What is Power supply: Definition and 301 Discussions

A power supply is an electrical device that supplies electric power to an electrical load. The primary function of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load. As a result, power supplies are sometimes referred to as electric power converters. Some power supplies are separate standalone pieces of equipment, while others are built into the load appliances that they power. Examples of the latter include power supplies found in desktop computers and consumer electronics devices. Other functions that power supplies may perform include limiting the current drawn by the load to safe levels, shutting off the current in the event of an electrical fault, power conditioning to prevent electronic noise or voltage surges on the input from reaching the load, power-factor correction, and storing energy so it can continue to power the load in the event of a temporary interruption in the source power (uninterruptible power supply).
All power supplies have a power input connection, which receives energy in the form of electric current from a source, and one or more power output connections that deliver current to the load. The source power may come from the electric power grid, such as an electrical outlet, energy storage devices such as batteries or fuel cells, generators or alternators, solar power converters, or another power supply. The input and output are usually hardwired circuit connections, though some power supplies employ wireless energy transfer to power their loads without wired connections. Some power supplies have other types of inputs and outputs as well, for functions such as external monitoring and control.

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  1. A

    Need a negative voltage from a 0-60V power supply

    I will have to power the following circuit: http://www.tekscan.com/images/flexi-circuit-new.jpg I assume I can just hook the (-) terminal to the -9V input, the (+) terminal to the +9V input, set the power supply to 9V, and then toss a resistor between the -9V and the -5V? Would that...
  2. R

    If I install stronger PC power supply in terms of watts

    ...than my current unit,is there danger that some component in my PC will be destroyed?
  3. G

    Transformerless AC to DC power supply

    Help! I was trying to build an AC to DC power supply circuit without using transformers. I followed the circuit diagrams given online, which has the 240VAC connected to a resistor at the live and a full wave rectifier whose output was connected to a capacitor and a zener diode. The figure is...
  4. B

    Building a lab power supply from a computer

    I found this link and thought it may be of some use to build a power supply. I know that these power supplies can pack around 500W on the right power supplies. Is there anything I should know and be careful of when making this and when playing with smaller electronics...
  5. C

    How do I safely build a variable DC power supply for my electronics projects?

    I'm taking an intro electronics class and I'm really enjoying it. I want to be able to work with electronics in my garage, I have a proto-board and but I would like to build a power supply that can go from 1vdc to 15vdc, this is what my class has. I've looked on the net for instructions, but...
  6. R

    24V to 5V Power Supply Solution for AVR & Other Stuff

    I have a 24 V lead acid battery that I am going to use for a power supply. I need to get 5 volts so that I can power an AVR some other stuff. I was originally intending to use a 7805 to get 5 volts, but I am concerned that this may be too much power dissipated. I think I need about 200-300 mA...
  7. F

    What is the purpose of a dual adjustable DC power supply and how does it work?

    hello , DC (I guess AC too) power supplies have 3 terminals: plus, ground, minus. If I set the voltage to 30 Volts, and plug one cable in the + terminal and the other in the - terminal, is the voltage across the wires 30 volts or 60 volts? When do we use the ground or the negative? I...
  8. M

    Power Supply Failure? PC Won't Power On

    Hello, My PC stopped working a little while ago, and I think the power supply went out, but I'm not sure. It will not power on at all, but the light on my motherboard is still lighting up. Is this most likely a problem wih the power supply?
  9. 4

    Troubleshooting Computer Power Supply Issues

    my power supply for the computer has just burnt resently for the second time in less than twom weeks i obviously have to buy anothr one but am a bit hesitant cause i can't figure out y they keep burning nd the fault is not with my plugs please help wer u can...!:yuck::biggrin:
  10. P

    RLC Circuit - AC Power Supply

    Homework Statement The figure below shows the time variation of the current through an electrical heater when it is plugged into a 240 V, 50 Hz outlet. 1) What is the peak voltage? 2) What is the rms value of the current drawn by the heater? 3) What is the resistance of the heater...
  11. E

