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. S

    Power supply voltage range design cost

    Today's switch mode power supplies for computers mostly have a nominal voltage range of 100 to 240 volts. Whatever the added cost of making them operate over that much of a range there is must be less than the cost of having separate products for the two major narrow voltage ranges used...
  2. F

    Searching for Automatically Switching DC Power Supply for Research

    Hi. Does anyone knows about a DC power supply that can switch between forward bias and reverse bias automatically? For example, I start it with forward bias, after 1 minute, it will automatically switch to reverse bias, and after another 1 minute, it will automatically switch to forward bias...
  3. K

    Help with a power supply (farnell G6 60a)

    Hi all, I'm brand new to the forum and dreadfully new to electronics in general, but am doing my best to learn and I figured this may be a good place to start. (ps - this is not homework..I'm not a student of an electrical engineering, just an enthusiast trying to learn :)). I'm trying to...
  4. Kawakaze

    Noise from unplugged power supply :S

    I have a ccd camera that I put a peltier element into, and there is noise from the power supply, even when it isn't plugged in. Just plugging the jack in gives noise, I tried the bypassing thing with a capacitor with no effect. Plugging the PSU in gives no change. I tried moving the power supply...
  5. F

    Calculating Voltage Ripple in a Full Wave Rectifier Circuit

    http://img683.imageshack.us/img683/5329/unledtw.png So its basically a power supply with a voltage regulator LM317T at the end. The question asked to find the voltage ripple across the capacitor. So I basically solved the peak voltage found which would be 12V * SQRT(2) = 17 volts...
  6. S

    Understanding Power Supply Ratings and Compatibility

    Hello i need a 9VAC 1.3A source but it's hard to come by... is there a way i can use a similar source? i don't know too much about this sort of thing but from what i understand the power output is more important than the individual current or voltage out... is that right? for example, my...
  7. U

    Can a high-Vdc power supply be an electrostatic generator?

    Hello all, I am interested in placing a static charge on a conductor by means of an electrical circuit. One way to do this is by means of a Van de Graaff generator which uses the triboelectric effect to generate net charges, then places them onto two conductors having equal but opposite...
  8. PainterGuy

    Some functions of power supply

    hi everyone, here is picture of power supply:-- http://img696.imageshack.us/img696/8841/powersupplyg.jpg at top it says power supply can give 3A. would this mean when resistance is 10 ohm is used and voltage is set at 30v. then current will be 3A. please tell me. what is the function...
  9. T

    Help me in selecting a power supply for conductivity measurements

    Hello all, For my project, I am trying to measure the solute concentration of water inside a porous ceramic plate (~2mm in diameter). I am using platinum electrodes. There are two ways I think I could possibly do this. 1) Place two electrodes on the sides of the porous disk 2) Place 4...
  10. L

    Convert Power Supply to 12V Lab Power Supply

    I want to convert my power supply into a "lab power supply" but a lot less simple. I just want a 12V output on it. The power supply has 2 12V rails. Is it possible to connect both rails to increase amperage? Thanks for you input.
  11. N

    How should I properly supply power to the DAC813?

    Hello, could someone please verify the proper way to supply power to this particular DAC chip: http://focus.ti.com/lit/ds/symlink/dac813.pdf Do I need to supply both +15 V and -15 V into +Vcc and -Vcc respectively? Or do I just supply +15 V to +Vcc and have the negative return lead of that...
  12. Drakkith

    Where Can I Find a Connector for a 40kv 15ma High Voltage Power Supply?

    Hey all, I've got a high voltage power supply that I need some sort of connector for. It's a 40kv 15ma output and the connector screws in over a hole that leads to an enclosed plastic tube with a metal rod about halfway down. Are these standard connectors or do i need to do something crazy to...
  13. J

    Can One Secondary Transformer Power Multiple Outputs on a DC Power Supply?

    I've been looking ahead in my textbooks and reading some stuff online, and there's some things I'd like to know about DC power supplies. The DC power supply we have at school has 3 independent outputs, 2 variable and one fixed. How would they be isolated from each other like that...
  14. P

    Dual Power Supply: Why Use +12/-12V?

    why do we use a dual power supply? Why, for instance, do we use +12 and -12 volt instead of just a 12 volt power supply.
  15. Hepth

    What Happens If a PC Power Supply is Maxed Out?

    I currently have a slim-line PC I bought real cheap. http://www.abcwarehouse.com/product_catalog/pc_proddetails.asp~prod_id~34788# I paid $200, not bad. Well, the case is Custom, as is the internal power supply. The video card is lacking, and I know there are quite a few pci-e...
  16. S

    Uninterrupted Power Supply (UPS)

    Hi, I have an ups used for my PC. I have just replaced his faulty battery and checked the output on battery operation with a multimeter.The reading are as follows: 1. Without load the ouput is about 184V. 2. With load the output is between 196V to206V. Can someone tell me if I use the ups...
  17. J

    Question on Evaluating a Power Supply

    I'm evaluating a wall-transformer type power supply used to power guitar effect pedals as a replacement for a 9V battery. It's rated at 9V and 2000 mA. I put resistive loads on it of (nominally) 16, 8 and 4.5 ohms, and made measurements with a Klein Tools MM1000 multi-meter. Here's what I...
  18. C

    How can I eliminate AC leakage in my power supply for optimal performance?

