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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45 views

In AC/DC adapters, why can't the DC cable be detached from the adapter?

I notice that in most (all?) AC/DC adapters, the DC cable can't be detached from the adapter. Is there a reason for that? Example:
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46 views

Non-isolated SMPS [closed]

I am designing a non-isolated SMPS for LED drive application. Total output power is 10 W. There's a intermittent failures of inrush current limit resistor and 60 V is measured between product case and ...
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2answers
121 views

Do all AC-DC converters produce current spikes in input?

I am designing a simple rectifier circuit with LTSpice (I am planning to build one for myself) and I found out that AC-DC converters require PFC circuits to prevent huge input spikes (?). I tried ...
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1answer
50 views

How do I calculate the number of turns or inductance while designing a transformer?

I was trying to design a transformer for a SMPS but can’t find any resource to calculate the number of turns and the core area. I know that the turns ratio has dependency with the signal frequency. If ...
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2answers
99 views

Electrical light switches for 12 V DC

I am converting a campervan at the moment and am now at the stage of choosing the light switches to use with my 12 V lights. I am not keen on the ones for caravans as they are not that great to look ...
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27 views

Step down 5V Power supply for IoT

I am trying to create common DC power supply to support ESP32 Development board, Servo Moter (MG995) & Fan Motor (0.2A), all required 5V DC. I am considering Hi-Link 5V 4A SMPS Mini PCB Mounted ...
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1answer
46 views

Higher voltages between protective earth ground (mains) and function generator than expected

I uploaded a video to YouTube specifically to help me explain my question. Please watch it if you can. Otherwise, here is my text-based description: I have an oscilloscope, function generator and ...
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3answers
85 views

Connect rectifier to DC power source? [closed]

I'm thinking about DC appliances and energy efficiency. A common appliance like an air conditioner has a rectifier to convert 230V AC into 50V DC. If I connect the appliance directly to 50V DC instead ...
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2answers
70 views

Will transformer work with lower voltage? [closed]

I'm looking for a way to convert 8VAC to direct current. I found a converter that can convert 10V~20V to 12V3A. Will the converter work when I input it with 8V? And how much output voltage will be ...
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1answer
109 views

AC to DC converter that outputs positive and negative voltage [closed]

I have to design a power supply that takes AC, converts to DC and outputs 9V and -9V with respect to ground. The current being handled is no greater than 100mA (Possibly much smaller than 100mA). The ...
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2answers
56 views

Why would a 32VDC fuse only work with 22VAC?

I am trying to find a 6-port version of this: https://czh-labs.com/products/czh-labs-din-rail-mount-ac-dc-532v-10-position-power-distribution-fuse-module-board-p0445 I found something close (https://...
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1answer
88 views

Powering a DC Motor Controller + DC Motor with AC Power Supply

TL;DR: My system needs DC power input--maximum of 250W @ 24V--but with the use of an A/C power source. How do I go about this? I have no idea where to even acquire a DC power supply, but I'm not sure ...
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55 views

Why is there earthing (the neon bulb on the tester glows faintly) on Hi-Link PM01's output or another AC-DC wall adapter?

I have a 5V relay circuit to power from AC using Hi-Link 5v/3w PM-01 module, however when i tested with a tester (neon bulb type) there is indication of earthing (neon blub glows brightly) I have ...
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1answer
60 views

Need an AC to DC converter and have two input options (16 VAC or 120 VAC). What are tradeoffs using a lower AC voltage vs the higher one?

I'm starting a project to replace an incandescent lit house number sign with one lit by an LED strip. I'm using existing wires and plan to do AC to DC conversion in the basement (3.3 VDC or 24 VDC--...
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3answers
103 views

AC to DC converter/rectifier huge input current spike

A simple rectifier circuit results in huge AC input current surge. As I understand it, it is because of the capacitor on the output. How is this problem solved? A resistor on the capacitor? A current ...
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1answer
45 views

Half wave rectified average output power

In the highlighted portion for the AVERAGE power, why did he use the DC RMS output voltage and not the DC AVERAGE output voltage? Do we ever use the DC AVERAGE output voltage for finding power? ...
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1answer
58 views

Design considerations for 3-phase AC-DC converter 60 vs 400 Hz

If I want to convert 400 Hz, three-phase, 200 VL-L to 28 VDC, how would I go about doing that compared to a conventional 60 Hz equivalent. In other words, what design considerations need to be taken ...
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2answers
119 views

How to know if my AC/DC adapter 12V-5A is enough for 3 stepper motors of 3A each?