    DC power supply with DE-9 connection

    I have a photodiode/amplifier module, which has a D-sub connection for the power supply. The manufacturer sells a power supply, but it is out of my budget range, and the lab only has standard laboratory PSU's (+V,-V, gnd). Is there any connections so that I can use this module with my power...
  12. Dual output dc power supply questions

    Hi, actually someone already posted the same questions but I thought it would be weird to continue from that post as I have a lot of questions of my own. The assignment requires me to draw a schematic diagram of a dual output dc power supply, identify the sub sections that make up the power...
  13. G

    Can You Safely Use a Center Tapped Transformer for a Dual Polarity Power Supply?

    I'm designing a set of voltage and current sensors for use with a solar system. I have developed all of the circuits, but it requires both positive and negative voltage supplies. I want to use the classic design using a center tapped transformer with two regulators. But I'm not sure what will...
  14. R

    Dual polarity power supply circuit question

    I'm having trouble with the power supply portion of an opamp circuit I'm working on. The supply is +/- 5 Volt using 7805/7905's. Half wave rectifiers provide the unregulated input with 1000uF input caps and 100uF output caps. AC is supplied by a 13VAC 'wall wart' with no center ground tap...
  15. U

    Connected the capacitor to a DC power supply

    A few days ago, I was in the lab doing some experiments with capacitors and something weird happened... I connected the capacitor to a DC power supply and after a few seconds the capacitor has popped. The voltage applied to it was within its working voltage, so that was not the cause. My...
  16. J

    Creating a Portable 6V 1A Battery Power Supply for a Modem: Where to Start?

    I'm trying create a battery power supply to create a portable modem. The modem runs off an AC wall adapter, and on it, its written to have 6V 1A output. My power supply needs to have the same output characteristics, but be battery powered. Can someone please point me in the right direction? Thanks
  17. P

    Need power supply for 200 5 volt leds

    I'm thinking of making a 200 led grow light using red and blue leds(5v). I have little knowlage on electronics. I was wonder if a computer power supply could be used and what other componets would be needed. I'm trying to get this built by late February to start growing my veggies (new project...
  18. D

    What does the efficiency bell curve of a good power supply look like?

    What does the efficiency bell curve of a good power supply look like? Should the curve peak out at typical load?
  19. D

    Finding out internal resistance of a lemon when used as a power supply

    Hi There, Right I recently did an experiment in Physics to find out the internal resistance of a lemon when used as a power supply. We connected the lemon to a voltmeter, ammeter and variable resistor, changed the resistance on the variable resistance and measured the voltage and current...
  20. J

    AC to DC Power Supply Ground Connection

    Hello, I opened up an AC to DC power supply today to see where they connected the Earth ground wire and I found that it's connected to the negative side (labeled V-) of the DC output. V- is also connected to one side of the transformer's output. Why would they connect the Earth ground wire in...
  21. K

    Do I Need a Capacitor to Smooth DC in My Power Supply?

    Hi to everyone, I would like to build a simple power supply, converting 230vac to 230vdc. I have already purchased a full bridge rectifier rated @ 400v 35amps. Q1) I would like to draw 5-10amps dc Q2) Do I need to smooth the dc with a capacitor. Q3) If So, what size and type of...
  22. J

    Which Power Supply Design Is Best for Low Noise Applications?

    Hello, I'm trying to decide how to design the power scheme that will supply the various voltages within my project. The two big requirements are that there is a single main supply, regulated 5V @ 1A (typ. load .5A), and extremely low noise regulated 12V @ 1A (typ. load .4A). The low noise 12V...
  23. D

    15 Kv linear power supply Help?

    Homework Statement Hi friends, We are working on a project for devloping a HIGH VOLTAGE POWER SUPPLY Around 15 Kv for CO2 Laser. Atpresent we have the power supply using 1N4007 that have a Vrrm (Peak inverse voltage of 1000 V).We have uses 80 Diode in series as a diode bank. To...
  24. D

    Changing AC Frequency: Gareth's Power Supply Query

    Hi, I'm technically a biologist so talk slowly! Can anyone tell me, or point me in the right direction of a resource, that explains how you can change the frequency of an input AC source? e.g. in a "lab-pack" power supply. Thanks very much, Gareth
  25. E

    How Does a Dual Output DC Power Supply Work?

