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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...

Priject of Receiver and Transmitte r Low Cost Data Circuit Diagram. Here are two simple circuits that can be used for transmission and reception of data via RF to UHF frequency (433MHZ). Two circuits are super simple, no special components and has a good performance, but short range. It is set to the frequency of 433MHZ, but nothing prevents that with some modifications it works on other frequencies.  Receiver and Transmitter Low Cost Data Circuit Diagram 1 The range is small, ideal for data transmissions within an environment like office, garage, laboratory, workshop or room. This system of data communications short-range 434MHz can be used in projects of alarms, electronic gates, trigger devices from a distance, Arduino, etc. .. X1 is working on a crystal harmonic (433.92Mhz) and L1 receiver comprises 1.5 turns of wire must be tested diameter and thickness to reach the perfect reception of the transmitter.  Receiver and Transmitter Low Cost Data Circuit Diagram 2 You can mou...

This is a Simple But  low-power inverter uses only 9 parts and turns 10 to 16 Vdc into 60-Hz, 115-V square-wave power to operate ac equipment up to 25 W. The first section of the 556 timer chip is wired 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. Low-Power Inverter Circuit Diagram:  That output is available at pin 9. Resistors R3 and R4 keep output transistors 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 120 V/18 VCT unit that is connected backwards, so that it steps the voltage up rather than down. Oscillator circuit U1, R1, R2, and C1 operates from about 4 to 16 V with a very ~stable output.

If you want to check the behaviour of an electronic circuit at low voltages, an adjustable power supply as shown here may be helpful. Powered from a 3 to 16 volts source (DC for sure), it will provide a stable output voltage in the 0 to 1.5 V range. Adjustable Low-voltage Power Supply Circuit Diagram Multiturn trimpot P1 allows the output volt-age to be adjusted with good precision. The BC337-400 output transistor raises the out-put current to about 200 mA bearing in mind that the minimum supply voltage is 3.5 V. The transistor’s dissipation should be taken into account, and a more power ful t ype used if necessary. T1 may be omitted and R2 replaced with a wire link if you are happy with 3 mA at 3 volts out, 10 mA at 6 V or 20-30 mA at 10-16 V. These values represent the maximum output current of the TLC271 op amp. Without T1, the minimum supply voltage is 3.0 V. Author:Vladimir Mitrovic - Copyright: Elektor

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 ...

LDO regulator means low dropout regulator. An LDO voltage regulator is just a DC linear voltage regulator which can be operated with a very small input-output voltage differential. This input output voltage differential is called dropout voltage. In simple words dropout voltage is the voltage dropped by the regulator circuitry alone for its working. For example, an LM2941 LDO voltage regulator has a dropout voltage of only around 0.5V, which means that in order to get 5 volts at the output you need to input only 5.5 volts where an ordinary 7805 linear voltage regulator has a dropout voltage of around 2V. This means that, in order to get 5V at the output of 7805 you need to input at least 7V. LDO regulator working. Schematic of a LDO regulator The image shown above is the schematic of a typical LDO voltage regulator. The working principle of LDO regulator is just like that of an ordinary linear voltage regulator. The essential components of an LDO voltage regulator are a reference volta...

A novel use of solar cells makes positioning your car in the garage rather easier than old tyres, a mirror, or a chalk mark.The six solar cells in figure 1 serve as power supply and as proximity sensor. They are commercially available at relative low cost. The voltage developed across potentiometer Pi is mainly dependent on the intensity of the light falling onto the cells. The circuit is only actuated when the main beam of one of the car's headlights shines direct onto the cells from a distance of about 200 mm (8 inches). The distance can be varied somewhat with P, Low Cost Garage Stop Light Circuit Diagram : Under those conditions, the voltage developed across C1 is about 3 V, which is sufficient to trigger relaxation oscillator Ni. The BC547B is then switched on via buffer N2 so that D3 begins to lfash. Diodes Di and D2 provide an additional in-crease in the threshold of the circuit. The total voltage drop of 1.2 V across them ensures that the potential at pin I of the 4093 is ...

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...

