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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127 views

When to use X1 or X2 capacitor?

I've a simple circuit where I need to detect AC voltage presence via a microcontroller (ESP32). The ESP32 is a 3.3V device, and requires (worst case) 2.8V to consider a logical one on a GPIO. I'm ...
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164 views

What do apparent power, real power, instantaneous power and reactive power all mean in AC circuits? [duplicate]

We've just started AC circuit analysis in class, and the terms that I mentioned above popped up all at once. I'm new to the idea of phasors(I usually visualize them as arrows making a certain angle ...
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66 views

How to wire a single wire alternator to a bridge rectifier?

I'm trying to make a 25cc weed eater generator (for fun) and I'm thinking of using an alternator to take the rotary output from the engine and turn it into electricity. I need a way to take the 12-14V ...
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69 views

Magnetic field saturation in ac circuit

We have an AC voltage source connected to an ideal inductor that has no resistance.The inductor is wound around a ferromagnetic material. The maximum value of the driving voltage source is big enough ...
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2answers
80 views

How can I find i1 and i2 in function of Vg in this circuit?

Given the attached schema I'd love to find the analytical temporal and frequency expressions for the current in the 2 branches: i1 and i2. R0, R1, R2, C1, C2 and Vg(t) are given. In the time domain ...
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51 views

Class A amplifier

So i have to make a circuit for my university, and it has to be made in electronics workbench. I tried to make a class A amp after this schematic: And made this in EWB: My problem is that my circuit ...
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1answer
35 views

Delta wye transformer, voltages explanation?

So I'm doing a delta wye transformer simulation in simulink, and I need some clarification about transformer voltages. Here's a image from a youtube video We have phase voltages on primary that ...
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56 views

Power drill motor with no electronics? [duplicate]

I have a Bosch power drill, the same as in this other question. I checked it carefully and it doesn't seem to have a capacitor or any other electronic components. Does it mean the universal motor ...
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1answer
66 views

Finding the magnitude of the Transfer Function

This is the circuit, where some of the components values where given and the others, I found myself. (Sorry I have no link to the design, I needed membership there) The following part says to draw ...
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1answer
145 views

Isolated mains (AC) presence detector

I need to detect a AC mains outage, isolated way. Output marked as [?] goes to AVR MCU. I don't need to detect undervoltage or zero-crossings. I actually need a simple feedback to MCU interrupt which ...
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4answers
2k views

Half wave vs full wave rectifier [duplicate]

I know that a rectifier converts AC voltage into pulsating DC voltage. However, when would you use a half wave rectifier as opposed to a full wave rectifier ? Can you give an example of some ...
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2answers
230 views

How to show that voltages on diagram are 120° apart?

So i'm doing a matlab simulation of delta wye transformer and would need to show the phase shift between voltages. Here is a picture of input voltages so how would I show on this graph mathematically ...
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1answer
65 views

AC line isolation on multi-level PCB design

Due to space limit I had to design the PCB in multi-level form, the top front side of the PCB is AC line and under that is DC capacitors: Is the 3mm air gap between AC line and DC capacitors enough ...
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108 views

Importance of the apparent power

It is said that, though only active power can actually do work, we have to consider apparent power to dimension the source. But what would seem important to me for that would be to know the maximum ...
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69 views

Draw the corresponding AC circuit

I have the following transistor, whose I have calculated the parameters that were not given. Now, I want to draw the corresponding AC circuit. Can someone help me with this or give me any source ...
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1answer
75 views

Help regarding Ac current limiting using resistor

I've 12v(Vrms) 1A AC transformer. I need to regulate it to 1to 4ma maximum output without having much voltage drop. Output load is an animal skin which has resistance in it. Can I just use a ...
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39 views

Pulsing one-way current

In EveryCircuit, they have three different voltage sources, one is DC (left), one is AC (middle), and then one is just pulsing (right) -- Is there a formal name for the 'pulsing one-way-current'? Is ...
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2answers
87 views

Can transformers be used to adjust capacitors?

It seems capacitors are subject to a "quality triangle", where we can only pick two out of three desirable traits: High voltage rating High capacitance Cheap For example, a high-voltage high-...
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2answers
117 views

How to safely interface 220VAC in a PCB

I am making a PCB circuit that detects the state of a mains voltage switch. Now since I am dealing with mains voltage a lot can go wrong and a lot can go wrong badly so I would like to ask for some ...
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1answer
93 views

Amplify AC signal only

I amplify a signal which including AC and DC.Why is the output waveform changed when C1 is 0.1u?And how to decide the value of C1?
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2answers
52 views

How to bias an AC signal correctly?

I have an AC signal and want to give it a new DC offset. There are some questions about my experiment results. (The original signal bias and terminal output bias are the same because I want to know ...
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2answers
57 views

Finding 70% Voltage Point

Let \$v_1\$ be the input AC voltage and \$v_2\$ be the output AC voltage such that gain \$\dfrac{v_2}{v_1} = \dfrac{A+jB}{D+jE}\$ where \$j = \sqrt{-1}\$. How should I find the 70% point (the point ...
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33 views

In search for more Exercises

I'm currently studying in Germany for Electrical Engineering (course in English). Due to incoming exam, I am looking for more exercise material as although my course is in English, the school library ...
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2answers
75 views

How is the ac load line for the following amplifier derived?