I am more in mechanics then in electrical engineering so sorry if this question sounds silly for you. I have a little CNC machine with NEMA 17 stepper motors but their power is not enough for me, so I ...
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3answers
164 views

Can I safely turn a standard computer PSU into a 220VAC to 36VDC converter?

I'm a mostly electronics noob, and wanting to be safe. I am wanting to build my own fog machine, using some piezoelectric discs that I believe work best with 36v (I'm guessing this from looking at ...
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1answer
95 views

Can I use a laptop charger as a psu for a guitar amp?

My amp is a Blackstar core id 40 and has info in the back that says "Use 16V/3.5A DC Power Supply". I'm confused on this part though if it refers to dc being the input or a dc adapter. Found ...
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2answers
85 views

24V Bridge Rectified Relay Circuit blowing L7805 & PIC18F

I've got a circuit which is powered using a 24VAC transformer fed into a KBU606G full bridge rectifier to generate 24VDC. Originally there was a 470uF smoothing capacitor, however I was unaware that ...
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1answer
65 views

Can I combine batteries and a transformer to power a device at same time? [duplicate]

Particularly i want to buy this smart lock tuya X2 (dont know if exactly the same of the link, just for reference) link and a I want to get the more possible rid of the preoccupation of getting ...
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0answers
32 views

I wnat to design a circuit with a DC load but need help calculating the required circuit breaker, cable etc on the AC side of the power supply

I need to design a circuit with a knowing DC load of 24Vdc 20 watts. Now I have a Puls PIC 120.241D power supply that I can use. My question is I need to spec the protective device on the incoming ac ...
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1answer
59 views

AC to DC power calculations? [closed]

I have an ac to dc power supply and it measures at 244.0Vac on the primary side and the secondary side it is reading 21.34Vdc. I attached a load to the secondary side that is drawing 0.390amps and ...
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4answers
119 views

How do I (safely) arrange power for circuit from AC

I'm a CompE guy, so there's a lot about the power side of my field that I'm a little unsure about. I've been working on a project involving an MSP430 microcontroller and I'm at the stage in ...
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3answers
810 views

How can low voltage, low-current power be efficiently extracted from mains?

If I wanted to drive, say, a 1V 0.1A device from mains, I could step down the voltage with a transformer, but if the device was basically just a resistor (overall), then the resistor would have to be ...
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1answer
98 views

12VDC from two different 230Vac voltage sources

I want 12VDC from two different AC source such as Main and DG supply. At a time only one source will be present. Right now I am using the circuit as shown below. Is there a way to replace two ...
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0answers
25 views

LT Spice simulation error: 'Time step too small'

Could someone get this up and running? Tried all the possibilities but it does not seem to work still. Here I am just trying to simulate the linked circuit here .. PMP7763 design reference
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0answers
33 views

Does active power factor correction help with internal radiated/conducted noise?

I am choosing parts for the supply of a device. The case will be a metal chassis and there will be an AC-DC (12 V) converter module inside mounted on the chassis. The total AC power draw will be less ...
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4answers
208 views

Limits to use an off-the-shelf grounded AC-DC power supply with a two-prong cable

We are selling a product using an AC-DC power supply manufactured by CUI INC (SDI24-5-U-P5 datasheet). We sold the product in a few European countries but we are currently talking with a new ...
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0answers
51 views

Flyback power supply - 132 kHz radiated magnetic field issue

I request your expertise on a radiated magnetic field around 132 kHz (low frequency) on a Flyback power supply. I'm using the LNK3694 driver with a switching frequency around 66 kHz. Using a circular ...
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3answers
529 views

Want to make a Chia farm of 156 external hard drives [closed]

I have two questions: How do I not burn down my house Is there any way I can use less electrical outlets by getting AC/DC splitters? Question 1: So basically I got 156 external hard drives. The AC ...
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4answers
514 views

What is the Zener diode doing in this 123V supply?

We are fixing up an old Atari game cabinet, and we keep blowing the Zener diode D802. This is a 51V zener diode, but we don't understand what it's doing and so we ...
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0answers
20 views

AC Leak or normal? [duplicate]

I have a strange situation in my house. From AC 230V I have an AC-DC 24V transformer which goes into a LAN Router with metal case. When I measure with a multimeter in AC Voltage between the case and ...
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0answers
35 views

Can I get power from my Thermostat's AC relay wires?

