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.

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Step down transformer alternatives

Does anyone know if I can use a Quam TBL 25 volt 4 watt audio transformer to step down 120 volts to 12 volts, later to be rectified to a 12 volt dc power supply? I know 12 volt power supplys are ...
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1answer
56 views

What is the power consumption of a 12V adapter running 4 CPU fans?

I have a quick question here. I am not a ECE guy and just a hobbyist trying to tinker while quarantined. I have 4 CPU fans (120mm) laying around and I'm trying to re-purpose them as a small fan. ...
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26 views

Techniques for measuring the ripple current of SMD electrolytic capacitors

I am currently creating a test plan for an AC/DC converter (90VAC...264VAC -> 12VDC) I've been working on. Since the output electrolytic capacitors are of SMD type, I am trying to come up with ...
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18 views

Using an ac adaptor for a dc only tv [closed]

I have a 12 V 1.4 A max dc only TV. How do I get the right ac to dc adaptor for it. I have a ac to dc adaptor for another TV but I am afraid it might blow the solar TV if I use it.
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where to find exact definition of i/p and o/p as used to define insulation resistance for AC DC converter?

Most AC DC converter datasheet use I/p and O/P to define insulation resistance I am looking for the exact definition of these parameters as used in this context ( I know their definition for ...
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1answer
61 views

What does it mean for a power supply to have an output range?

I had a power supply blow and I replaced it with one from the same company with the same model number. The new supply has lightly different specification than the old supply. Oddly (to me) it gives ...
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1answer
44 views

Full charged 12V battery with AC converter “empty” within one second - voltage drops, converter beeps

I have the following setup for solar power, which worked well until recently: solar panel <--> solar charge controller <--> small (car) battery <--> converter: 12V DC to 220V AC <--> my ...
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37 views

Need help wiring a power supply (UK)

First time here so apologies if this question is in the wrong place. Also i'm a bit of an amateur with this sort of things to go easy on me. I've bought a power supply to power a DC charger for LiPo ...
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30 views

Use old battery pack charger as DC power supply?

I have an old charger for NiCd battery packs. It is labeled with: Input: 230 V~, 50/60 Hz, 33 W Output: 4.8 - 12 V DC, 1.4 A I opened it and found a transformer and two circuit boards. I made a ...
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2answers
100 views

AC TO DC Converter IC

I am using a small circuit which needs 5V DC input and total current consumption of the circuit is 300mA. I have been using the small size ac to dc converter modules, but now i am searching for a ...
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1answer
42 views

AC-DC Switching Power adapter Unstable Voltage [closed]

I recently bought a AC-DC (14V DC, 3A) Power Supply on eBay to power a Samsung Monitor, and it does power on my monitor. It is not the monitor because another power adapter I have works with it. ...
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3answers
101 views

Powering small DC load ( 1W ) using 220V AC supply

I am trying to design a small control circuit for controlling large currents (not too large, around 200W, AC 50Hz). I have kept in the AC circuit isolated from the DC control circuit. But the problem ...
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2answers
108 views

Is It Posible To Have Step Up Power Supply Without a Transformer?

I am trying to design a high voltage low current power supply. My purpose is to design it without a transformer. For example circuit like this : My input is 220V AC after this circuit I am going to ...
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1answer
91 views

misunderstanding of Voltage output of a 3-phase rectifier

I simulated a 3 phase rectifier : I obtained V1 and V2 as plotted below : I dont understand that waveform as i'm supposed to obtain a DC voltage. Can someone explain me how it comes that i got ...
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46 views

How to ground external AC voltage (18V) to Arduino?

I have a project where I need to read 0-18 Volts AC in Arduino's input (0-5V DC). So I did a circuit with a diode (half wave bridge), voltage divider, and a RC circuit where I tested some values for ...
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2answers
68 views

Positive and negative rail for op amp circuit

I need a positive and negative rail to power an op amp Since it's an op amp for a voltage reference, would using a circuit like this one be enough? Input voltage is unregulated 37 volts, with 4.7k ...
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3answers
167 views

Discrete linear voltage regulator

I am trying to make a discrete component linear power supply. This schematic seemingly works but it doesn't work when I build it on my breadboard. I am taking 110 volts through a transformer down to ...
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1answer
81 views

AC to DC conversion: is this an appropriate implementation?

