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Simple and cheap, the circuit built based on well-known IC regulator LM317 with current booster of power transistor 2N3782. Don’t forget to add heatsink especially for power transistor 2N3782.

This circuit will supply up to about 20ma at 12 volts. It uses capacitive reactance instead of resistance; and it doesn't generate very much heat.The circuit draws about 30ma AC. Always use a fuse and/or a fusible resistor to be on the safe side. The values given are only a guide. There should be more than enough power available for timers, light operated switches, temperature controllers etc, provided that you use an optical isolator as your circuit's output device. (E.g. MOC 3010/3020) If a relay is unavoidable, use one with a mains voltage coil and switch the coil using the optical isolator.C1 should be of the 'suppressor type'; made to be connected directly across the incoming Mains Supply. They are generally covered with the logos of several different Safety Standards Authorities. If you need more current, use a larger value capacitor; or put two in parallel; but be careful of what you are doing to the Watts. The low voltage 'AC' is supplied by ZD1 and ZD2....

Because of energy crisis Load shedding may be a common problem in several countries.. Sudden power fluctuations, surge and high voltage may spoil sophisticated household appliances like TV, VCR, VCP and music system. This circuit provides protection against these problems and automatically changes the power supply from Generator output to mains supply and also switches off the generator. Circuit descriptions This circuit is self explanatory. When lines supply voltage crosses the preset level, Zener diode ZD4 break down and thus transistor T2 conducts, T3 does not conduct, causing the relay to de-energise. Voltage surge at the time of power resumption is protected by the delay circuit around transistor T1. All the portable petrol and kerosene generators have a connection from CDI. To stop the engine of the generator-set, this connection is to be grounded momentarily (through the switch). This lead is to be connected with the ground through the N/C point of the relay. Auto Changeover ...

This low-cost, multipurpose power supply fulfils the requirements of almost all laboratory experiments. Nonetheless, it can be easily fabricated by hobbyists. A single transformer is used to build this triple power supply. Regulator IC LM317 generates variable power supply of 1.25 to 20V, 1A. The dual ±12V, 1A power supply is generated  by regulators 7812 and 7912. Similarly, dual ±5V, 1A power supply is generated by regulators 7805 and 7905. ‘On’/‘off’ switches (S2 through S4) select the required power supply. Variable power supply is used to study the characteristics of devices. Fixed +5V power supply is used  for all digital, microprocessor and microcontroller experiments. Dual ±12V power supply is used for op-amp-based analogue circuit experiments. Circuit diagram : Fig. 1: Triple power supply Circuit Daigram   Fig. 2: Pin configurations of regulators Fig. 1 shows the circuit of the triple power supply, while Fig. 2 shows the pin configuration of the regulators used in th...

Basic Of Switch Mode Power Supply In recent years, the use of switch mode power supply (SMPS) has become more comon as more applications demand for greater power eficiency. It makes use of semiconductor (mostly MOSFET) fast switches to switch DC input that has been rectified at high frequency. The advantages of high frequency switching are that it reduces the size of inductor, capacitors & transformer used. Other advantages of switching power supply over linear power supply are : 1) High Efficiency (up to 90% and above for nice design). 2) Output can be higher than input. 3) Able to operate over a variety of input power supply. 4) Able to have over output. The setback of using SMPS compared to linear power supply is that it generates electrical noise which contributes to electromagnetic compatibility design issues & more part count. Buck Converter SMPS The SMPS circuit below from Power Integration makes use of LNK304 as its high frequency switch. Take note that this circuit is...

There will be instances where the currents from each supply will be unequal. Where this is the case, the resistor divider is not sufficient, and the +ve and -ve voltages will be unequal. By using a cheap opamp (such as a uA741), a DC imbalance between supplies of up to about 15mA will not cause a problem. However, we can do better with a dual opamp (which will cost the same or less anyway), and increase the capability for up to about 30mA of difference between the two supplies. Dual Opamp Buffered Power Supply  Circuit diagram: Dual Opamp Buffered Power Supply Circuit Diagram Author: http://sound.westhost.com/project43

Occasionally you come across some unusual  situations when setting up measurement  systems. The author once had to set up a system to register the vibrations and strain supposed to be  present in a contactor that operated at a voltage of 25 kVAC. One of the biggest problems with this project turned out to be the power supply for  the measurement system. Since it required  a power of about 30 W it wasn’t possible to  use batteries since the system had to operate  for many hours at a time. A logical solution  would seem to be to use an isolating trans-former, but still.25 kVAC means a peak volt-age approaching 40 kV, and on top of that  you would have to include a safety margin. In  addition, everything that is connected to high  voltage lines should also be able to withstand  lighting strikes! Circuit diagram : Power Supply with High Voltage Isolation Circuit Diagram Consequently the isolation should be able to  cope with a test voltage of 150 kV, which is a  lot to ask of the is...