    Im using the 7809 IC to get 9v regulated dc supply. However, I'm also getting about 14v ac in the output as well. I've tried putting a notch filter tuned to 60hz to remove the ac voltage, but its still there. I'm using this power supply to power tl072 op amps and I'm worried that the ac voltage...
  19. S

    What happens when a power supply is has more volts but less amps than you need?

    Hi guys and gals, please forgive the lame-o title, first poster here! I recently picked up a pretty fierce interest in electronics and I've been doing plenty of reading and experimentation but I have a few questions that I'm hoping will land on generous ears. What follows is a "brain dump"...
  20. M

    Set Up Dual Line Bench Power Supply For Op Amp Testing

    This is a very silly question. I can't believe I have forgotten. I have a 30v bench power supply and I am looking to test an op-amp running at +/- 15v. I have a supply which has a negative output/ positive output and inbetween a green common/earth output. How do I wire them to produce the +/-...
  21. U

    How Can I Adjust Vcc to Correct a 10V Output on my Amp Power Supply?

    Hi, I'm trying to understand how to correct when you put Vcc as 10V your max output is like 9.18V. Is there a factor on the data sheet or what? I'm trying to build a bi-state multivibrator to generate a 10V peak value but it's being saturated. thanks.
  22. D

    Why use high frequency power supply for generating plasma?

    Why use high frequency power supply for generating plasma?? Hi everyone, I noticed that for the plasma ball common in science museum, power with high frequency should be used for generating so called plasma inside to give out colorful glow. But one thing I can't understand is why power supply...
  23. H

    Changing Frequency of AC Power Supply: Circuitry vs Generation

    Can anyone tell me what the most standard way of changing the frequency of an AC power supply is? Can it be done with circuitry or does the method of generation need to be set at the desired frequency?
  24. T

    Capacitor/Transformer Voltage Rating for a 12V Power Supply?

    Hello, About me...so you know where I am coming from. If you don't want to read, skip to the end-ish... I'd like to start off my saying that I know next to nothing about electronics although I am eagerly reading the All New Electronics Self-Teaching Guide right now and it is confusing but...
  25. R

    Choosing the Right Power Supply for Your M-Audio Keystation 61es MIDI Keyboard

    I need a power supply for my M-Audio Keystation 61es MIDI keyboard, and I think I might have one that will work for it. The user manual for the keyboard says this: But then their website is selling a 9v 500mA as the proper replacement...
  26. T

    Creating a simple DC power supply.

    Homework Statement In one of my labs for a circuit analysis class we are told to design a simple DC power supply. The power supply will have three outputs, +4.5V, -4.5V, and an adjustable output from 0-11V. I have already done most of this and the question I have is could you design this so...
  27. H

    Will this power supply work for my device?

    Will this power supply work for my device? URGENT! I have a Mini-fridge I need to get usable again. Recently, as of a few minutes ago, I opened up its power adapter to find that capacitors have burst and that would be the reason of the fridges death a few months ago. Given the mini-fridge is...
  28. N

    Design an OP AMP Power Supply for Audio Preamp

    Hello, I am trying to design a foundation for an audio preamp that is powered by a single 9V battery. I am successful so far except the single power supply part. I am using the voltage divider scheme to get a +4.5V and a -4.5V reference voltages. With no load the supply voltages are close to...
  29. M

    LC Circuit with DC power supply

    A circuit has a battery(V), Capacitor(C) and Inductor(L) connected in series. At t < 0, the switch is open and the capacitor has an initial charge of -800uC and Io = 0.0Amps.. When the switch is closed at t = 0, I want to know what happens here. I only understand an LC circuit where there is...
  30. L

    Switchmode power supply question

    Why are SMPS smaller than linear power supplies? I understand when you switch at high frequency, the transformer,inductor and capacitor size reduces. Usually, there are 2 transformers in a smps. One at the AC input and one after switching. How do they rectify the 60Hz using the first...
  31. J

    Power Supply for EE Student Experiments at Home

    I am an EE student and would like to get my own power supply so I can experiment at home. I saw these two power supplies at frys and was wondering if they are any good. One is 0-30V 0-3A and the other is 0-60v 0-1.5A. I would like to experiment with making audio amplifiers. Which one of these...
  32. V

    Power supply - Importance of amp Rating?