I understand that a 20v AC converter supplies 20V RMS AC. I wish to convert this to 20v DC and so have drawn up a schematic for this which includes: the AC to DC conversion, regulation, smoothing, and ...
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1answer
42 views

Output current and voltage levels regulation in ac/dc adapter

On the picture below is the output circuit of AC/DC adapter. I understand how voltage level contol works, but I don't understand how exactly current limitation works and how should I calculate ...
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2answers
39 views

Is this a reference of an AC/DC REGULATED adaptor?

I need to choose an 230 VAC / 12 VDC converter which is regulated, that-is-to-say I need the voltage to be 12 V with a current of 0 to 5 A. I found this one because it is the cheapest (price really ...
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0answers
87 views

Flyback converter with dual outputs (12V / 5V)

I came across the following flyback converter circuit, which has a dual output (12V and 5V), but I am unable to figure out why the secondary windings are connected in series. Based on the datasheet ...
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50 views

Energy Meter power supply advice/help

I've been assigned to start working on a smart energy meter project, it's been like 10 years since I put any work in AC. I would be sincerely grateful for any constructive advice. Now the 3-phase ...
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3answers
6k views

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 ...
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1answer
74 views

How to choose AC/DC adapter - high voltage low current vs low voltage high current

I got an LED light kit, 2 lights, each takes 60W, at 12-30V. I'm planning to use these lights separately, and need to choose between: 12V, 5A adapter 24V, 2.5A adapter Both will give me 60W, but ...
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2answers
55 views

How do I safely connect a light switch button to the secondary side on a board?

I designed a special light controller board. It has a primary side that is connected to AC 230V. There are a certified AC/DC converter module and a relais, bridging the air gap between the primary and ...
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32 views

Can I use AC voltage from myRIO to power stepper motor?

I am using easydriver and arduino for a stepper motor provided on this website The motor is 17HS3401S Stepper Motor and I think this is the correct datasheet found on the internet for the same. ...
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2answers
74 views

Laying out power electronics on analog signal board, practical advice

to keep this brief I am designing some audio circuitry and also need to design the power supply. The barrel jack in the schematic below sees 18VAC and I am converting that to +/-15V DC rails. So to ...
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41 views

Power Supply Design 230 AC to 80V DC - multisim and real components

I am an young student that was tasked to build a power supply which will convert single phase 230V AC into 80V DC to test specific DC motors (custom made). I only know that under normal operation and ...
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1answer
35 views

Protection circuitry for AC/DC converter

I'm using the RAC02-GB (Datasheet) as an AC/DC converter and I'm confused about the protection circuit they included in the datasheet: I want to make sure the AC/DC converter has the proper external ...
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68 views

Why does rectifier output is showing DC instead of pulsating DC

I am using below circuit for PFC. Before connecting coupled inductor's auxiliary output to the IC's Vcc, I wanted to make sure that it is coming properly or not. So when I probed the red dot in the ...
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2answers
72 views

Determine the resistor required for a circuit [closed]

If I want to supply power to a device that is rated for about 2V using a DC source of 12V. How can I find the resistor o should use.
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2answers
86 views

AC/DC Converters in Series with the Same AC Source

Would it be safe to connect two identical AC/DC converters in series if they share the same AC source? My concern is that the negative DC output is grounded somewhere in the converters causing the ...
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2answers
49 views

Can this receptacle power this power supply? [closed]

My car has a wall-style AC receptacle in it. It is merely marked 110V 150W. It is not mentioned in the owner’s manual. I’m curious if it can safely power this laptop power supply:
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67 views

PFC boost converter is not stepping up the voltage

I am making a PFC circuit for AC-DC converter. I am facing a weird issue. As per my design the output of the circuit should be 390VDC, but I am getting 311VDCrms with ringing (overshoot 360V, ...
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4answers
1k views

Converting 8V AC to 8V DC - bridge rectifier gets very hot while idling

I am tinkering with an Arduino and recently had to convert 8V AC to 5V DC in order to run it. The project is a custom doorbell, which gets the power from the doorbell transformer (transformer is ...
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0answers
35 views

AC adapter won't power fan at full speed [duplicate]

I have a spare 92mm case fan rated 12V and ~600mA I've used to build a solder fume extractor. When I was prototyping it, I tested the fan with a 12V 2.5A AC adapter and it worked fine, ran at full ...
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83 views

Astable 555 used for AC to DC Halfwave to DC stable conversion, is what I have done correct?

