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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1answer
32 views

IGBT gate driver burned, why?

I am trying to use an IGBT module (dual IGBTs in common-emitter arrangement) as a static switch for 120VAC. I've done as much reading as I can, and I understand there are issues with losses and turn-...
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25 views

What is the best transistor model for bjt transistor ac analysis(middle response)?

Nowadays I am working on bjt transistor ac analysis. I use r(e) model for bjt transistors ac analysis in my university. I know there are separate methods for low frequency medium frequency high ...
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2answers
32 views

AC phase current sensing using Isolated delta-sigma modulator

I am trying to design a isolated AC current sensor. I've chosen the AMC1106 Isolated Delta-Sigma Modulator. (change my mind if you think there is a better solution for 220V AC; 2A Max; 0.25%) The ...
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4answers
57 views

Effect on phase angle due to resistance

When an ac voltage source is applied to a resistor, current and voltage are in phase in the circuit. When an ac voltage is applied to a pure inductor, voltage leads the current in the circuit by 90 ...
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1answer
35 views

Does powering both phases (left/right rotation) of an AC motor hurt it?

I know that one can reverse the direction of an ac motor by powering the different starter windings. If you power one starter winding, you create a magnetic bias, allowing the motor to rotate to that ...
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1answer
60 views

Low Voltage, High Frequency, High Amperage Power Supply Design

For an ongoing project of studying magnetic properties of various metals we need to use a power supply which can generate 25 V peak to peak, frequency 50- 500 kHz, 5A (PP) current. Frequency would be ...
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2answers
19 views

Relationship between power angle and real and apparent in ECO dataset

I am trying to parse the ECO dataset, which includes 1-second electric data collected from residential houses. Link to dataset: http://vs.inf.ethz.ch/res/show.html?what=eco-data But the relationship ...
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2answers
141 views

Phasor to Rectangular Confusion

I'm doing an assignment on circuit analysis with phasors and it's brought up a point of confusion for me on how Phasors convert to rectangular form. My textbook defines phasors as $$v(t) = V_M\text{...
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3answers
269 views

Why does AC input have a parallel resistor and capacitor?

Well, I am trying figure out a situation with images and a circuit diagram. I am checking all part looks normal, but if I insert this board on a machine the resistor is exploding and one leg of ...
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0answers
36 views

Phase angle in a series RC circuit

I have a simple question from an electronics textbook (Electronics Fundamentals, Pearson, 8th Ed., p510 Q 37): 10V 10 Hz AC supply, 4.7K resistor and 10uF capacitor in series, with Vout measured over ...
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1answer
28 views

Reverse Phase Dimmer MOSFETs

I have a comprehension question regarding the design of a reverse phase dimmer. I have a picture attached of the part of the circuit I do not understand: The line is connected to the Drain of Q2 and ...
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1answer
36 views

Power line surge on the Active and Neutral line

Since a while, I've been having massive powerline spikes on both the Active and Neutral line. It happens when I turn on a light (with a trafo attached to it), or have an ESD with my floormat, or when ...
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2answers
49 views

AC/DC amplification

I'm kind of new to this and hope someone with more experience can give recommendation or even a schematic suggestion. I have one function generator (Agilent) and one DC source (Agilent). The signal ...
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0answers
46 views

How exactly does a matrix converter work? Is this even a question that could be answered without months of study?

I learned a while ago about the matrix converter, a type of power electronic device that, I'm told, does direct AC-to-AC conversion without an intermediate DC step. I'm told it can convert input AC ...
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2answers
40 views

AC circuit analysis with a transmission line involved

I'm trying to perform an AC analysis of a circuit that contains a piece of coax cable. The input voltage 'Vs' is a swept frequency (1MHz-150MHz) voltage source with constant amplitude. What I'm ...
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1answer
22 views

What is the typical load resistance for a thermostatic circuit?

I’m looking at retro-fitting a dehumidifier with a condensate removal pump to eliminate the need to empty the bin (daily during the summer); specifically this pump. This pump has a safety switch ...
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0answers
36 views

Can I use a plug rated for a DC circuit in a low voltage AC circuit?

