Questions tagged [ac]

This tag refers to alternating current mains power. It usually applies to voltages with >100V RMS, but can also be used for ex. 24V industrial AC power.

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21
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5answers
27k views

Why can I put an electrolytic capacitor on AC?

I have seen here and there schematics with electrolytic capacitors put on AC. And this sounds weird to me. Electrolytic capacitors have a polarity, right? If we invert the polarities on DC, bad ...
-1
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0answers
38 views

Convert AC to different frequencies

How can we convert AC with a frequency of 5Hz to AC with a frequency of 10Hz.I considered using a transformer but the output signal of the transformer has the same frequency with the input signal. How ...
0
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1answer
53 views

Arduino freezes due to: power supply?

This is going to be a long question but I don't want to leave any loose ends. I'm developing an incubator which includes a hot air pump to conduct heated air through a hose to a closed chamber (~100 ...
0
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0answers
34 views

can I use neutral in an AC circuit as the negative conductor on a separate DC circuit

I have a particular application, but I also generally want to know the answer. I have an aluminium sail boat that has a extensive DC electrical system, as well as a 500watt inverter for a basic AC ...
0
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1answer
18 views

Correct AC input wiring for electronic door lock PSU

I have a small PSU that outputs 12v DC for use with electronic door locks, but I'm a bit uncertain about the AC input. From the diagram it looks like there is two AC live wires, and a single earth. ...
0
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2answers
45 views

Resonant frequency and maximum signal width

I've seen resonant frequency being defined as the point where the input signal is in phase with the output signal (So reactance/susceptance is 0). However conceptually, teaching material seems to link ...
1
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2answers
63 views

Soft starter for centrifugal pump

Do most manufactured centrifugal pumps come equipped with soft starters, and is it a good idea to invest in one if they're going to be frequently switched on/off?
0
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1answer
198 views

AC voltage measurement upto 230V AC

How can I effectively measure up to 230 v AC using a PIC micro controller? I just want to measure Line voltage, and as per the measurement I need to apply in the design.
2
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1answer
401 views

Does a universal motor run better on flat DC as opposed to pulsed DC?

After reading this: Is there any advantage in running a universal motor on DC power? I want to know, does it improve the motor characteristics if you supply the motor flat DC instead of pulsed (...
-3
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1answer
73 views

Maximum power transfer of transformer [closed]

We have this transformer: simulate this circuit – Schematic created using CircuitLab The power transfered to R1 resistor is maximized when the frequency of the signal is very big.This means ...
0
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1answer
121 views

How do you combine 2 AC power sources?

To combine 2 DC power sources, you can diode OR them both together. You can't just directly connect them together because their voltage outputs may differ ever-so-slightly, leading to imbalanced ...
0
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2answers
66 views

How do you determine the direction of AC current? (ex: whether your solar-powered house is drawing from the city power grid or adding to the grid)

I'd like to measure the voltage and current of mains AC power at the fuse box where a house is connected to the grid. Assuming the house has solar panels on it, sometimes it will draw from the grid, ...
1
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1answer
37 views

RC low pass filter difference with RC high pass filter

This is a low pass filter: simulate this circuit – Schematic created using CircuitLab This a high pass filter: simulate this circuit If we add a load resistor to the high pass filter it ...
0
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1answer
49 views

how to generate 70V AC from TLP222G-2

I have 70VDC 30mA source I need to control optoisolators to generate 70V AC signal I can use TLP222g-2 dual isolators. to build the h bridge I have a single PWM channel from my MCU. Is it possible to ...
3
votes
2answers
206 views

How does this old fan regulator circuit work?

I was on the lookout for an old fan regulator. I had heard that its power consumption was constant at all speeds. I could lay my hands on this 1970 regulator. It appears to be a transformer with ...
0
votes
1answer
35 views

Garage door openers - BLDC x AC monophasic - Is that possible?