I have a 2-wire thermostat that activates my baseboard heater when the 2 wires are shorted. I did an experiment closing those two wires with a relay and got that working well with an ESP32 as the ...
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1answer
48 views

AC to DC signal to drive a MOSFET

I need to intercept a 220V AC line to drive a 3.3v MOSFET that activates (for example) an LED. Looking around, a solution could be to use an AC/DC converter but they are meant for powering (so mostly ...
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1answer
49 views

half controlable AC-DC converter

We are studying power electronics, AC-DC converters. Our teacher drawn a circuit with its graph like below: Id: inductor or load current. Vs: voltage of source. Vd: voltage of load or inductor. Iq: ...
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2answers
158 views

strong capacitive coupling of mains to isolated output of AC/DC converter?

I am using a RS-15-5 PSU from Meanwell for a test: datasheet here I built the following circuit: The left side (V1) is the mains side. The right side (V2, C3, L1, C2, R2) is the isolated DC side. As ...
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3answers
172 views

Power supply transformer question, double primary

I'm trying to make a circuit to look like this one: This is from ATM90E26 Application note, this IC needs to be connected to mains in order to measure voltage (220VAC) and current. I tried to look ...
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2answers
122 views

How to smooth fluctuating DC from transformer?

For an audio amplifier, I designed an AC to DC (220v to 12V 2A) power circuit like this: simulate this circuit – Schematic created using CircuitLab When I powered my amplifier with the circuit ...
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0answers
43 views

How do I rotate A2212 2200Kv BLDC via 220 V Ac?

I use Lipo battery (11.1V 25 C 3s) to rotate the motor. But now I want to rotate motor via 220V AC (Home supply).I followed this tutorial and successfully converted 220V AC to 12 V DC. But I am not ...
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1answer
74 views

Transforming bike dynamo output to reduce diode bridge loss ratio

I'd like to use a standard 6v/3w bike bottle dynamo to power a 18650 battery charging module TP4056 which also powers some LED's. Diode bridge rectifier steals 1.4v from the generator. In addition to ...
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3answers
95 views

Small AC-DC conversion/amplification

So essentially looking for the most efficient and effective way to take a 3V 50hz AC signal and convert it to an 11-33V DC signal (any voltage between 11 and 33 works for an input to embedded pc) . I ...
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2answers
190 views

Constant Current LED Driver using LM358

I have been working on a project for ACDC Constant LED driver with 1.2A, 36V specifications. While going through the internet, I found one of the circuit and couldn't understand the working the of the ...
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3answers
117 views

How can I reuse an AC speaker amplifier board with DC?

I'm planning to reuse this board powering it with a computer 12V DC power supply. It gets 9V AC 200mA from its own 220V AC transformer. I have basic understanding of electronics, so I've been ...
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1answer
50 views

12V AC to 12V DC converter to power an Arduino and some WS2812B 5050 LEDs

I am looking to convert 12V AC to 12V DC to power an Arduino through the VIN pin. The Arduino will be mounted on a PCB through header pins, please see below. This is the board I have at the moment. I ...
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0answers
53 views

Smallest Capacitor for Flyback AC/DC Converter

Most of the isolated flyback AC/DC converters I’ve seen place a rather large (>1uF) electrolytic capacitor in parallel with the bridge rectifier that follows the AC voltage source. To provide a ...
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1answer
68 views

How to protect low-voltage hardwired device against 120 V AC miswiring ? (I need a resettable solution)

I need to protect a hardwired device, made for AC low-voltage transformers (e.g. doorbell), from miswiring to a 120 V AC power line. It actually occurs no matter how many warnings I put everywhere. ...
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1answer
45 views

Inverter resistance and calculation confusion

I'm using a 1200W pure sine wave inverter and a series of extension cords to power devices in a mobile home. When charging my laptop, I noticed it was charging slowly. According to my battery ...
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2answers
108 views

AC-to-DC Conversion: Which topology is better?

I am putting together a circuit board that is supposed to do its own power regulation. I need to convert 120VAC to ~5VDC. Due to the very limited real estate on the PCB, I would rather not use ...

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