What is Power supply: Definition and 299 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. E

    Variable vs constant power supply

    I have a CCTV camera using the ordinary 12 volts AC to DC adaptor that has higher voltage (like 15 volt) when there is no load. I decided to buy a Meanwell adaptor but the datasheet (below) I got doesn't give the no load voltage. What do you call power adaptor in which the voltage is higher at...
  2. A

    Sizing an Isolation Transformer for a DC Power Supply

    Good afternoon, How should an upstream isolation transformer be sized for a dc power supply? For example, if we have a power supply with the following specs: Input Voltage: 120 VAC Input Current: 2 Amps Inrush Current: 22 Amps Efficiency: 90% Power Factor: 0.55 Output Voltage: 24 VDC Output...
  3. I

    Should the power supply float or be grounded?

    I have read pros and cons for both, but would like to hear what people have to say. I can build a simple power supply for a project that supplies 15v that is isolated from earth ground by using the output from a step-down transformer. I can also put one together that shares earth ground. Which...
  4. E

    NPN transistor overheating even when used with appropriate parameters

    I have been trying to build a simple Current control circuit using a NPN TIP35C transistor but have run into the problem of it constantly over heating and being destroyed. The transistor is the only component that heats up whilst it is on. The supply voltage is 10V, well below the Max and at the...
  5. J

    Fried my power supply by doing a bad thing

    I have a Multicomp 0-30V 0-5 amp power supply. I did some tests using it as a battery charger. It worked very well the first few times, then I accidently hooked it up backwards and killed it. There was light sparking when this happened. No fuses blew. It powers up normally, and I can...
  6. D

    Uninterruptible power supply output specifications

    Why do some UPSs have both Volt-amp and watt rating? According to APC, the connected load shouldn't exceed the UPS's VA and watt rating. Why? If I had a UPS with 1000VA and 500W rating, why can't it power a load consuming 1000VA @ 900W? If a UPS can output 1000VA, why does it care how much...
  7. PhysicsTest

    Negative Power Supply Clarification

    I am confused with the negative voltage supply connections in electric circuit. If i have circuit as below with -5V source it is same as below In the 2nd circuit the 5V is directly shorted with the ground, does it mean the circuit is not correct? Am i missing something? Please advise.
  8. V

    DC-DC conv. Ripple affecting Speech Recognition - Capacitance multiplier

    Into a project I am working is use 12Vdc SMPS to power an audio amplifier and some more components. We have no “noise” on that stage. Then I use a step down converter to convert the 12V to 5V and power a mic preamplifier (Respeaker – usb Mic array) and a development board. There is a lot of...
  9. bluesteels

    A.C. power supply voltage amplitude questions

    I know that the answer for A is 31.82. But when i look up B why is it zero? can someone explain please thank you
  10. naviakam

    Troubleshooting 30kV Power Supply: Possible Problems and Solutions

    I am using a power supply (30 kV, 20 kHz) to discharge in air between two electrodes separated by an insulator. For 30 kV applied voltage, oscilloscope shows only 6 kV, and no discharge occurs. What are possible problems and solutions?
  11. naviakam

    I Plasma device power supply

    In a plasma device, the plasma is generated by applying high voltage in a gas. What are the specifications for the power supply producing such plasma? The output must be AC or DC? Pulsed or not? What are the current, voltage, etc...?
  12. T

    Key fob only works on battery and not power supply. What?