As far as I know, electronic control boards for garage doors, they basically control two main types of motors: AC induction monophasic, one neutral and two phases, driven by TRIAC or relay. It takes ...
1
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2answers
44 views

Controlling AC motor with relay vs. switch on motor

Is there a difference in terms of operation between switching a relay connected to mains for an AC motor versus opening/closing a switch on the motor? Would the internal protection circuitry ...
0
votes
1answer
179 views

Ac current source(1-10mA) with help of 5V dc battery

I have been working on a project in which I have been using an Howland AC current source (it has an AC voltage source in it) as a current source. But as an upgrade, I need a current of same sort which ...
1
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1answer
482 views

acs71020 Connecting and reading voltage properly

I am using an ACS71020 3.3V I2C version hooked up to ESP32. I have connected the IC as proposed in the datasheet. Rsense used is 1.8k ohm as proposed in the evaluation board user manual for 230-240 ...
1
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1answer
110 views

What is this symbol on a schematic for an old milling machine?

On the schematic below, I'm having trouble identifying what the symbol drawn on top of motors 2 and 3 means. I've never seen anything like it. They're only present on the high-power spindle and feed ...
0
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1answer
32 views

Capacitive reactance related to frequency

Why does capacitive reactance decrease with the increase of the frequency of the applied signal? It is easy to prove why capacitive reactance decreases with increased capacitance. The more we increase ...
2
votes
1answer
156 views

Power amplifier simulation and real time experiment mismatch problem

Thanks in advance to anyone who will take the time to read my first post here. At present, I am doing a simulation of a power amplifier in LTSPice. The schematic and relevant files are uploaded in a ...
2
votes
3answers
13k views

Is it possible to convert 3 Phase 220V to 110V without use of a transformer?

I am living in an area where line voltage is 220V. If I have access to all 3 phases, is it possible to create a "socket" with output voltage of ~110V, without use of a transformer? This is primarily a ...
8
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4answers
3k views

Why skin effect happens at the center of a conductor?

I was reading an article about Skin Effect. I know what skin effect is, but I wanted to know what causes it. Why is the back EMF strongest at the center? Why is it not distributed uniformly at the ...
0
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1answer
45 views

Circuit giving values on both AC and DC

I have a generator stopper which works on 220 volt AC (in India 220 volt AC is normal supply) and has an electromagnet which pulls up a lever and the generator is stopped. It works perfectly when the ...
0
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1answer
135 views

Figuring out the AC equivalent circuit(re model) of a Pre-Amplifier and Tone Control Circuit

I need help figuring out the AC equivalent circuit of this preamplifier circuit. I'm quite familiar with all the simple BJT configurations but this is my first configuring such a relatively ...
0
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1answer
320 views

Increase the drive strength of the circuit

Hi I am trying to send a pulse over one circuit and recieve it at another. For reference I have replaced the circuit that revices the signal with a resistance connected to ground to act as the load. ...
3
votes
1answer
100 views

What is the advantage of kWh based tariff? [closed]

Electricity consumers are divided into domestic, commercial, industrial , etc based on the power factor. Domestic loads are mainly resistive. But not 100% resistive always. The industrial meters shows ...
0
votes
2answers
270 views

Voltage phase delay

Is there a method of delaying the phase of AC voltages? I ask because if I could somehow create a second identical and overlapping sine wave 1 half cycle ahead of the original AC waveform in a power ...
0
votes
0answers
31 views

Need an isolator or similar to fix my design issue

I have an arrangement where 0-80 VDC signal is provided as input to a measurement board for measuring this DC signal. But somehow along with this 80 VDC signal, there is noise coming in the circuit ...
1
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1answer
41 views

Power output only when mains power cut and only bu ups

I have a ups in my home.I want to install a fan in my room which run only when the mains power supply is cut and ups is supplying the power.How can I do this.
2
votes
3answers
91 views

Measuring the waveform of mains voltage using an oscilloscope

I understand this is a recurring discussion, but I still can't find a concrete answer to this question. I would like to know how can I inspect the waveform of my UPS output (230V) using an ...
2
votes
1answer
47 views

Laplace tranfsorm of capacitor functions and initial conditions

I may be asking something trivial, but unfortunately, I could not find an answer so far. Suppose an AC circuit. The voltage of the capacitor is given by $$v_C(t)=Q(t)/C = 1/C [ \int_0^t i_C(τ)dτ + v_C(...
1
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1answer
2k views

Use ACS712 current sensor in two-phase electrical system

I'm thinking about using the Allegro ACS712 current sensor for measuring house equipment current consumption (for example TV). The issue I'm facing is that my house energy supply is built around two ...
0
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3answers
181 views

What is reactive energy?