So I am trying to derive the ac load line for the following class A power amplifier First I considered the reflected load/equivalent resistance of the transformer, this becomes $$R'_{L} = (\frac{n_{...
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50 views

AC Motor voltage

I have a 3 phased AC electrical motor, without any plate on it, so I don't know which voltage should be provided to the motor either 220 or 440V. Is there any way that I can find out?
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1answer
56 views

hall current sensor potential failure mode

I was curious what are potential common failure modes for hall-based ac current sensors in a mains ac environment? Specifically those like the acs712 and acs723. Assume you have a 5amp current sensor, ...
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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 ...
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2answers
153 views

Calculation for the distance between maximum swings in the drift distance of electrons

I am currently studying the textbook Practical Electronics for Inventors, Fourth Edition, by Scherz and Monk. In section 2.4.1 Applying a Voltage, the authors have written the following: In the case ...
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68 views

Find capacitor in AC RLC circuit, so that power dissipated in resistor is maximum

I didn't find a topic on my question, that's why I'm creating one (but if there is one, don't hesitate to tell me). I am stuck on an exercise with AC circuits (RLC): The exercise tells me that I have ...
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2answers
57 views

Induction from AC or RMF

I'm struggling to get my head around induction motors. Specifically, from what I can see the rotating magnetic field created by the 3 phases creates flux lines which sweep across the rotor bars which ...
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4answers
566 views

Why shouldn't two AC sources be connected in parallel?

In data centers, servers usually have redundant power supplies, which makes it possible to plug them to two different UPS units. This way, the server continues to function correctly if one of the PSU ...
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1answer
40 views

Energy dissipation of a resistor in an AC circuit

I am given a resistor of known resistance with a sinusoidal voltage across it, and am asked to calculate the energy dissipation between t=0 and t=1. Not sure how to do it. Would I Use P=V^2/R and ...
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30 views

SSR selection for dc controlling ac

Hi I am trying to create a circuit that turns on automatically when a multi pin pannel plug is connected (specifically a Weipu connector). The idea is that the 3.3V dc voltage is used to control an ...
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40 views

Oscillator in Multisim [duplicate]

newbie here. As I read through webpages, i got to know that Oscillators are capable of changing DC to AC. I made a phase shift circuit in Multisim, but I got no idea what should I do next. I was ...
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3answers
124 views

How do electricians calculate the maximum allowed on circuit breakers if the current is measured in AC?

Correct me if I’m wrong but the majority of electronics circuit operate of a 3V3 constant DC voltage, which the current would be reasonably stable draw apart from charging up capacitors, chips loading ...
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1answer
143 views

DDS238 AC Power Meter: how to calculate current power consumption using pulses

I have a DDS238 AC power meter with 2000 pulses/KWh (1p/0.5Wh) and I want to calculate the real-time power consumption and play an alarm if the value exceed a specific value. I'm using an ESP8266 by ...
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1answer
28 views

High Impedance Load Driving with Mosfet as Common Source Configuration

I am just trying a design ac switch with mosfets which are connected as common source. Mosfets will drive 16.2A load in normal conditions. When I try to drive 10 ohm load with 162V (peak, 400hz), as ...
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1answer
39 views

Question: AC Voltage and Current variables

So I know how alternating current is produced, but I'm curious to what determines the voltage and amount of current moving within the wire. Does the frequency of the alternations give more voltage/...
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48 views

Triac Switching Circuit

I will switch an ac load with a triac. I am providing a dc voltage of 5V on the gate of first Triac and 0V on the gate of second Triac. In the first picture the triac is working and the switch is ...
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2answers
2k views

Do multimedia speaker systems run on AC power rather than DC?

I am talking about the typical multimedia speakers that are generally connected to the computer’s audio line-out point. For example, my power adapter for Altec Lansing multimedia speakers says Input ...
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1answer
97 views

How do fireplace direct ignition control modules work?

My gas fireplace has an electric spark ignition that isn't sparking. I'd like to 'test' it, but I'm not sure what a working one would be doing. The spark contact has 120VAC with 4A current when I ...
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1answer
63 views

Four-phase power from one-phase?

I have four AC electromagnets that I want to drive 90 degrees out of phase with each other. I want this device to work on regular wall-socket power. I could drive two electromagnets 180 degrees out of ...
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1answer
131 views

What happens to the Real and Reactive power when I increase the excitation current in a 3-Phase Synchronous Generator?

Basically my doubt is, for the same load, why does the Real power remain constant when I increase the excitation current?
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30 views

Primary coil of an ideal transformer [duplicate]

My textbook says that when primary winding of an ideal transformer is connected to an alternating voltage, an alternating current flows which in turn produces an alternating flux which causes an EMF ...
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2answers
251 views

Type of capacitor to bridge X10 signals in household power

X10 is a protocol for communication among electronic devices used for home automation where the signals involve brief radio frequency (RF) bursts over a home's A/C power lines. Household wiring often ...
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1answer
63 views

AC line detection, with or without optocoupler?

If you want just to detect AC line (220VAC) existence using micro-controller, does using optocoupler has any advantages rather to simple RC circuit? Even if you want to meet EMC/EMI/Industrial ...
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1answer
63 views

How to get started with AVR Microcontrollers? [closed]

I have an AVR ATMega32A Microcontroller, a Programmer that supports my microcontroller, a breadboard and some electronic stuff ...
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1answer
81 views

Microwave rotating plate

I noticed that the rotating plate of many microwave ovens usually rotates with a specific direction, even if sometimes this changes. What makes the plate rotating clockwise/counterclockwise? I know ...
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37 views

How to find current and voltage of a certain appliance connected to an outlet?

Objective: I'm new to electricity and trying to convert my mirror integrated with LED work with a power bank. I need to find how much voltage and current is needed to make it work. How can I measure ...
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0answers
56 views

How to solve for V0 in the next circuit

How can I solve for V0 on the next circuit if Z1 = 1, Z2 = j, Z3 = -j. All the ways I'v tried, V0 depends ends depending on V0, maybe using superposition theorem? Attempt 1: ( Calculating current ...

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