    Yesterday the batteries died on my key fob and I didn't have the appropriate batteries to replace them. I thought I could use my power supply to operate the key fob to open the car door but it did not work. I thought that it may be caused by a noisy power supply at the higher frequency range of...
  13. BiGyElLoWhAt

    Building a Low Power DiY marine bluetooth speaker set

    My dad has been asking about some speakers for his boat, something that will move a bit of air, not too big though. I'm thinking 1x12. He also wants it bluetooth and powered externally, so it doesn't drain the boat battery. So I'm thinking 1x12 speaker in a small box that can fit inside the...
  14. V

    Handle Peak Inrush Current of a BLDC Motor to protect the Power Supply

    I have to use a BLDC motor combined with a BLDC motor driver (X-NUCLEO-IHM08M1) The motor has a rated current of 7.3A. So i am planning to use a 36VDC 13.9A power supply (SMPS). The problem is that the PS that i want to use has a "HICCUP mode" for overload protection and not a "constant current...
  15. ghowriter

    How to make a custom UPS using an old PC power supply and 18650 batteries?

    Yes, this is a question. I already converted an old PC power supply (350 Watt) to replace the bower bricks for my Internet modem and router. What I would like to do now is install a 2-3 hour mini-UPS in the mix so I can remove it from my computer's UPS. I have spent days online scouring the web...
  16. gumby4231

    12V Tractor Battery supply: Losing Power Supply

    I want to mount a camera on the front of a tractor(Sony RX0M2, similar to a gopro). The camera will eventually be used for image processing. A PQ-12 micro linear servo (see here) will be used to turn the camera on/off. It is being run by a Raspberry Pi 4B. All components in this project will be...
  17. M

    How to calculate the efficiency of a switch mode power supply?

    I know how to calculate the power output and input by analyzing the current in put and output with multimeters and using the formula P=VI. But P_out is obviously incomparably smaller than P_in so the efficiency would suck this way. Is there a better way to do this??
  18. trurle

    AC-DC Power Supply Modules: Non-Isolated Topology

    In AC-DC power supply modules, having non-isolated power converter topology may result in input "Line" (hot wire) been assigned to "Vss" (lower voltage rail) at output of power supply module, and N (neutral) assigned to Vdd (upper power rail). Inside single system, this usually does not results...
  19. S

    Strange problem: Replacing a battery w/ a DC power supply

    Hey everyone, So I'm trying to figure out what could be causing this problem: I have a DEWENWILS Wireless Remote Wall Switch which takes a 12V battery 60 mAh(23A battery), when I replace the battery with a 12V 500 mA DC power supply, the unit stops working properly. I'm able to use the Power...
  20. P

    Potential of the terminals on a DC power supply

    Summary: Hi there On a 12VDC transformer we use at school. Is the positive terminal +6V above ground potential and the negative terminal -6V below ground potential? Thank You Hi there On a 12VDC transformer we use at school. Is the positive terminal +6V above ground potential and the negative...
  21. kolleamm

    High current power supply for servos? 40+ amps

    So I've basically built a robot that has a lot of servo motors. 14 of them can draw up to 3 amps each(max)(usually 1 amp average) at 4.8 to 7 volts. What's my best option to power it? The power source doesn't need to be connected to the robot, so weight shouldn't be an issue. My best guess is...
  22. M

    Overvoltage on the power supply to compressor motors

    Hope you may help me to understand how detrimental to compressor motor would be if it operated at voltages exceeding the manufacturer's specified 400V by 12%? so 448V. I have vendor engineers saying since it exceeds 10% they cannot safely run the plant and of course the voltage monitoring relay...
  23. A

    1-10 kV power supply recommendations DIY electrostatic motors

    I am trying some projects that involve building some very simple electrostatic motors. I attached below figures of the kind of electrostatic motors I am trying to make. What I can't figure out is what kind of high-voltage power supply I should use, presumably 1000 to 10,000 volts is what these...
  24. G

    Power supply for testing: Variac or isolation transformer first?

