The UCC27518 and UCC27519 provide 4-A source, 4-A sink (symmetrical drive) peak-drive current capability at VDD = 12 V. The UCC27518 and UCC27519 are designed to operate over a wide VDD range of 4.5 V to 18 V and wide temperature range of -40°C to 140°C. Internal Under Voltage Lockout (UVLO) circuitry on VDD pin holds output low outside VDD operating range. 4A High-Speed Low-Side Gate Driver Circuit diagram: Features:     Low-Cost, Gate-Driver Device Offering Superior Replacement of NPN and PNP Discrete Solutions     Pin-to-Pin Compatible With TI’s TPS2...

This High Power LEDs up to 15 Amperes Circuit Diagram employs a simple scheme that limits the current flow to the LED, you can easily modify the circuit, and can change the power just replacing the value of R2. You can use a DC source of any tensions between 9V to 15V.Para powers or other LEDs just use the approximate formula: Current (I) = 0.8/R2 where I is the current specified by the LED manufacturer. Value of I this conductor is 10A. Use R2 = 0.8/Current formula (I) to determine R2. High Power LEDs up to 15 Amperes Circuit Diagram Parts List Q1 2N3055 or similar NPN transistor R1 1W 220ohms D1, D2 1N4001 silicon diode or rectifier See R2 power for each LED R2 for 1W LED 1W 2.7ohms R2 LED to 1.5 ohms 1W 3W 5W LED R2 to 0.6 ohms or 2 x parallel 1.2-ohms/1W

The power line fluctuations and cut-offs cause damages to electrical appliances connected to the line. It is more serious in the case of domestic appliances like fridge and air conditioners. If a fridge is operated on low voltage, excessive current flows through the motor, which heats up, and get damaged. The under/over voltage protection circuit with time delay presented here is a low cost and reliable circuit for protecting such equipments from damages. Whenever the power line is switched on it gets connected to the appliance only after a delay of a fixed time. If there is hi/low fluctuations beyond sets limits the appliance get disconnected. The system tries to connect the power back after the specific time delay, the delay being counted from the time of disconnection. If the power down time (time for which the voltage is beyond limits) is less than the delay time, the power resumes after the delay: If it is equal or more, then the power resumes directly. This circuit has been desig...

High Quality Stereo Encoder with NJM2035 This stereo encoder is the perfect solution for those looking for transmitting high quality stereo sound with low cost. This stereo encoder produces crystal clear stereo sound very good and very good channel separation that can match many more expensive stereo encoders that are available in the market. It's all possible thanks to 38KHz quartz crystal that controls the 19kHz pilot tone, so you'll never go back to calibrate or adjust sirkuit.NJM2035 offer superb quality and manufactured by NJR CORPORATION (JRC), a subsidiary of New Japan Radio, a company known as the world's best manufacturers of high end professional audio semiconductors. This transmitter will work with mono FM transmitter including the TX300 and TX500 are available on our website. The entire series can easily fit on a small "x 1.5" printed circuit board that allows to adjust in a place where space is limited. While building your stereo encoder please take y...

This is a Miniature High-Rate Speed Control with Battery Eliminator Circuit (BEC) . This design is based on one published by Milan Lulic in the German magazine elektroModell. Mr. Lulic’s design is for surface mount technology (SMT) construction, whereas mine uses standard off-the-shelf components, and is therefore better suited to construction by the hobbyist. The circuit begins with a buffer, consisting of C1, R1, and Q1. This provides some isolation between the receiver and the rest of the circuit, and makes circuit operation somewhat independent of the model of receiver (although you may have to adjust R8 if you change receiver types). R2, R3, and C2 form an integrator, which produces an output voltage proportional to the pulse width of the input signal. This output voltage varies from approximately 1.15V for a 1ms input to 1.45V for a 2ms input (at 50 pulses per second). Z1A, together with R4 through R8, and C3, form a 2.5kHz triangle wave generator. R8 adjusts the upper and lower ...

