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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.

215 questions with no upvoted or accepted answers
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Conditions for maximum power transfer in an AC circuit

So, if we're given the circuit below: Known values are: \$E_g=35 \ kV\$ \$f=685 \ kHz\$ \$\underline{Z}_g=150 \ \Omega\$ \$\underline{Z}_p=(200-j300) \ \Omega\$ We have to calculate \$L\$ and \$C\$ ...
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59 views

Why should the primary winding of the transformer not be grounded?

I've been wondering what would happen if you grounded both star points of a Y/Y connected transformer. This shouldn't affect the voltages, so why really is it not advised to earth both the primary ...
2
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1answer
72 views

Are large pulsed currents the most deadly type of electric shock?

As opposed to sustained electric shock via DC or AC? I might be wrong, but when people are killed by electrocution it is usually due to a large current of very short duration passing through their ...
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1answer
130 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
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1answer
101 views

My triac turns on when gate attached to vcc (good)… but also when connected to ground (bad)

I'm still really new at working with triacs and understanding them, but I want to make a circuit that allows a microcontroller to turn on/off an AC signal (very low power, not mains, don't worry) to ...
2
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1answer
109 views

Is the Gummel-Poon model useful for explaining AC transistor amplification?

Let me be clear: By amplification I am talking about the process of boosting the strength of an AC signal. Thus, where the output power to input power ratio is greater than 1. Now suppose we have a ...
2
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0answers
275 views

What's wrong with my input circuit? LTspice

I am designing my first power electronics board in LTspice to convert single phase AC to DC. This DC is fed to asymmetric bridge to drive an SR motor which is connected to a flywheel. This flywheel ...
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0answers
214 views

Tricky AC power Question

Greetings all, Just to be clear, I am not asking anyone to do my homework. I am simply asking for guidance and or to clarify any conceptual errors I am making. For the following question, ...
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2answers
124 views

Circuits of AC - impedance

I have a question regarding impedances. While it is intuitive that \$ R \$-element has impedance \$ R \$, it's not so easy for me to figure out impedances of \$ L \$ and \$ C \$. Here is my, probably ...
2
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1answer
402 views

ac voltage regulator

I'm trying to built a circuit that amplifies music from a phone to a headset, based om ambient noise level. So if you're surrounded by noise, your music volume will turn up and in silent surroundings ...
2
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0answers
823 views

Calculating signal attenuation for AC?

So we've got this; simulate this circuit – Schematic created using CircuitLab Which I've been told is equivalent to the sum of it's Coutputs to an AC signal; simulate this circuit So then; $...
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0answers
748 views

Why does a multimeter in resistance mode show initial continuity over a diode?

I originally phrased this question very differently; the original text is retained below in case background information is useful to clarify the context. When I using this digital multimeter to ...
2
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1answer
122 views

Is there a pattern to where various industrial AC voltages are used?

AC voltages in the "low voltage" class vary quite a bit. I've seen nominal voltages of 208, 220-240, 277, 380-415, 460-480, 575-600, and 690 VAC. Past that I don't see anything until medium voltage ...
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0answers
69 views

Measure 220V alternating current with a multimeter in DC mode

What happens if we measure 220V AC from wall socket with a multimeter in DC mode (instead of AC)? If I remember correctly, it should show the average value of this sinusoidal 220V, i.e. 0V. Is ...
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0answers
58 views

How is AC load distributed across on-site generation and the utility?

I’m trying to understand the physics behind AC load distribution when distributed on-site generation is installed and the load is also connected to the grid. In the diagram below, I have a building ...
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0answers
71 views

Apparent lack of rigor in Phasor domain analysis of steady state AC circuits

so I have encountered a hitch in my understanding of analyzing steady state AC circuits. I have looked everywhere for the answer to my question and I can find nothing. Usually when we analyze ss AC ...
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2answers
71 views

Current flowing in an open circuit to make it the same voltage

I've tried to research this answer for quite some time but i'm struggling to find a proper answer. I think my question falls between antenna theory and batteries. So in a dipole antenna we supply a ...
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1answer
29 views

I want to handle the voltage and current spikes from inductive load of 220V AC ceiling fan

I am trying to regulate speed of 220V ceiling fan from Arduino but unable to handle the reverse voltage and current though I am applying the flyback diode across inductive load.
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0answers
53 views

How do portable batteries with AC outlets handle the ground pin/wire?

There are many portable batteries ("power stations") that have AC outlet(s) with – what looks like – a dummy ground pin. From what I can find in their manuals, it doesn't seem like these devices are ...
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1answer
71 views

Admittance, Conductance, Susceptance definition

Admittance is the reciprocal of impedance. But: 1) Susceptance is the reciprocal of reactance, or the imaginary part of admittance ? 2) Conductance is the reciprocal of resistance, or the real part ...
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0answers
114 views

TRIAC broke (literally) – why?

I have built a circuit according to Dimming 230V AC with Arduino, with two output channels. The basic principle is: An ATtiny does zero detection via an optocoupler; when AC crosses 0 V, it triggers ...
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0answers
118 views

What is maximum symmetrical output voltage swing in this case?

I'm pretty new to Electronics and hence the following doubt. I could not understand how the authors reasoned out the swing limits for this problem ((b)-part only)
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63 views

Measure low AC Power consumption (oscilloscope? MCU?)