3V DC to 5V DC REGULATED POWER SUPPLY ELECTRONIC DIAGRAM A 5V DC regulated output from 2 cells 3V DC batteries. The output current of the circuit is limited to 50mA. However, it still able to supply many microcontroller circuits. 3009 and 560R Resistor provide the 5V DC output, make up a voltage divider network.

This is a Variable 5 to 20V DC Supply Circuit Diagram . If you are looking for a low drop voltage regulator that can provide a power supply of 1A with an output voltage of between 5V and 20V DC, National Semiconductor LM2941 Low Dropout Adjustable Regulator is that you can pick to make use of. It's a typical dropout voltage of 0.5V which means that the input supply need only must be 0.5V DC over the desired output voltage.  Variable 5 to 20V DC Supply Circuit Diagram   Its other features include internal short circuit current limit and reverse battery protection. As shown in the schematic below, the regulator has five pins which consists of the ON/OFF control, Input Voltage, Output Voltage, Ground & Adjustable pins. ON/OFF is used for the purpose of switching on & off of the regulator. The capacitors C1 & E1 are to be placed as close as feasible to the regulator.  The output of the circuit can be varied by varying the worth of potentiometer VR1 from 5V DC to 2...

This circuit supplying current maximum10A with an adjustable output voltage from 0-25 VDC. Adjustable Switching Regulator L4970 Series is built with the main component as a Switching Regulator IC L4970. Switching Regulator L4970 series include not complicated to make his own, which need to be considered is the IC L4970 require sufficient cooling to operate in an optimal and durable. Adjustable Switching Regulator L4970 series are complete can be seen in thethe following figure . Adjustable switching power supply schematics To set the output voltage range Adjustable Switching Regulator L4970 can be in control by adjusting the potentiometer 18KOhm tus.

This is a Variable Power Supply Circuit Diagram Use LM317 . A truly timeless circuit. LM317 is a versatile and highly efficient 1.2-37V voltage regulator that can provide up to 1.5A of current with a large heat sink. It's ideal for just about any application. This was my first workbench power supply and I still use it.  LM317 VARIABLE POWER SUPPLY Circuit Diagram Since LM317 is protected against short-circuit, no fuse is necessary. Thanks to automatic thermal shutdown, it will turn off if heating excessively. All in all, a very powerful (and affordable!) package, indeed. Although LM317 is capable of delivering up to 37V, the circuit pictured here is limited to 25V for the sake of safety and simplicity. Any higher output voltage would require additional components and a larger heat sink. Make sure that the input voltage is at least a couple of Volts higher than the desired output. It's ok to use a trimmer if you're building a fixed-voltage supply. Possible uses: Variable w...

This is a Simple 0.5V Negative Supply Circuit Diagram . This simple circuit consists of two LEDs and a photo diode. It generates a negative voltage with a current level of a couple milliamps. It is ideal for supplying a negative rail to low power “rail to rail” op amp circuits, which need to have a true zero volts output. Note: This circuits is not particularly efficient.   Simple 0.5V Negative Supply Circuit Diagram

Do you need high current power supply without heavy and expensive transformer? Then, this circuit would be great choice for you. This 13.8 Volt 20 A regulated transformer less power supply. 20A transformer is very-very expensive, large in size and very heavy in weight. This power supply capable in delivers around 20Amps at 13.8V. For lower currents, a separate current limiting output, capable of 15ma up to a total of 20A has been added. Let us see what we have got here. The power transformer should be capable to deliver at least 25A at 17.5 to 20V. The lower the voltage, the lower power dissipation. The rectified current will be ironed by the C1, whose capacity should not be less than 40.000uF, (a golden rule of around 2000uF/A), but we recommend up to 50.000uF. This capacity can be built up by several smaller capacitors in parallel. The base of this design is a simple 12V regulator IC 7812.

ABSTRACT In our day to day life we came across various power problems that include black out, voltage sag, frequency variation, surge, harmonics etc. Among this entire problem black out is the most critical situation for some critical load like ICU, space shuttle lunch, major software installation etc. In these cases the power failure even for a few micro second can cause major problems. To overcome from this type problem we are using uninterruptible power supply (UPS). Although there are various type of UPS available, but among this static UPS is more preferable due to its advantages over other types. Static UPS not only provides stand by power to the load but also provides a qualitative power which is a pure sine wave. The use of this device not only limited to industrial application but it spreads starting from computer to space research center. There are different type of UPS available and we can use them depending upon our load type and how sensitive it is. 