    Power supply -- Importance of amp Rating?? Hello all: I have a TV tuner that requires a DC 7.5 volt, 500 ma power supply. I have a 110 V input power supply rated at 7.5 V DC 1,000 ma. Can I safely use this powersupply with the tuner. Analogy: I can plug a 3.5 am vacuum cleaner into a 15...
  33. A

    Power Supply Alternatives for an Electromagnet

    Homework Statement For an electromagnet that is just made up of wires and a core, what power supply can I use other than batteries that let me adjust the volts? Can you explian in detail? Homework Equations none The Attempt at a Solution I have already looked on the...
  34. A

    Replacing a Wall Wart Power Supply

    Assuming I have the same voltage, correct polarity, and sufficient current, can I generally replace any class 2 power supply with any other? This will be used for common household electronics. In particular, when researching power supplies, I see specifications for ripple, noise, setup, rise...
  35. T

    Laptop Power Supply: How to Charge Battery Externally

    Greetings, Does anyone know how to use a laptop's charger to externally charge its battery? I am using a battery from an old DELL laptop to power my handheld radio. I wish to use the charger that came with the computer to rejuvenate the battery, however, the charger circuitry is smarter...
  36. S

    Power supply input discharge voltage

    I would appreciate any help, opinions or explanations on this as I am receiveing many different views currently. I measure the discharge voltage of a single power supply (laptop ac charger) using a digital chart recorder. On a trial and error basis I achieve the data as close as possible to...
  37. T

    Designing a 550 V, 3A DC power supply using a multiplier circuit

    Ok so i received the suggestion to get such a power supply by rigging a variac to a bridge rectifier, but variacs are rather expensive, so after some snooping around i came around this site: http://www.scribd.com/doc/9779212/ebook-free-energy-50000-vdc-power-supply they basically just use...
  38. A

    Bridge rectifier and symmetric power supply

    Could some one explain how a bridge rectifier works with a diagram and its mathematics? Also please explain how a center tap transformer and a bridge rectifier are used to provide a symmetric power supply. I have the Ckt Diagram for that but I cannot understand its working. thanks...
  39. D

    Figuring 12V 3A DC Power Supply Capacitance

    I want to know if I am figuring correctly. I am putting together a 12 volt 3 amp DC power supply. The formula in the instructions is C = Tc / R. I figured the required cap to be 20,750 uf. When I went to a couple of supply catalogs to check the price for the cap I found that no one had had a...
  40. D

    What is the best power supply for a peltier-based water cooling unit?

    Hi, I'm new here so I apologize if my question isn't composed appropriately. I’m currently designing water cooling unit, which is a component of a larger project, that utilizes peltier plates as a heat pump to displace the energy from the water. To cool the peltier plates themselves I...
  41. S

    How can i figure the current loss of a power supply?

    OK, so if I'm inputting 120V ac @ 1.5A equals 180W and my output is 19V dc @ 3.16A equals 60.04W simple subtraction says 116W is left. that can't be right can it? am i doing this wrong or am i actually losing 116W of power?
  42. H

    Can I Safely Use 3.16 Amps with My AC/DC Laptop Power Supply?

    Just a quick question for you guys out there. I have an AC/DC laptop power supply. I was thinking of using it for a few projects. Th power supply's output is 19 volts and 3.16 amps. My question is is 3.16 amps the max current that the power supply can take without frying? I mean the number of...
  43. C

    How to reproduce a battery with a power supply

    I am expermenting with a sperical metallic neodymium magnet ball that spins like a DC motor when I hook up a + or - charge up to the north or south pole of the ball and then hook up the other charge to the equator of the ball. I have only used alkaline batteries and it works with a AA 1.5 volt...
  44. wolram

    Circuit diagram for a power supply that outputs about 25kv

    Does anyone have a circuit diagram for a power supply that outputs about 25kv at a few mA dc. 25kv is just a ball park figure it could be 22 or 30 kv, or even better adjustable from 22 to 30. Input would be 230v ac Thanks.
  45. C

    Constructing My First Power Supply: Investigating AC Components

    Ive recently completed a project in microcontrollers (my first project with uc's actually) and I built a power supply which gives me 12v and 5v dc. I use a transformer to step the voltage down to 12v AC from mains and then the 12v AC is converted to 12v dc using a bridge rectifier with a...
  46. P

    Full-Wave Bridge Rectifier Filter + Regulator DC Power supply

    http://img104.imageshack.us/img104/3557/1234uyq.jpg Ok, there are a few calculations on this problem that I am having difficulty with. This is a past homework assignment which is why the answers are filled in. They are all correct. Anyways I approached the problem in this manner: V...
  47. N

    Powering 150 LEDs with a 12v,1A Power Supply

    I am trying to figure out a better way to power 150 leds that need 3.4v and 20mA with a 12v,1A power supply. Right now the best way I can think of is have 3 leds in series and a 100 ohm resistor at the end(50 times). Is their any better way so I can use less resistors
  48. A

    Can a common 9V power supply be used as a -9V supply?

    So if you have something like this: https://www.amazon.com/dp/B0002H07CW/?tag=pfamazon01-20 can you use it as a -9V supply? My circuit requires a +9V and a -9V supply, and since I am having issues finding fixed +/-9V supplies, i was wondering if i could just use a 9V supply for the +9V, and...
  49. A

    Question about wiring from a power supply

    I'm considering using this power supply: http://salestores.com/pr30trouposu2.html now.. if i wanted to get a voltage value of -5V into a circuit (such as http://www.tekscan.com/images/flexi-circuit-new.jpg" ), could i just put a wire from the (-) terminal of the power supply, to the Vt? And...
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