This high quality and low cost speaker was designed to be used for iPod or iPhone with the use of old car Hi-Fi speaker and some computer components. Other materials used are shown in the image below and they include an amplifier, 240V-12V power supply, tweeters, crossovers, sealed lead acid battery, MDF, filler, Apple universal dock & remote, glue, nails, and white gloss paint. The front baffle board was drawn on a piece of MDF in order to use it as a template to make the rear of the box. The dimensions of the box based on the speaker do not necessarily need to be exact because the speakers were quite old as it comes from an old Renault 19. From the photo of the round bits below, the trusty circular saw was used to cut loads of 1 inch by 15 cm strips of MDF. Between the front and rear baffle, the strips were glued and nailed. The baffles were cut out using a jigsaw and the strips were kept as close to each other as possible. The first coat of filler can take 3 batches to finish an...

THE high forward voltage of l.e.d.s is a challenge for efficient battery use. In the circuit shown in Fig.1a, a 74HC14 inverter is used to “double” the voltage of a 6V rechargeable ex-mobile-phone battery and drive a string of three 5mm l.e.d.s. The oscillator around IC1a and IC1b generates a square wave at about 2·8kHz, and its output is buffered by IC1c and IC1d used in parallel to maximise current to the doubler. Booster Using a 6V supply and with 1N4148 diodes in the rectifier, which comprises D1 and D2 plus capacitors C2 to C4, results in a rectified voltage of 9·6V having a 12mA output capability for a 24mA supply current – an electrical efficiency of over 80%. Using a 6·3V battery the output voltage is 10V and the available current increases to 16mA. If Schottky diodes are used for D1 and D2, there is an increase in voltage of 100mV, resulting in a 20% increase in available current, to 19mA (6·3V supply), at similar efficiency, and a much brighter light. Using these diodes there...

Here’s a project that could be useful this summer on the beach, to stop anyone touching your things left on your beach towel while you’ve gone swimming; you might equally well use it at the office or workshop when you go back to work. In a very small space, and powered by simple primary cells or rechargeable batteries, the proposed circuit generates a low-energy, high voltage of the order of around 200 to 400 V, harmless to humans, of course, but still able to give a quite nasty ‘poke’ to anyone who touches it. Quite apart from this practical aspect, this project will also prove instructional for younger hobbyists, enabling them to discover a circuit that all the ‘oldies’ who’ve worked in radio, and having enjoyed valve technology in particular, are bound to be familiar with. As the circuit diagram shows, the project is extremely simple, as it contains only a single active element, and then it’s only a fairly ordinary transistor. As shown here, it operates as a low-frequency oscillator...

High-Performance 12V 20W Stereo Amplifier . Amplifiers which run from 12V DC generally don’t put out much power and they are usually not hifi as well. But this little stereo amplifier ticks the power and low distortion boxes. With a 14.4V supply, it will deliver 20 watts per channel into 4-ohm loads at clipping while harmonic distortion at lower power levels is typically less than 0.03%. This is an ideal project for anyone wanting a compact stereo amplifier that can run from a 12V battery. It could be just the ticket for buskers who want a small but gutsy amplifier which will run from an SLA battery or it could used anywhere that 12V DC is available – in cars, recreational vehicles, remote houses with 12V DC power or where ever. 20W Stereo Audio Amplifier Because it runs from DC, it will be an ideal beginner’s or schoolie’s project, with no 240VAC power supply to worry about. You can run it from a 12V battery or a DC plugpack. But while it may be compact and simple to build, there is n...

A simple NiCd battery charger powered by solar cells. A solar cell panel or an array of solar cells can charge a battery at more than 80 % efficiency provided the available voltage exceeds the ‘fully charged’ battery voltage by the drop across one diode, which is simply inserted between the solar cell array and the battery. Adding a step-down regulator enables a solar cell array to charge battery packs with various terminal voltages at optimum rates and with efficiencies approaching those of the regulator itself. However, the IC must then operate in an unorthodox fashion (a.k.a. ‘Elektor mode’) regulating the flow of charge current in such a way that the solar array output voltage remains near the level required for peak power transfer. Here, the MAX639 regulates its input voltage instead of its output voltage as is more customary (but less interesting). Solar-Powered High Efficiency Battery Charger Circuit Diagram The input voltage is supplied by twelve amorphous solar cells with a mi...