This is a simple but powerful power supply , which can deliver up. 5 AThe circuit works with the aid of a normal voltage regulator of the type 78xx and a buffer transistor. When the output current exceeds 200 mA, then T1 takes over, allowing the maximum output current is 5 amperes. The 78 series regulator is available from 5 to 24 volts. In the place of the xx is the voltage, so 7812 for a 12 volt regulator.Take the AC in 5% higher than the desired output voltage. In that case it is below the wrinkle.T1 is a MJ (E) 2955. It must be properly cooled at higher output currents.  5 A stabilized Power Supply Circuit Diagram Parts List      R1 = 3.3 Ω 5 Watt      C1 = V 4700μF/63      C2 = V 10μF/35      C3 = 100nF      D1 = 35A      T1 = MJ2955 (TO220), MJE2955 (TO3), TIP2955 (TO247)      IC1 = 78xx      F1 = 5A

Build a 1.2-36V 5A Adjustable Power Supply circuit diagram with LM317 . This circuit is a simple power supply circuit. 1.2 - 36V adjustable bench power supply with 5A of output current. Max input voltage is 37V and output is adjustable via potentiometer between 1.2 up to 36 volts. TIP147 PNP darlington transistor boosts the current of LM317 from 100mA to 5A. LM317 is the most useful and inexpensive adjustable regulator and for this circuit you can also use LM317 L that can give 100mA, that's enough for transistor bias.   1.2-36V 5A Adjustable Power Supply Circuit Diagram  D1 and D2 are protection diodes because when you turn the circuit off the output capacitors are discharging and can damage the transistor or regulator. 100nf capacitors are in parallel with electrolytic capacitors to remove high frequency noise because large value electrolytic have large ESR and ESL and can't remove high frequency noise.

Switching Power Supply in this article are able to supply power 90 Watt. Switching Power Supply series is built directly from an AC network system using special IC MC33374 switching power supply in the form of High Voltage Power Switching Regulator and with external components to the other. IC MC33374 IC is a switching power supply designed to operate with an AC voltage source and works as a power switching converter with flyback technique. Switching Power Supply Series has a 15 volt DC output with current up to 6 Ampere. 90 Watt Switching Power Supply Schematic Series 90 Watt Switching Power Supply works by menyearahkan AC source is then used to activate the converter MC33374 system. The output of transformer switching converter MC33374 searahkan again later on as a DC voltage supply to be used for electronic devices.

Power Supply in this article use a regulator that is composed of 2 pieces of NPN transistor. A transistor acts as a power regulator and a transistor again serves as a controller output voltage. Power Supply has an adjustable output with a range of 6-12 VDC. The part that serves as a power regulator is Q1 TIP31. Then the controller output voltage is a voltage divider composed of R3, R4, VR1 and R2 provide bias to the base of Q2 to Q1 mengentrol power regulator. In a series of power supply is mounted 5.1 V zener diode which serves to make the minimum limit the output voltage with Q2. Adjustable Power Supply with transistor circuit Power Supply With transistor circuit is quite simple and can be made with the PCB holes, so for those who want to try to directly mempraktikannya. May the power supply circuit can be useful for readers, especially for friends who need a power supply circuit with the regulator transistor.

The switching regulator power supply used LM2575-5.0 on this schematic. You can make the stable voltage by using the 3 terminal regulator like LM317. However, because the output electric current and the inputted electric current are the same approximately, the difference between the input electric power (The input voltage x The input electric current) and the output power (The output voltage x The output current) is consumed as the heat with the regulator. Because it is, the efficiency isn�t good. Data sheet for LM2575 SIMPLE SWITCHER 1A Step-Down Voltage Regulator http://www.national.com/pf/LM/LM2575.htm

The schematic above can be used for supply on color TV for all type TV circuit. But we need to know how much voltage needed by the circuit of color Television. To set the output voltage, the setting on VR1 1K ohm. Required input voltage 300V DC which is already on TV circuit, so we just take a 300V dc voltage existing on the TV circuit, and for a circuit supply voltage on our TV cut the line PCB and connected with this  universal switching power supply.For the transformer we can use the TV regulator transformer. Part List : R1 = 33R 5W R2 = 330R 1W R3 = 2K2 R4 = 47K R5 = 2K7 R6 = 22K R7 = 390K R8 = 47R 1W C1 = 100uF 25V C2 = 1n2 2KV C3 = 18n C4 = 18n D1 = 1N4148 D2 = 1N4148 D3 = ZD 12V D4 = 1N4007 D5 = 1N4007 VR1 = 1K ZD1 = Zener 6V T1    = TV regulator transformer Q1   = K2847 Q2   = C2328A PCB line Finishes circuit