I have this falstad-circuit: And here it is per request, as a SCH file screen: I'm trying to use a 555 astable to convert a variable AC with maximum of 12V (coming from Bicycle Hub) to 8VDC, ...
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94 views

Use Triac as SMPS to get DC voltage

I want n 12V 1A supply for a project. I want a transformer-less topology. I was reading and experimenting with readily available traic based dimmers. They use phase control to cut the input voltage ...
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2answers
486 views

How to find the right smoothing capacitor for rectification circuit

I am creating a power supply which will need to convert the 24vac to 5vdc. I am thinking of using a rectifier to convert ac to dc, then a capacitor to smooth out the voltage, then an LM2596-5 to drop ...
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3answers
290 views

Why aren't non-isolated DC-DC converters made for high wattage applications?

I am new to electronics. I am presently studying DC to DC converters. One thing I noticed is that most of the people are using isolated stepdown converters like half bridge, full bridge, or resonant ...
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1answer
85 views

(230v)AC-DC(12v) wall adapter flashes when connected to dc to dc buck converter [closed]

So I used a common 230vAC to 12vDc (1AMP) wall adapter with dc jack like this and converted to 5v using a dc to dc buck converter same as based on lm2596s But the adapter LED starts blinking (...
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1answer
336 views

SMPS 5V without load, fluctuation on load TOP258PN [closed]

I am using PI Expert Online (this) to design a smps circuit for 5V, 2.5A output. I already have TOP258PN IC with me so built circuit for that. Change from schematics: I am not using choke and using ...
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4answers
527 views

Is DC-to-DC (24 V to 12 V) buck conversion typically more efficient than AC-to-DC (110 V to 12 V) conversion? [closed]

While building an online UPS system, I'm basing the choice to eliminate as many AC inverters from the system as possible because of the assumption that DC-to-DC conversion is more efficient than AC-to-...
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3answers
119 views

Please help me understand how to add AC power to my DC device

I have a device that runs off of three D batteries. I would like to be able to add a power cord so that I can plug it into the wall and run it off of that instead. I would also like to still be able ...
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1answer
226 views

Different Wattage Solar Panels for Home [different Voltage/Ampere]

My current solar system for home 12V 100W polycrystalline Solar Panel. 12V 75Ah Lead Acid solar tubular Battery. PWM 12V 10A Solar Charge Controller. 12V Input and 200VA Output Inverter. Current ...
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2answers
220 views

Power drop on AC-DC converter due to relay

A uController circuit is powered with an AC-DC converter. This circuit in turn acts on some relays to turn on and off some loads. We have two bi-stable relays and another simple relay (Omron G5DN-1A) ....
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4answers
195 views

300VDC to 24VDC voltage converter - Cheapest implementation

In an application, 100+, 100W 24V halogen lamps need to be individually controlled and run simultaneously. They stay on for a few seconds at a time and need to have very constant irradiation. ...
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2answers
66 views

How to insulate DC from earth noise while keeping it referenced to it

I have an AC/DC converter (220 to 24) inside an electrical cabinet. The 0VDC is referenced to earth, like this (couldn't find a symbol for an AC/DC converter in the schematic editor so I made a dirty ...
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2answers
118 views

AC “chopping” power supply inrush current problem

I've made a simple AC to DC chopping/switching power supply circuit (I'm not sure if it's called that) as shown below. in the left part of circuit (which is the gating/chopping part) when the ...
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2answers
82 views

3.3v Powersupply

I have been needing a 3.3 volt power supply that can use at least 12-24 volts ac dc in. I have looked online and managed to make this schematic but I have no idea if it works. I was hoping if you ...

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