    Hi, I'm in dire need for help in my assignment. I have been asked , a), to research on a dual output DC power supply (Output = +15v and -15v) of not more than 15 components and to identify the different sub-sections that make up the power supply on the schematics. And, b), give an explanation...
  26. C

    Attaching a LED to the comp power supply

    I bought three LEDs, three 1k ohm resistors, and some wire. When I bought the LEDs, I made the person show me that they worked. He connected the negative end of the LED to the yellow wire, and the positive part to the resistor, which he then connected to the black wire. The LED lit up. As far...
  27. G

    Can I connect two 12v rails on a PC power supply?

    I just bought a 320w TEC to cool my processor. But the problem is, I can't afford a power supply that can provide enough amps through a single 12v rail. If I buy a power supply that has dual 12v rails, can I wire them together in order to provide enough amps to the TEC? I won't have anything...
  28. A

    Power supply for solenoid valve

    what's the difference between AC and DC power source for solenoid valve?and what is mainly the power consumed for? for mature products available, what should be taken into consideration for power design? thanks
  29. S

    Power supply and creative inspire 2.1 2500 question

    urgent power supply and creative inspire 2.1 2500 question hello every one this is urgent... i am trying to fit computer speakers in a car the computer speakers need 12V@ 2.9 A DC the car battery is of 12V DC but of a lot more amperes the problem is i want to make a filtered power...
  30. C

    Internal voltage and resistance of a power supply

    Homework Statement Ok, you'll have to bare with me on this problem, this topic is not covered as part of my second level education. I think that ye do this in the US though. You are given a circuit containing a non-ideal power supply, an NTC resistor, an ammeter, a voltmeter, and a switch...
  31. M

    Make a SMPS Power Supply - Get Help Now!

    i need help in making of smps power supply...i have the circuit of smps circuit...how can i practically implement this circuit...please help...
  32. Cyrus

    Can I Buy/Build a 500V 4A Power Supply?

    Is it unreasonable to buy or build a power supply circuit that is rated at 500V and 4Amps? Thanks. I know 500V is possible, but not at that high an amperage. Anything in and around $5k would be fine.
  33. 2

    Need a DC power supply - amplifier?

    I need a DC power supply for a project I'm working on. I have a Leach amplifier with a monster power supply and heat sinks able to handle it clipping at ~500W/channel. It's just sitting on my floor. I also have a 2 16bit 1MHz DACs and 2 16bit 200KHz ADCs attached to a National Instruments...
  34. M

    Smallest, Cheapest 110VAC -> 20VDC, 10AMP Power Supply

    All, Well, I have this idea for a patent ... but ... it requires a power supply ... and I can't find one that meets my needs. I need to come up with the smallest, cheapest 110VAC -> 20VDC, 10AMP (or close to that) power converter (about 190 - 200 Watts), constant voltage. Small means...
  35. S

    Hi Everyone AC-DC Power Supply ?

    Hello, I'm new here and I apologize for my first post being a design question. I'm a 20 year old junior Electrical Engineering student from the University of Akron. I need some help with a design that I can't get working for the life of me! If you know pSpice Schematics, or OrCAD Capture...
  36. J

    How do you build a 5.0V regulated power supply?

    i am stuck. i have no idea how to start on this project. I have to build a power supply that produces 5.0V regulated. i can't use regulators so i have to build it but i have no idea how to get started. i have an ac course to start with. i would appreciate any ideas, insights or designs you might...
  37. S

    Modified a computer power supply into a lab power supply

    I recently modified a computer power supply into a lab power supply. I would like to check the amperes bieng output, but where can I get an ammeter? Or can i make one and how much does one cost. Heres a link to a pic of my PSU http://i106.photobucket.com/albums/m261/Squall_11/PSU002.jpg
  38. N

    Connect power supply to new video card?