Subsonic and ultrasonic filters can be combined into a single circuit for more stable and orderly bandwith. This good and qualified for only two frequencies with the rotation of widely separate. Circuit schematic above shows the rotation of the scond-order or high-pass Butterworth filter in combination with secon-order low-pass filter. Part List : R1___1K R2___1K R3___12K R4___24K C1___4n4 C2___2n2 C3___470nF C4___470nF IC___IC op-amp For the capacitor , use the ceramic capacitors .

Inverter circuit on basic of really taking a series of mosquito racket, a racket in which these mosquitoes require only a low voltage. With only 3 Volts course of this series has been able to work. Circuit is raising the voltage by a transformer that can be made yourself with the need of copper wire and ferrite rods. How to making a transformer like that here , but this circuit requires a step-up transformer that are larger and require a lot of coils. This transformer is controlled by a transistor semiconductor 24D506 in this series. To output issued until 1KV or more but issued is very low amperage. This circuit can also be used in fluorescent lamps 10W maximum . When used in fluorescent lamps add another capacitor to the voltage for provoke can turn on the lights. Part List : Resistor R1____1K5 Ω R2____4K3 Ω R3____22M Ω Capacitor C1____100n C2____100n  400V C3____0.2uF 400V Diode D1___1N4007 D2___1N4007 Transistor Q1___ 24D506 Transformer L1___#100 turns L2___#100 turns...

High Quality Mosfet Power Amplifier . These amplifiers circuit can be used for virtually any application that requires high performance, low use Noise, distortion and excellent sound quality. Examples would be subwoofer amplifier should FOH stage Amplifiers, surround a canal a very powerful sound amplifier, etc. The 400W MOSFET-amplifier has four key stages of amplification. We are looking to start any Phase appropriate detail. Schematics Diagram 400W MOSFET Amplifier As the name suggests All Q ,C and ZD the Bias and buffer phases. Its main goal is to provide a stable MOSFET Gates and offset voltage and the voltage buffer amplifier stage of the High Resource capacity. What would have without the phase response and the effect Slew rate is indeed very bad. The flip side of the coin is not the extra step Introduction of an additional dominant pole in the amplifier feedback loop. Also to what the name suggests this stage converts the voltage developed in the VAS and provides all the amps r...

This inverter circuit works with a transistor and transformer and other components to increase the voltage becomes high. Input supply voltage ranging from 3V to 6V DC, later it was raised to high voltage AC. However, in this inverter circuit output current is very small, probably under 0.1A even smaller. However, its use you can apply it on a fluorescent lamp 10W maximum power only, and that too takes time to switch on fluorescent lamps. Part List R1 = 4K7 R2 = 2K2 R3 = 330K C1 = 100nF C2 = 100nF 275V C3 = 0.22uF 275V Q1 = D506 L1 = 100 times winding, with 0.8mm diameter copper wire L2 = 50 times winding, with 0.8mm diameter copper wire L3 = 5000 times winding, with 0.4mm diameter copper wire

In first part we discussed about the detail of circuit, back EMF and Mosfet protection; in the second part we will cover these: Other protection measures As already mentioned, diode D1 provides reverse polarity protection for microcontroller IC1 and the switchmode supply (IC2). Zener diode ZD1 is self-protecting in the case of reverse supply connection. However, if the supply is reversed, there will be a heavy conduction path via fast recovery diode D3 and the internal substrate diodes in the four power MOSFETs. If you are lucky, the 50A fuse will blow before the MOSFETs are damaged, but there is no  guarantee of this. SO dOn’T rEVErSE THE bATTErY cOnnEcTIOnS! In a similar vein, if the outputs are shorted while power is applied, high current will flow  through the MOSFETs. Again, if you are lucky, the 50A fuse will blow before the MOSFETs go up in smoke. In reality, the 50A fuse is there to stop a fire! SO dOn’T SHOrT THE OUTPUTS TO THE MOTOr. If the motor is under heavy load ...