I have an spare 2-conductor plug rated for 12VDC at 5A from an old project. I’m now working on a Class II low voltage (24VAC) projet for which I need just such a plug. Is the plug rated for the DC ...
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1answer
79 views

AC MOSFET Switch

I'm trying to use MOSFETs to allow or block 450kHz sine wave. Here's the test circuit: At low frequency, MOSFETS are totally able to switch on and off. But when the frequency becomes higher at 450kHz,...
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1answer
70 views

How to wire an old single phase AC brushed motor to be reversable

I have searched several forums and found a lot of interesting stuff, but nothing yet that really applies to my situation. I have an old Westinghouse FH motor 1 1/2HP single phase brushed AC motor. ...
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1answer
83 views

Understanding of electrical circuit ( having trouble )

Suppose we have 2 circuits : One is this: simulate this circuit – Schematic created using CircuitLab We call that a circuit. And the second is this : simulate this circuit How will the ...
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8answers
158 views

Inductor with AC source

When an AC source is connected with an inductor we have a continuous change in voltage and current across the inductor. According to Farady and Lenz law we will get an equal and opposite voltage ...
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0answers
30 views

Can I run this circuit with only one AC line in?

I had a problem hooking up P2634 Velleman Quad Triac Switch card today and vaporized the trace between the Positive VAC and the outputs (denoted by the red lightning bolt in the picture). I didn't ...
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1answer
47 views

Phase difference between source voltage and inductor voltage

What will be the phase difference between the source voltage and the inductor voltage? Will the two voltages be in phase or will be out of phase. How much out of phase they will be? Note that there ...
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0answers
45 views

Why is the true power so low when adding inductors to the circuit?

For an electronics class, we used a vacuum pump that works with inductors and measured the current in the system. This creates a phase shift, where the current lags the voltage, as is expected. We ...
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2answers
90 views

AC Neutral and DC com

I have an AC signal that is isolated after a transformer and is an input to inverting summing op amp, and a DC circuit which supplies voltage as an offset to the same summing op amp. The AC is 1 VAC,...
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1answer
48 views

Will this IGBT switch operate correctly?

I am working to design a static AC switch using an IGBT module. The idea is that the switch will protect an inductive load from an adverse voltage condition (such as excessive under or over voltage) ...
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5answers
4k views

AC mains on DC ground

I have a very simple question. I have an array of AC to DC converters from well known companies such as Meanwell, Delta Electronics, Recom Power, XP Power etc. They take my 230V 50Hz AC mains and ...
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1answer
37 views

Calculating Energy Consumption Using a Current Sensor and Voltage Sensor

I'm creating a PCBA that uses a hall-effect sensor to measure current and a transformer rectifier design to measure the mains voltage. The voltage is 110-240 V, ~60 Hz. I wrote a digital filter and ...
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1answer
118 views

How to safely ground a device plugged into an isolation transformer

I am working on an old turntable power supply on my workbench. I have acquired a 1:1 bench isolation transformer to increase safety while doing this. It seems to be a well known "issue" with at least ...
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3answers
417 views

Do function generators produce AC signals in the sense we know?

When I examine function generators, there are a wide range of products. I see products between 7 USD and 600 USD. If they can do the same job, why is there so much difference in price? I can't make ...
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3answers
51 views

What are the specific scenarios that an isolation transformer is useful for avoiding?

I have a home workbench and do minor refurb work with old turntables and monitors (CRT) etc. That implies potential exposure to high voltages (mains or above) at power supply capacitors, etc. I have ...
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2answers
50 views

What happens to the voltage across an inductor as the frequency increases? [closed]

My professor told us before that when DC is passed through an inductor and reaches t = infinity the element becomes open. How does this happen? By the way: the inductor has no charge at t = 0s.
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5answers
108 views

Why should a fuse be installed in live instead of neutral?

