Questions tagged [power-supply]

An electronic device that supplies electrical energy to a load. It can be AC or DC input. Typically DC output.

The term "power supply" is extremely broad, and covers a large variety of devices.

Some examples of common power supplies:

  • AC adapters, which convert AC from the mains to low-power DC loads (commonly referred to as 'wall-warts')
  • ATX PC power supplies, which convert AC from the mains to several regulated DC outputs to power computers and their peripherals
  • battery chargers, which vary the output voltage and current to charge batteries safely
  • inverters, which convert DC into mains-equivalent AC to power devices usually connected to the mains
  • DC-DC converters, which convert DC into higher (or lower) voltage DC
  • Linear regulators, which regulate DC into lower voltage DC without conversion
  • batteries, portable but limited amount of energy

Commonly used definitions:

  • load: a circuit that draws electrical power from a power supply (a computer, a light bulb, etc.)
  • mains: (generally) AC power provided by an electrical utility
  • rectification: conversion of AC to DC
  • converter: a circuit that changes voltage from one form to another (AC to DC) or converts DC to DC using a switching stage (DC -> AC -> DC)
  • PFC: power factor correction, which generally refers to a circuit that converts the mains AC into DC while keeping the input current sinusoidal and in-phase with the voltage (making the power supply load appear resistive to the mains)

Wikipedia power supply article

You are ok if your power supply can have the same voltage and the same or more current. The reference question for choosing a power supply is Choosing power supply, how to get the voltage and current ratings?

Common Switching-mode Power Supply(SMPS) Types:

  • Buck: A SMPS that will take in a higher voltage and step it down to a lower voltage. An inductor on the output rail of the power supply is characteristic of this topology.
  • Boost: A SMPS that will take in a lower voltage and step it up to a higher voltage. Generally, an Inductor in the input rail to the power supply is indicative of this topology.
  • Buck-Boost: A hybrid SMPS that is capable of both the buck and the boost topology. Generally, this will have an inductor on both the input rail and the output rail of the power supply in which only one of them is internally engaged at one point.
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What is the usage of the negative voltages on a PC motherboard?

What is the usage of theses negative voltages? Are they there only for backward compatibility? In nowadays PC power supplies, we have: +12V +5V +3.3V but also: -12V -5V But the current rating of the negative rails are much smaller than the…
Blup1980
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Benchtop power supplies: linear vs switching?

I'm looking into getting a decent benchtop power supply ($150-300) for hobby-level electronic design and testing. I don't want to modify or use a computer ATX supply because I want: Adjustable voltage Adjustable current Low noise/ripple Accuracy 1…
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Should I twist DC power and ground wires from a power supply?

Is it beneficial to twist the red/green power/ground wires from a low-voltage (~5V), relatively low current (1 to 5 A) switching, desktop power supply? This makes my wire bundle on a desk less chaotic, but will it reduce noise or provide any other…
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What are the ways to make a dual power supply from a single voltage source?

I have a function generator IC XR2206 from EXAR. It's application circuits uses dual power supply +/-9 volts. How can I make such a 9-0-9 dual supply from a single voltage source like a battery or an adapter?
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What are the use cases for the earth ground terminals in a bench power supply?

When I use bench power supply such as below: I use the red terminals as (+) and black terminals as (-) and also as ground. But the green terminal I never use and it is connected to mains earth ground. The PSU as a whole is already earth grounded…
ty_1917
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Regulated power supplies - how do they work?

I'm building a small audio amp (a current controlled varient of the szekeres design) and it apparently needs a very clean, regulated power source. Due to minimum parts order requirements, i'm going to end up with, amongst other things, a spare lm317…
Journeyman Geek
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What is the COM terminal on a DC Power Supply?

We have a HP E3631A power supply at my university's lab. There are 6 ports. My questions are as follows. What is the green port titled 240VDC Max? I was explained to an extent that it was the ground associated with the ground of the building. I'm…
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Why off-line power supplies are called so, like they are "off the line"?

My understanding is that "off the line" means "not on the line". For example an internet user is offline, meaning "not connected". However "Off-line power supplies" are directly connected to the grid (without line frequency transformer). Who coined…
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PC power supply bench breakout board. What is -12V used for?

I bought a useful PC power supply breakout board, fused. It has the following outputs: -12V +12V +5V +3.3 What is -12V and how would I use it? The -12V has its own negative.
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Why must this DIY lab bench power supply be powered by an AC supply?

Technical Specifications: Input Voltage: 24 V alternating (max) Input Current: 3 A (max) Output Voltage: 0 - 30 V, could be regulated continuously Output Limit Current: 2 mA - 3 A, could be regulated continuously Output Voltage Ripple: 0.01%…
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+/- 9V DC Power Supply

I am working on a simple audio mixer project. The op-amps I am using (LM741) take +9V and -9V inputs. I am currently getting this by wiring two 9V batteries together, connecting + on one to - of the other, and grounding the pair. This seems to work,…
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What is this canister at the top of a utility pole?

I'm currently in Manuel Antonio, Costa Rica. I'm living in a relatively off-the-beaten-track house and at the top of some of the utility poles leading to my house are these canisters (the light grey thing with "IC" on it): What is that? Is it a…
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3 Contact Laptop Power Supply

So I'm wondering if anyone has any information about the Dell power supplies which have 3 contacts on the barrel. I know the 3 are power, ground, and some sort of communication link. Does anyone know what the communication line is for and/or what…
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How do constant current power supplies work?

How do constant current power supplies work? For example I have a power supply that is constant voltage that can supply up to 5A and I have a 12V motor that takes ~500mA so I crank up the supply to 12v and my motor pulls ~500mA from the supply. But…
Dean
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Power Supply Rejection Ratio for Battery Powered Systems

Analog Devices just brought out several LDO regulators claiming double the power supply rejection ratio of competing devices, and targeting these devices at battery powered devices. However, I thought that batteries were quite noiseless, as opposed…
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