I would like to measure AC power consumption of devices such as AC/DC charger, AC LED bulb or an electric circuit in the main box of a house. However, their power consumption are quite low and the ...
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0answers
401 views

Snubber for Relay Contact Switching Resistive Load

I am working on a redesign of some circuit boards and am looking for a way to save space and potentially switch to surface mount parts. Some of the largest through hole parts in use are for an RC ...
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0answers
50 views

Transformers and high voltage elements

I've been trying to learn how to properly set up a circuit for power regulation. Often I hear for domestic use that it is better to use a transformer to isolate the device as well as stepping down the ...
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0answers
114 views

Protecting malfunctions in relays which operate roller shutters (motor, inductive load)

I have a circuit used to control roller shutters in my home, which roughly can be seen in the schematic below. simulate this circuit – Schematic created using CircuitLab It works, but after ...
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0answers
340 views

How to increase the speed of a specific AC motor

Here are details of this project: The motor being used is a 2 phase Slo-Syn model SS400 (1/4 HP). The motor has two 120V windings that are physically 90 degrees to one another. It is operated by ...
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1answer
915 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 ...
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1answer
147 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 ...
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0answers
155 views

Use of DC source in Zener clamping circuit

A question in my engineering degree asked me to design a clamp circuit that gives a 10V 50Hz AC signal a +5V DC bias. I designed the following circuit as my answer: I assumed 0.6V forward drop for ...
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1answer
59 views

12VAC Common Reference

Working on a design where power supply (on the PCB) is 12VAC to full wave rectifier to 5VDC linear regulator. Customer switch box is also power via same 12VAC source and will be switching that 12VAC ...
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1answer
93 views

Power IR2110 from a low voltage AC Source

I am trying to power the IR2110 using an AC Source. However, this source is also connected to a full wave bridge rectifier that's going to supply a controlled buck converter. I tried using a voltage ...
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2answers
76 views

AC capacitor computational problem using calculus

A current is flowing through an ideal capacitor, C = 25μF, the current waveform is a sawtooth. I need to find the formulas that plot the voltage waveform ,which is also shown in the figure,right below ...
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0answers
90 views

Am I right about measuring current, and power

I have a meter that can measure: current, active power, reactive power and complex power. simulate this circuit – Schematic created using CircuitLab So, when I measure the four things: current,...
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0answers
87 views

Trying to find the signal in an AC line

I have a medical office call box/light system that is older probably 20 year old and they moved the main panel that the Drs see to know when there are patients waiting and since they moved it, it is ...
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0answers
46 views

Calculate current on tri-phase circuit with parallel resonance

I'm struggling with the following circuit. data are: E1=10V (three phase 120°) \$\omega\$=20 rad/s XC=-10 R=10 XL=10 About VGO I calculate the tri-phase voltage as $$E=\frac{10}{\sqrt{3}}=5,...
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1answer
240 views

HVAC fan relay intermittently sticks closed; opens when touched

I have constructed a simple OR gate using two HVAC fan relays to control a 120VAC/1.5A booster fan for my home HVAC system. I have a zoned system, with multiple thermostats, but only one zone/...
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1answer
215 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 ...
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0answers
109 views

Identifying this connector

Can anyone identify this connector? Found inside a Panasonic fan.
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0answers
60 views

Describe this type of rotor from a three phase induction motor?

After CNC machining the rotor, to expose the outer surface of the silicon iron, this proves to be exactly the same as the inner surface was (the one facing the core).Just plain electric iron rings ...
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1answer
115 views

Help designing a voltage ramping circuit

I'm trying to design a circuit that starts at 0Vrms and ramps up to 3.4Vrms sine wive over five(ish) cycles, then stay at 3.4Vrms until it's turned off. It doesn't need to ramp back down, however. The ...
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0answers
544 views

Unexpected results measuring AC from secondary of toroid transformer

I am trying to measure AC voltage from the secondary of a toroid power transformer, and I am baffled by what I am seeing. The AC measurement (less than 4 volts) is too low; the transformer is rated ...
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0answers
255 views

How to synchronize current from an AC and DC current

I'm trying to make a battery less solar grid in which energy from the solar panel will be directly given to home appliances and will be complemented by current from the grid. I'm thinking of passing ...
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1answer
583 views

Control a 12 v circuit using wall plug 220v ac timer

I want to use a standard supermarket 220v ac timer to switch a 12-volt circuit. I was thinking about letting the timer run on the outlet, and just desolder the relay separating it from the ac, keeping ...
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0answers
89 views

Low voltage LED bulb or jump into line voltage?

I'm not even sure if this is appropriate StackExchanage community for this but I wasn't sure where else this sort of question would fit. So I tinker with electronics here and there and primarily it ...
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0answers
1k views

How to safely create an AC short circuit?

The company I work for builds products that typically have integrated fuses or circuit breakers. During our product validation testing, we would like to begin integrating a test which will basically ...
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0answers
128 views

Microcontroller reset on mains connection

I'm helping someone build a static VAR compensator. We figure it'll be evident that the power factor is being corrected if there's a display that shows AC voltage and current waveforms, so one can see ...
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0answers
421 views

Calculate noise spectral density

I want to analytically calculate the power spectral density (PSD) for noise at the input of the given circuit as a function of frequency. Both resistors cause noise, as well as the opamp itself, with ...
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0answers
297 views

Calculate input impedance of transmission line without knowing L or C

I have the following problem: A TV antenna lead-in wire 10 cm long has a characteristic impedance of 250 ohms and is open-circuited at its end. If the line operates at 400 MHz, determine its input ...
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0answers
37 views

How to integrate NEMA x-15-P into mechanical/electrical design

What are some ways (or what is the typical way) that a wall mount device mechanically and electrically attaches the AC blades/plug into a design? I've worked with panel mount IEC320 and cabled power ...