    This is for safely powering up devices being tested/repaired. Supply is 240V rms single phase, protected by 32A MCB and 30 mA RCD/GFCI, then fused at 13A. There doesn’t seem to be a consensus online, and my EE and repair books just say I need both, without specifying order. I think the...
  25. F

    Query about the time average of an AC power supply

    Hi there, I have a query about electric power in AC systems. I am Chilean, and over here the power supply is 220 V (rms) at 50 Hz. Some countries use voltages in the range 200-230, but others use 110 V or so, at frequencies of 60 Hz. There is no uniqueness, but all work. My question is...
  26. K

    Electrical Help with making a heating element with a 3 phase power supply

    hi everyone. my uncle currently has a big "cylindrical rolling cooking pot" (imagine a cement mixer with burners at the bottom) that he uses to cook his stuff, ie sesame seeds. this cooking pot currently runs on gas. as he has been facing some issues with the gas supplier, he intends to...
  27. EEristavi

    Why a DC power supply doesn't have a voltage with respect to ground?

    I see that DC power supply have voltage between it's + & - and its 24V. However, there is no voltage with ground. I don't understand - if device's "point" has some potential, why doesn't it give some voltage with ground (which has ~0 potential) I tried this with phoenix contact...
  28. M

    What should I consider when searching for a high voltage power supply?

    I'm looking for a high voltage power supply. I have no experience with such a power supply, nor with all the terms or specifications used for such tools, so I'm looking for general suggestions to what to look for. I want to generate an electric field or potential field between two points a few...
  29. TechTree

    Share a power supply between two devices

    Hello, I have recently converted an old bluetooth speaker into a Aux input device for a guitar amplifier. You can see how I converted it here. So now I'm trying to power both the bluetooth device and the guitar amplifier using the original amplifier's power supply. Here is the power that each...
  30. F

    How to use a bench power supply

    Hello, I understand that a bench power supply (see picture below) is mainly used as a constant voltage source: once the load is connected to the two terminals, we set voltage ##V_{supply}## by turning the voltage knobs on the right and find that voltage across the load. At the same time, the...
  31. ajohns2000

    Remote control of a Walker Scientific Magnet & Power Supply

    Hello and good day. I am currently involved in research that seeks to utilized a Walker Scientific power supply and magnetic. The system is old but functional. We seek to utilize the magnet in order to conduct some low temperature experiments. We need information on this power supply, of which...
  32. K

    Uninterruptible Power Supply

    Let's say you have a UPS 550 Watts (1100 VA). How much current or watts does the unit itself used? This is important when your source itself is limited by the wiring.. let's say all your computers total 500 Watts and the wiring is sized for roughly that.. Would the UPS draw more current or...
  33. Mzzed

    Creating oscillations on the output of a DC power supply

    Is there some common parameter for DC power supplies that provides the maximum oscillation amplitude allowable at the output? For some context - I would like to generate an oscillating signal powered by a DC power supply, but to prevent most of the oscillations reaching the DC supply I am going...
  34. G

    Selecting an MOV for a power supply

    I have a 30V 5A variable linear power supply, which has failed twice from transients killing the LM358 quad op-amp IC that controls the output. These transients are from driving things like a car ignition coil, for making an electric fence energiser. Simply replacing the LM358 gets it going...
  35. J

    Schematic for a Tenma DC Power Supply 705-72

    I am searching for a legible schematic diagram for a Tenma 705-72 DC laboratory power supply. Each of its two channels uses a LM723 regulator and a pair of 2N3055 power transistors. One of the channels operates normally; the second channel puts out the maximum voltage (37 volts). Any help...
  36. Mzzed

    Understanding Dual Output Zener PSU

    I am struggling to understand the voltages present in the circuit below. So as stated in the diagram, there is 30V AC at the secondary of the transformer, this is equivalent of 42.4Vpeak. The bridge rectifier changes this to DC and drops the voltage down to roughly 26.3Vpeak DC where each diode...
  37. G

    How to get the fuse rating you need for a DC power supply

    building a DC supply with a load voltage of 3.3V and load current of 3.3mA. all the books and schematics I'm seeing is that they're putting the fuse in the primary of the transformer, why? if i were to fuse the primary as well how do i get the rating of the fuse that i'll need? its said in my...
  38. W

