Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [ac-dc]

Questions regarding the safe and effecient design and implementation of AC voltage to DC voltage supplies. Typically Mains to some lower DC voltage.

Questions regarding the safe and effecient design and implementation of AC voltage to DC voltage supplies. Typically Mains to some lower DC voltage.

Not about the band of the same name.

414 questions
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Computer power supplies usually have higher efficiency on 230V than on 115V. Why?

As seen here in the example, this particular power supply (and most others too) has higher efficiency when running on 230V. Given that computer power supplies are usually required to output a combination of 12V, 5V, and 3.3V DC, why is it that…
cyqsimon
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Help me understand the relationship between positive, negative, neutral and ground in AC and DC

This question stems from notations on schematics and seemingly conflicting information I'm seeing. I suspect that I'm seeing different vernacular for the same concepts--but I'm in a place where no one's ever told me that an "elevator" is a "lift".…
dwwilson66
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If we could start our electrical grid from scratch with today's technology, which would be the most efficient choice? AC or DC?

Lately, I’ve been reading about the many advantages of HVDC transmission systems for long distance transmission, undersea links, and others. The historical reason of why AC was picked over DC was mostly due to the invention of the transformer, which…
Jota
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Why is this power adapter transformerless?

I saw a battery charger that converts 220V AC to 6V DC without a transformer. Now I am wondering why many (if not all) power adapters are using a transformer, is it about efficiency or about drifting over time? Update: This circuit is inside of…
Jim
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Does this AC to DC + breadboard setup have the ability to kill/severely hurt me?

I'm currently building a PC peripheral that uses an AC to DC converter to power a set of DC fans. I'm not a trained EE or electrician, so I want to make sure I'm not putting myself a risk with this setup. Essentially, I have the AC to DC converter…
DonutGaz
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How do phone chargers have variable input voltage with constant output voltage?

My basic understanding is that a transformer can step down a voltage by the ratio of the primary and secondary windings, since this is a ratio the output is not constant. Thus my question is, how are chargers like the apple phone charger (a…
DiscreteTomatoes
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Bridge rectifier: 4 diodes vs. single chip?

I notice (among the DIY audio enthusiasts at least) that when it comes time to design a power supply for an amplifier, DAC or whatever that the parts list will inevitably include something like "4 x MUR860 diodes" for the sake of building a full…
abza
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MOSFET failure in a high power AC-DC SMPS buck converter

I've made a AC-DC step down buck converter that converts 220 VAC to a variable 45 to 70 VDC at 5 to 10 A to charge a Li-Ion battery. I'm currently using ESP32 to drive a MOSFET driver (IR2110) to drive my NMOS placed at the high side of the circuit.…
Kevin
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Can a 50 Hz, 220 VAC transformer work on 40 Hz, 180VAC?

I am designing an AC to DC converter. My power source is a single phase synchronous alternator that has a voltage range of 170~260 VAC and a frequency of 40~60 Hz. Can i use a transformer designed on 50 Hz and 220 VAC to work on my alternator specs…
Mahmoud T. Abuzayed
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Is it safe to use a DC power adapter that isn't UL Listed or CSA certified?

I picked up a 9V switching DC adapter from SparkFun a while back, but I've been hesitant to use it because it doesn't have any of the usual "safety" approvals that you normally see on power adapters (UL listed, CSA approved, etc.) Is this just…
Owen Thomas
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Is it possible to step down 240 AC to 5 DC without transformer?

Microcontroller which is controlling mains voltage circuit requires 5 volts to operate. Is it realistic to use diode bridge followed by capacitor to straighten the ac wave and then use voltage divider to get 5 volts from 240 without actually burning…
flowian
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Connecting two DC wallwarts in series - to produce dual DC supply

I have two 9 V, 300 mA wallwarts and would like to connect them in series to produce +9 V, 0 V and -9 V. This can be done with two 9 V batteries (as seen below), but can I do this with two non-identical wallwarts?
Jazzmarazz
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AC adapter: Input power vs Output power

When I look at, let's say an iPad AC adapter, the input/output rating on the charger states: Input: 100-240V 0.45A (AC) Output: 5.1V 2.1A (DC) I know that the input and output ratings are maximum. The AC voltage in my country is 230V. Through a…
Skaty
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Converting universal AC to 3.3v DC @ 0.1A

There's a bunch of topics around this but i haven't found something that fits my requirements. I'd imagine this is a fairly common thing though so any pointers would be appreciated Basically i want to design a circuit that can use mains power…
Antti
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Purpose of capacitor across transformer in AC-DC power supply?

I have been looking to buy a AC-DC 5v power supply module to power a mains relay in a circuit I am making. I came across a couple of different models on eBay and am trying to understand their basic working design. This one in particular has good…
codebeard
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