Here is very simple low-cost electronic circuit project of low state car battery indicator circuit. This electronic circuit diagram designed using few common electronic parts. This low state battery electronic project can be used to monitor car battery voltage. Low-Cost Low State Car Battery Indicator Circuit Diagram: The warning light LED indicates when battery indicates battery voltage falls bellow level set by 10k potentiometer, if the battery is defective or needs charging if cranking drops battery voltage bellow preset safe limit. This circuit project is very simple so it not requires some other explanation.

All miniature electronic devices operate off batteries. Some of them need higher than the standard battery voltages to operate efficiently. If the battery of that specific voltage is unavailable, we are forced to connect additional cells in series to step up the DC voltage. Thus, the true meaning of miniaturisation is lost. A simple way to overcome this problem is to employ a voltage doubler, if the device under consideration can operate at a small current. Here we present a low-power voltage doubler circuit that can be readily used with devices that demand higher voltage than that of a standard battery but low operating current to work with. The circuit is quite simple as it uses only a few components. Yet, the output efficiency is 75 to 85 percent along its operating voltage range. The available battery voltage is almost doubled at the output of the circuit. Here IC1 is wired as an astable multivibrator to generate rectangular pulses at around 10 kHz. This frequency and duty cycle of...

This is a heavy duty but low-cost Electronic Circuit . The operation amplifier A1 directly drives the VN64GA with the error signal to control the output voltage. Peak rectifier Dl, CI supplies error amplifier A1 and the reference zener. This extra drive voltage must exceed its source voltage by several volts for the VN64GA to pass full load current. Heavy Duty But Low-Cost Battery charger Circuit Diagram: The output voltage is pulsating dc which is quite satisfactory for battery charging. To convert the system to a regulated dc supply, capacitor C2 is increased and another electrolytic capacitor is added across the load. The response time is very fast, being determined by the op-amp. The 2N4400 current limiter circuit prevents the output current from exceeding 4.5 A. However, maintaining a shorted condition for more than a second will cause the VN64GA to exceed its temperature ratings. A generous heat sink, on the order of 1°C/W, must be used.

This Circuit use IC BA518 or you can use the IC BA547 , this is low mono power amplifier. Maximum power output 5W . But this is also low voltage amplifier with minimum voltage require 2 Volt. And maximum voltage 12 Volt .Impedance 8 Ohm , support small speakers. Circuit schematic below : Click image to view large Troubleshooting if circuit not working  : Check components are can be use or not , also check the use avometer or other measuring instrument.  Check the voltage on each component.   If there is a voltage that has not been entered on the components, then see if there is a broken line or short-circuit PCB , thereb inhibiting the incoming flow. Then check  whether the input and output cables are still good or not.

This Circuit use IC BA518 or you can use the IC BA547 , this is low mono power amplifier. Maximum power output 5W . But this is also low voltage amplifier with minimum voltage require 2 Volt. And maximum voltage 12 Volt .Impedance 8 Ohm , support small speakers. Circuit schematic below : Click image to view large Troubleshooting if circuit not working  : Check components are can be use or not , also check the use avometer or other measuring instrument.  Check the voltage on each component.   If there is a voltage that has not been entered on the components, then see if there is a broken line or short-circuit PCB , thereb inhibiting the incoming flow. Then check  whether the input and output cables are still good or not.

This amplifier circuit is very cheap, because not a lot of components that are required, and the voltage or amperage required is also not too large, so the transformer or power supply is also quite cheap. IC which can be used in power amplifier circuit is the KA2201, LM820M, TBA820M, U820. This amplifier output of 2 W and 4 ohm impedance, which can be applied to the speaker with 4W power, on such small speakers in front of a PC. For the required minimum input voltage of 3 volts and a maximum of 16 volts, for the recommended voltage of 12 volts. Parts Resistor R1 = 100K R2 = 120R R3 = 100R R4 = 10R Capacitor C1 = 0.1uF C2 = 100uF C3 = 47uF C4 = 100uF C5 = 470uF C6 = 220pF C7 = 100nF IC U1 = KA2201 , LM820M, TBA820M, U820

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...