We know the typical equation for instantaneous power (which can be proven): \$p(t)=v(t)i(t)\$. In sinusoidal steady state (let's ignore harmonics for simplicity), \$v(t)=\sqrt{2} V_{\text{rms}} \cos{(\...
1
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1answer
239 views

Nest Protect gen 2 battery to POE

Hey all i am looking for some advice in how to go about my project with a Nest Protect gen 2. In my home i have ran cat6 wire to all 3 locations that require a smoke detector. These cat6 cables are ...
0
votes
1answer
414 views

How can I measure AC magnetic field using linear hall effect sensor with the arduino?

I have a SS49E hall effect sensor. I want to measure magnetic field in gauss using arduino analog output. I have a code for analog application but is this appropriate just for the dc magnetic field ...
0
votes
2answers
181 views

Current draw on the AC input of a PSU

I have a cheap PSU of this sort, used for my 3d printer. It has a 110V input, and a 12V output with 20A maximum current. Unfortunately, it doesn't have detailed specs/data available beyond that. Now, ...
0
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2answers
57 views

Vacuum Fluorescent Display: What are the benefits of an AC filament driver instead of DC?

Question is already in the title: What is/are the benefit(s) of an AC filament driver instead of DC for VFD displays? It works with DC so why to invest in an AC driver? Anyone?
0
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1answer
31 views

Resistive AC voltage divider and phase

I built myself a power monitor a few years ago that works and I was trying to simplify mine by cutting out an expensive and hard to find 12V ac:ac adapter. I am familiar with a voltage divider and it'...
19
votes
6answers
13k views

What are the highest DC and AC voltages or currents that can be considered as safe?

By safe I mean safe for us when we touch a wire that is not insulated. I have heard that human body resistance is normally 50k Ohm when dry and 20K Ohm when wet. Therefore, these voltages or currents ...
1
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1answer
228 views

EL wire + inverter questions

I have a question on connecting 3V EL wires to a 12V unit inverter. I know that is not okay to do so in a DC circuit, but I don't know if it is okay to connect them in an AC circuit. Here is the link ...
3
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3answers
62 views

Considerations for converting a LED Bulb from AC to DC power

I was asked by my uncle to convert 22 units of gx53 LED Bulbs that are powered by 230VAC 5W to DC voltage power. The LED Bulb itself consists of 5 LEDs(string) in series, in parallel to another 5 LEDs(...
1
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3answers
80 views

Why can't the earth discharge my DC batteries?

Electrical newbie here. After watching this video I noticed that in the event of a fault, the AC power in your house can discharge into the earth/ground (which thus causes the house breaker to trip). ...
0
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1answer
58 views

What is the actual direction of real current in an A.C. generator? From the North pole to the South?

I see diagrams of a current being generated in a loop or square-ish section of wire that is rotating between two magnetic poles... a north on one side and a south on the other... BUT, the current ...
2
votes
2answers
243 views

How does a RC Lowpass filter work?

So I've been trying to understand how an RC lowpass filter works, and I think I got it, but I just need some clarification. My understanding: So an RC Lowpass filter in a nutshell is just a voltage ...
0
votes
1answer
89 views

Adding additional protections to a PSU (Meanwell IRM-01-5)

Since I am new here, first I would like to apologize if I did draw this schematic wrong (i.e. lines do cross, etc.). It is a few days that I am using this online editor, so I am still in the learning ...
0
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3answers
655 views

Can I safely substitute a DC converter for the Macbook's AC adapter?

I want to go from this: to this: The converter would be this: http://smile.amazon.com/dp/B00HVCWGNE or something like it. Does this sound safe? The step up converter would be set to a specific ...
0
votes
1answer
316 views

AC signal to a coaxial cable

I am quite new in this field and I started recently by reading the first books in electrical engineering where I learned the concept of current, voltage, impedance, reactance (inductive and capacitive)...
0
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1answer
737 views

Allegro ACS71020 problem interpreting I2C data

I've added an Allegro ACS71020 to my Arduino project to measure power usage (circuit shown below). I can connect to I2C on 0x63 and I get response (check the image below) - but the values do not ...

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