    I recently bought an nVidia 7600gt video card and I can't figure out if I am supposed to hook it up to the power supply or not. I have a friend that has the 6800xt and it does hook up to the PS. But nowhere in the manual does it say that this card should hook up to the PS. Here is the card...
  39. E

    Universal laptop power supply?

    "Universal" laptop power supply? My father had an extra laptop lying around that despite being old and having had it's monitor separate from it's chassis was in perfect working order. Or such was the case several months ago - I dusted it off today and it refused to start. I got out my...
  40. T

    No Display After Replacing 750W Power Supply: Troubleshooting Ideas

    I just bought a new 750W powersupply off of newegg and put it in my computer and tried to fire it up. The fans on the back of my computer spun for a fraction of a second then everything turned off. My monitor kept going from green light to orange light for some reason (even when I turned off the...
  41. B

    Power supply voltage homework

    Need a little help here...getting started. I don't really understand what to use here. If two 1000W toasters were to be connected in series to a dc power supply, what power supply voltage would be necessary for normal operation? Assume each toaster was designated to a 120V ac circuit...
  42. S

    Solve Power Supply Questions: Electrical Engineering Forum Help!

    Wow! An Electrical Engineering Forum! :!) Please help! I'm a newbie in the field, just got my degree last May (2005, BSEE). I focussed on computer engineering and can program the crap out of a micro-controller. Now I'm working on some automated test systems and have to work on a lot of...
  43. F

    What is the best way to get a 5V regulated power supply from a 12V transformer?

    Hi, this might not be electrical engineering, but I found no other forum to question about this. I'm trying to get a 5V regulated power supply from a 12V, 300mA transformer. I can't seem to get it to work. I'm using a 5V regulator, two 470 microfarad capacitors and electronic wire in a...
  44. Z

    What size capacitor do I need for my CO2 laser power supply rectifier?

    So I'm building a CO2 laser for fun, basically. I have a tube that requires 11-18KV DC to fire. Right now I have a 20A variac, a 15KV transformer (30ma out) and then I need to build a rectifier. I have a bag of "1A, 1000V" diodes. So far, I built a full-wave bridge rectifier out of them. I...
  45. M

    Nuclear Power Supply: How Much Is Left?

    Well we all hear of fossil fuels being depeleted soon. and the fact is that we don't have a lot of radioactive material around. So has anyone done a study on how much radioactive material is left that can be used in reactors. Including estimates on how long we have until that's through. Also...
  46. C

    Creating a Power Supply for a Capacitor Bank

    I am making a large capacitor bank (I guess not that big, but enough to kill you a couple times over) and I need a little help with charging it. I am using 450 volt 1200uf electrolytic capacitors. I have them in two sub banks of 4 wired in parallel, and connected to each other in series. I only...
  47. D

    Power Supply Caps: Why Do They Have High Voltage?

    why do power supplies like computer power supplies have high voltage caps?
  48. M

    Electrolytic Cell Power Supply

    I am working on trying to get a reliable power supply primarily for my Electrolytic Cell, and secondly for any other power supply needs that should come up. I have pretty much concluded that a computer power supply will suit me best. In the past, I hav been using a AT power supply, but I...
  49. M

    Replacing Power Supply - Advice on Wattage Needed

    With a loud pop and a puff of smoke my 300 W ATX power supply died last night and I find myself looking to quickly buy a new one. I was wondering if I should replace it with a higher power one. I ran this one for 3 year with most of this hardware without any noticeable problems. Rather than...
  50. K

    Power Supply from USB: Get Answers to Your Questions

    hi, I want to power a digital pen using a USB connected to the PC. What is the exact procedure for this...as in do i require any external circuitry? I also heard about this DTR pin which when permenantly enabled, acts as a power supply. can anyone enlighten me about these things? thanks.
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