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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Is it possible to replace the electrolytic capacitor in a full wave rectifier bridge with a ceramic capacitor?

Why do we use electrolytic capacitors in full wave rectifier bridges? Is it because we can have huge capacitance with electrolytic type or is it because the output is DC voltage where polarity is a ...
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UCC3895DW FOR PSFB?

I am designing a 3KW CC/CV (60V 50AMP max) power supply and I choose UCC28951 PSFB controller but this part is out of stock and I can't get it so my question is can I design a 3KW power supply on ...
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48 views

Looking for an AC - DC power supply. Help on specs [closed]

I have been using my old auto stereo amplifier in my home and picked up a meanwell adjustable 0-48V DC. I would like to use a larger amplifier now and would like recommendations for the new supply. ...
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21 views

Please help me understand the equipment and setup needed to power a 4*100Ah battery system via Generator + Shore power [closed]

I am planning a build for a campervan. I have a loose understanding of how to achieve what I want, but I'd like to ask some questions to people who are competent in this realm. I am going to use 4*...
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-1 votes
1 answer
66 views

Why do AC/DC power supplies need cooling while transformers operating at similar power levels don't?

I will be running a 110 volt to 6.3 volt transformer that delivers 65 watts. I usually see these types of transformers in home appliances and guitar amplifiers with no active cooling. Why do these ...
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2 votes
3 answers
81 views

How to power two ESP-01S chips from 220 V AC [closed]

I would like to supply power for two ESP-01S microcontroller chips. I am a beginner with such kind of circuits. There are some constraints: The only available power source is 220 V AC, so I need an ...
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  • 626
1 vote
3 answers
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Using 2 AC-DC adapters in parallel with block diodes to safely increase current capacity

The way I understand it, if doubling up 2 AC-DC adapters one might output a slightly higher voltage than the other, and only a very slight voltage imbalance could lead to a larger current imbalance, ...
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-2 votes
0 answers
72 views

Getting AC output from purported DC-DC boost converter. What gives?

Hey gang got a "thing" here that has me confused. Briefly, I'm working on a project that needs +5VDC to power a load, but also needs -5VDC at one point in the circuit, to send to the Gate of ...
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39 views

Creating a line level signal and DC power from a speaker level signal

I have a speaker connected to an amplifier with some wires that run through a wall. I may want to replace the regular speaker with one that has an integrated amp and takes a line level audio input and ...
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18 votes
3 answers
4k views

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 ...
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3 answers
170 views

Long term issues with AC/DC converter in always ON application

We have designed an "always ON" electronic home automation device which goes behind the switchboard (inside the wall.) This is the first commercial product that I am designing, so bear with ...
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CCM boost PFC rms current ca;cu;ation

Does anyone know how to calculate the Boost PFC rms current. I read the "Fundamentals of Power Electronics", there is a formula but I can't total understand. 1.) How to get the red part ...
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  • 409
3 votes
4 answers
521 views

Problem with building -12/12 V power supply and AC/AC converter

At the beginning I wanted to point out that I don't know much about electronics and I'm just starting my adventure with it. I recently bought an AC/AC 12 V power supply and to my surprise, it showed ...
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Small vs large inverter efficiencies

I want to run a 60W device 24/7 through an inverter as efficiently as possible. I see that inverters become very inefficient at low loads relative to their capacity. Is this only because of factoring ...
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1 vote
3 answers
105 views

AC/DC transformer and isolation

My theoretical knowledge from engineering school is a little bit rusty, and I am not working in this field so I have not been practicing in a long time. But I asked myself a question that I can't ...
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48 views

40-96 VAC to DC conversion

I am trying to build a simple voltage meter. One that displays the AC voltage onto a small LED display run from an Arduino Micro. I have the nuts and bolts down but I'd like to be able to power the ...
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10 votes
5 answers
251 views

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 ...
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1 vote
0 answers
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How does this circuit convert AC to DC? [duplicate]