I understand why it should be installed in positive instead of negative side in DC, but this is AC. Direction of current reverses half of the time. It is said that installing a fuse in neutral causes ...
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1answer
60 views

Low/Mid/High 230V Fan Control with RaspberryPI

I have fan 230 VAC 300 W, Relay SRD-05VDC-SL-C, and RaspberryPi, what other equipment i would need to be able to control Fan 230VAC with RaspberryPi? I want to go 0/1 with relay, and in mode:1, be ...
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0answers
34 views

Compensating for Feedback Capacitance

I'm trying to build a two stage opamp inverting amplifier with a gain of ~90 @160kHz. The purpose of doing multi stage amplification is so I can have a high input impedance along with the first stage ...
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1answer
77 views

Mains voltage PCB design [closed]

I am trying to design a PCB with AC mains which is going to be controlled using relays to turn on fans and heater. I have never designed PCB for AC. What should I look out for and what should I be ...
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2answers
98 views

What is the use of fast diodes vs rectifier diodes?

I read https://new.abb.com/semiconductors/Diodes/fast-recovery-diodes And it makes fast recovery diodes sound like it’s only for converting dc to ac while rectifier diodes are for converting ac to ...
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2answers
64 views

Does an antenna still receive signals without a resonator?

I want to amplify the signal before separating the frequencies out but I don’t know if the antenna even receives signals without being connected to a resonator. I want to connect the antenna directly ...
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0answers
53 views

Can a 450 V AC starter motor film capacitor bear 300V DC?

I know AC and DC ratings for capacitor differ. But when it comes to film (polyester) capacitors and more in general non polarised capacitors, I ask myself if, given only the AC rating, it is possible/...
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1answer
41 views

Where in AC the charge gets its energy again?

I'm quite new to electronics. Most of the tutorials I've watched are DC oriented and it's pretty clear that there's a voltage drop across the DC circuit. When current flows through components in DC, ...
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1answer
68 views

Why does this AC axial cooling fan have 3 wires?

I'm restoring a 1970s HP Frequency Counter and went to replace the 110V AC tube axial cooling fan on the unit to discover that it has 3 wires. The original fan is a ROTRON 1 PH CAP 0.25MFD fan. I'm a ...
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4answers
57 views

when two computer communicating(sending and receiving) with each other through the twisted cable, then the current in the wire is ac or dc?

cables that connect the two computer system carry ca current signal or dc current signal? when two computer communicating(sending and receiving) with each other through the twisted cable, then the ...
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1answer
26 views

Safe to use both AC and DC with 4 channel relay?

I'm using a Sonoff 4-channel relay and I'd like to use one relay to switch 120v AC and another relay to switch 5v DC. Is this safe to do?
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1answer
48 views

24VAC relay coil buzzing when switched on

first time in here! I designed a simple PCB to accomodate a relay, meant to switch a 230VAC(50Hz)- powered lamp using a 24VAC command signal. I used an ABB CR-P024AC1 (properly rated for my ...
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5answers
254 views

What are the reasons behind marking neutral and line terminals on a power supply AC input?

Even though AC has no polarity, almost all the power supply AC inputs or most AC powered device input terminals indicate line and neutral terminals as L and N just like in the following example: Is ...
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2answers
37 views

Need to operate ac appliances using 5V, 10A relay module with ESP8266 node MCU. How to do it. Please explain the schematics elaborately? [duplicate]

I am having problem in triggering the 5V relay with the output GPIO pin of ESP8266 node MCU. I think the voltage provided by the output GPIO pin is not enough to trigger the relay. I'm thinking of ...
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1answer
56 views

Driving car electrical vacuum pump

I am trying to drive an electrical vacuum pump from a car directly from 12 VDC. Earlier, I succeeded with a different pump just by connecting them to DC power, the other pump (different brand) used ...
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4answers
120 views

Can reversing AC polarity of one of two adjacent LED bulbs reduce overall flickering in a room?

Can reversing ac polarity of half of the bulbs in a chandelier bring the flickering out of sync (out of phase) so that half of the bulbs are ON while the others are OFF? I mean the AC polarity of the ...
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3answers
67 views

Is it possible for any circuit to independently make its own trigger, sweep or oscillation without the aid of an AC sine wave?

Even a Schmidt trigger, attributed to being able to create the start of an oscillating circuit, has to get its start from an AC sine wave. It seems that no amount of tubes or transistors can ...
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1answer
47 views

AC Motor Induction Diagram

I have a question with the following information "AC motor connected in series to 400v RMS, 40A RMS, pf = 0.707" It wants me to draw a diagram, my question is: Can I model the motor as a single phase ...

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