Description. Here is the circuit diagram of a simple and low cost AM radio. The working of this radio circuit is straight forward. Inductor L1 and capacitor C1 forms the necessary tank circuit. Diode D1 performs the job of de-modulation. Transistor T1 is wired as a preamplifier whose output is further amplified by the IC LM386 to drive the head phone Z1. The 10K POT R3 can be used as a volume controller. Circuit diagram. Notes. The circuit can be powered from a 9V PP3 battery. Use a 100cm long metal wire as antenna. Experiment with the value of L1 for catching other bands. The circuit can be assembled on a Vero board.

Low-Cost Electronic Project of RF Synthesizer Uses Generic ICs . You can design a hardware-based frequency synthesizer with one inexepensive IC and a few passive components. Such synthesizer chips are not always available, however, because they are typically single-sourced and are not in stock with parts distributors. The need for a working circuit in a short time and using common parts prompted the creation of the circuit in this Design Idea. The synthesizer covers the US commercial AM (amplitude-modulation) broadcast band. It tunes in 10-kHz steps from 500 to 1800 kHz, but you can scale the frequencies for other applications. The PLL (phase-locked loop) time base is a 100-kHz, tuning-fork-cut crystal of the same size as those in wrist watches. Using a more common crystal requires some extra parts to scale the frequency. Note that if you attempt to use one of these tiny crystals with a CMOS gate oscillator circuit, however, the circuit will either fail to start or exhibit visible jit...

This electronic circuit is a simple VHF FM transmitter circuit. The circuit can easily make portable use for a small 9 volt battery. Transmitter range from 60 to 100 meters range.  The construction of the circuit is very simple. Electrically adjustable frequency between 88 and 108MHz. Portable and low power consumption. You can use any FM receiver. 9 Volt works. Portable and Low Power VHF FM Transmitter Circuit Diagram Parts list: R1 = 10K R2 = 15K R3 = 3.3K R4 = 470 ohm R5 = 100K R6 = 4.7K VR 1 = 10K Pot meters VALUE C1 = 0.1uF----- 104 C2 = 0.001uF---- 102 C3 = 0.0015uF---- 152 C4 = 10pF ----- 10 C5 = 3pfF ----- 3 C6 = 2.5pF----- 2.5 C7 = 10pF ----- 10 C8 = 0.01uF---- 103 C9 = 0.022uF----- 223 C10 = 1pF ----- 1 C11 = 0.001uF---- 102

As electrolytic capacitors age, their internal resistance, also known as "equivalent series resistance" (ESR), gradually increases. This can eventually lead to equipment failure. Using this design, you can measure the ESR of suspect capacitors as well as other small resistances. Basically, the circuit generates a low-voltage 100kHz test signal, which is applied to the capacitor via a pair of probes. An op amp then amplifies the voltage dropped across the capacitor’s series resistance and this can be displayed on a standard multimeter. In more detail, inverter IC1d is configured as a 200kHz oscillator. Its output drives a 4027 J-K flipflop, which divides the oscillator signal in half to ensure an equal mark/space ratio. Two elements of a 4066 quad bilateral switch (IC3c & IC3d) are alternately switched on by the complementary outputs of the J-K flipflop. One switch input (pin 11) is connected to +5V, whereas the other (pin 8) is connected to -5V. The outputs (pins 9 & ...

Low current relay This low current relay circuit is designed to be used in battery operated electronic devices. Its operating current is in micro amperes (µA). This is done by using a bistable relay and adding some components to force the relay to behave like a monostable relay. A bistable relay stays at its last state when the power is turned off but consume at least 50mA trigger current. A monostable relay switches back to its original state when the power is turned off. How does the low current relay works? When the power is turned ON, the C1 charges via D1 and the relay coil and this current activates the relay. D1 ensures that the base of T1 is always more positive than its emitter and because of this T1 and T2 are always blocked. Once the power is turned OFF, the emitter of T1 is coupled to the charge voltage at the positive pole of C1. Its base and the relay coil on the other hand are coupled to the negative pole of C1 and now T1 and T2 conduct, C1 can discharge through T2 and r...