I'm trying to understand this circuit taken from a rechargeable flashlight. There's a 4V sealed lead-acid battery (not shown in the images) that gets charged when you connect the flashlight to 230V AC....
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1 vote
3 answers
65 views

Nominal or real AC/DC power supply values

I have three older AC/DC power supplies with these nominal values: Input 120 Vac, 0.3 A, 60 Hz Output 16 Vdc, 900 mA Input 120 Vac, ?, 60 Hz Output 16 Vdc, 1 A Input 120 Vac, 60 Hz, 4 W Output 9 Vdc, ...
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4 votes
6 answers
542 views

Is full wave rectified AC, without a smoothing capacitor, okay for switching a DC solenoid and a DC relay?

I have a circuit where the 24V AC secondary voltage of a transformer is full wave rectified to DC. The only parts that this circuit is connected are some 24VDC solenoids and a 24VDC relay. The ...
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  • 381
1 vote
2 answers
69 views

Step-down conversion materials

I have an ac adapter on which I would like to reduce the output, from 24 vdc to let's say 6 vdc. What type of diodes should I use and how many? What about heat dissipation?
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3 answers
99 views

Confused in readings of oscilloscope

I have this reading of a oscilloscope for a half wave rectifier: Pk-Pk voltage is 17.6V. The channel is set to 5V division. I asked my dad who is a electric engineer and he told me that Vp = 17.6/2 = ...
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-1 votes
3 answers
91 views

Simple circuit to sample 120 VAC and yield 8.33 ms pulses

Have you noticed the lack of availability and prices of RTC chips lately? A simple DS1307 RTC is simply not available right now. Last year I purchased DS1307s for less than a buck. Now they are $4+ ...
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0 answers
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How to create a step-down ac transformer without primary coil?

I am currently trying to build a coil gun for a school project in an engineering program and am facing certain resource constraints put on me by the professor. I have looked at many different coil gun ...
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0 votes
1 answer
79 views

Can I mix three wires that carry single phase 240V AC and four wires that carry USB signals into a signal custom cable?

I am planning to design a system that requires AC power supply as well as a USB connection. I found a connector that has provision for the same here. If I were to pass 240 VAC single phase along with ...
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0 votes
0 answers
37 views

Connecting a rectified and smoothen DC to an inverter

I'm preparing to build an axial flux generator and my plan is to generate 24v from the generator, rectify it, smoothen it with a super capacitor and then connect it to a 24v inverter. I want to avoid ...
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2 answers
55 views

How do I calculate current when using a power supply?

Edit: I’ve just learned that a 500mA PSU is not going to necessarily output 500mA; it’s not a constant current PSU. It CAN output that much, but only if its components are asking for that much. It ...
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0 votes
0 answers
123 views

How to mathematically choose values for a pi filter without knowing the cutoff frequency?

I am trying to design an AC to DC converter. After the rectifier, I have a pi filter. I need to calculate my L and C values, but I don't know what the cutoff frequency is/how to find it! Any help is ...
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1 vote
1 answer
34 views

Join two battery operated LED light strings

I have two 2 meter LED lights strings (lights are in plastic flower) that I would like to power using AC to DC universal adapter. Currently the LED lights are powered by 2 AA Batteries with a switch ...
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0 votes
2 answers
217 views

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

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: Note: The question is not opinion-based, since the existing answers ...
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1 vote
2 answers
151 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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1 vote
1 answer
99 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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  • 2,041
1 vote
2 answers
103 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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0 votes
0 answers
37 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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0 votes
1 answer
55 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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  • 109
0 votes
3 answers
94 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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-1 votes
2 answers
77 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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  • 155
0 votes
1 answer
235 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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0 votes
2 answers
62 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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  • 103
2 votes
1 answer
432 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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0 votes
0 answers
60 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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-1 votes
1 answer
62 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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1 vote
3 answers
162 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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1 vote
1 answer
56 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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0 votes
1 answer
78 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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0 votes
2 answers
291 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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  • 103
0 votes
3 answers
168 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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  • 235
0 votes
1 answer
145 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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0 votes
2 answers
119 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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0 votes
1 answer
69 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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