    Designing a linear DC power supply

    Homework Statement Design, giving the necessary ratings and characteristics necessary for the transformer, bridge rectifier, reservoir capacitor and regulator, a 12 V, 2 A regulated power supply. Also identify any heat sink requirements. The available mains supply is 230 V ±10% @ 50 Hz...
  39. D

    Help intagrating hertzmeter into analog linear power supply

    First off I'm not an engineer nor do I have a electronics background. I have an old Linear (HP 6284A Power Supply). I would like to be able to display Hz/CPS. I need to measure the speed of a tattoo machine. (basically two coils that make and break connection through out its use. From what...
  40. G

    Linear DC power supply repair

    Lavolta BPS 305 0-30V and 0-5A. I was showing a young lad how you can energise a car ignition coil and get a spark on the output, and that this effect can be improved by adding a cap in parallel which forms a crude LC oscillator etc when the unit died. Silly, I know, but we got a bit carried...
  41. P

    Inductor behaviour in an AC power supply

    what is actually happening when an Inductor is connected with an ac source.(i mean at the very instant of connection is made).i know emf will be induced due to change in current.(curl of E is =-time derivative of B)here my confusion is,inorder to induce emf,current should flow first,then who...
  42. Anugrah_kora

    Power Supply Problem: 19V 3A Laptop Charger + Solenoid

    I've got an old laptop charger 19v 3A for my solenoid. I used a multimeter to check the charger without and with load. I used a solenoid of insulated 22gauge of approx 150 turns as the load. On my first try without any load, it gave 20v DC on the multimeter. When I connected the load and...
  43. T

    Filtering an LED light's power supply

    Hi, Out of interest, today I was mucking around with a 160W LED, 240V, 50hz, outdoor light. I looked at the Power Factor (it was 0.96) and the THD was 14.something %. I then wondered what would happen if I put a capacitor in parallel with the light. It was a three phase 90uF cap, so since they...
  44. Anugrah_kora

    Connecting solenoids to power supply

    For a project,we thought of making solenoid engine. We made everythig by hand, including the DC power supply. The power supply worked very well, it's puts out like 20v 1A, and it was fine still after testing it for a long time connected to DC motor. When we connected it to a solenoid coil...
  45. B

    Power supply for multiple devices -- effects on accuracy

    Hi, For my project I am plotting a Force vs Displacement graph using 2 analog inputs which are going to a DAQ. The two analog inputs are coming from; -A 5k potentiometer (for the displacement) -A 1000 lb load cell sensor (for the force) I would like to use a regulated 12V DC (1Amp) power...
  46. S

    Using this power level indicator to measure a power supply voltage

    In this project, I am using the https://www.amazon.com/dp/B005W09XYW/?tag=pfamazon01-20 as a power supply, but in my project, if my device shuts off suddenly without shutting off properly, it would require me to reboot the entire system as it won't work anymore. So I decided to use this power...
  47. F

    How Can I Use a Power Supply as Both a Voltage and Current Source?

    Hello, Certain power supplies can be both a voltage source or a current source. a) Voltage source: We set the voltage to a specific value we like and change load resistor. The current will vary (get smaller for larger R) but the voltage will not vary. To make the power supply a voltage source, I...
  48. T

    Switch Mode DC-DC step-down PSU design troubleshooting

    I am working on a switch mode psu in step down configuration with the key components being: LM2592 (adj) http://www.ti.com/lit/ds/symlink/lm2592hv.pdf 530-PC-24-1000 http://www.mouser.com/ds/2/643/PC-594199.pdf GSIB-25 http://www.vishay.com/docs/88646/gsib25xx.pdf Using a slightly modified...
  49. Helmholtzerton

    Eval op amp achieves +/- power from single power supply?

    Picture for reference is below. I'm confused as to how this is able to receive a differential voltage of +/- from a single power supply. (Yes, I know the picture says dual power supply.) Normally I have to short the negative to ground on one side of a dual power supply, and short the positive...