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
157 views

PSpice AC Circuit Simulation Showing 0 V for Output Voltage?

I am trying to run a simple Op Amp simulation. My lab gives zero instruction on PSpice, tossed us a brief manual on DC PSpice circuits (even though the class is AC), and said go forth. The circuit I ...
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1answer
88 views

How to measure 0.02V to 0.18V audio signal with arduino?

I have a Sony STR-DE845 home theater amplifier with 8 Ohm speakers. I want to measure the voltage sent to the speakers to infer their volume using an Arduino. The AC voltage measured across a speaker ...
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1answer
58 views

Why a pure resistive AC circuit absorbs power at all times according to this equation

Here is the equation of average power in a pure resistive AC circuit: "Fundamentals of electric circuits - Alexander Sadiku" How this equation imply that the circuit absorbs power all times, I ...
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1answer
40 views

Create a polar cap with a diode?

I'm trying to order components, so I can make a board following this circuit. My problem is, I cannot find any 0.1uf capacitors, that are rated at 275VAC. The highest voltage I can find, in stock, is ...
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3answers
117 views

Chop Saw Inrush Current Limiter?

I have a Dewalt Metal cutting abrasive saw that tends to open a breaker on starting up. It draws 75A on startup tripping the magnetic part of the breaker and opening it. This circuit is only to stop ...
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62 views

Does anyone know the UL standard related to resistors and isolation on AC mains?

I have a circuit that is attempting to measure AC line voltage 120-240V but I was told by the certification test lab that my voltage divider resistors would require an expensive 3 week soak test. The ...
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2answers
118 views

Am I safe working with a power supplier of 12 DC connected to the AC wall socket main line?

I'm working on an electronic home experimental project. But I have always been afraid of the issue of electricity since it can electrocute. My question is.. Am I safe working with a power supplier ...
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2answers
420 views

LTSpice: When running a linear AC simulation, how to view the voltage ratio between two voltages?

For example, how would I see the ratio between Vi and Vo for a linear AC simulation?
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0answers
43 views

How to calculate R for an AC load on a 3-ph system

I'm trying to calculate the resistors in an AC dummy load for a 3-ph system. A simplified schematic can be found below. The idea is to switch (with regular AC 1-ph contactors) some resistors on each ...
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0answers
50 views

Build 100-240v Power Adapter

I am trying to power a 5v circuit from any voltage between 100-240v. I know it is possible to do this with a transformerless power supply, but only for a single voltage (e.g. 120v only), but how do I ...
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1answer
106 views

Purpose of high pass filter for AC Mains?

I wanted to ask what the purpose of the high pass filter does in the below circuit. Is it necessary?
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0answers
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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2answers
92 views

Question about diode clamper

I have 2 problems with diode clampers that I don't understand First, in this circuit for example: In the positive half cycle, the voltage across the diode is the diode drop of 0.7 V Then the ...
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2answers
49 views

Small utility heaters

I have found myself needing small heaters, in the 5-10 watt range for various applications in diy projects, preferably powered from 120VAC. The exact wattage is not important, and doesn't have to have ...
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1answer
113 views

Realise circuit for hFe measurement

To measure Beta (hFe) of the transistor you should zero u_ce (voltage across CE for the AC component in signal). To zero that component you put capacitor in parallel with transistor AND as shown on ...
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2answers
70 views

Output of AC op amp circuit has unknown superimposed signal on top of expected output signal

I am trying to find the voltage gain of a certain ideal op amp circuit with a sinusoidal input. However, when I simulate the circuit, the output shown seems to be my calculated output but with a ...
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3answers
151 views

Rounding up or down with Motor Overcurrent Protection

When sizing motor over-current protection, CSA 22.1 28-200 3a states that a circuit breaker can be sized up to 250% of the rated full load amperage (FLA) of the motor. E.g. 100hp, 575VAC motor ...
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1answer
48 views

differential amplifier and ac imput

hello im studying the differential amplifier from Sedra Smith and i have problem with the ac mode when the signal is differential (vid/2 and -vid/2) I know that in Nmos transistor the current flows ...
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1answer
127 views

Resistors parallel with motor?

A pcb we've been asked to look at has two 15k 1W resistors in parallel with a 15A AC motor. Silly as it sounds, we're a little stumped why they're there. It's probably bloomin' obvious, but we can't ...
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2answers
235 views

What is the purpose of diode in parallel with the resistor divider in MOSFET gate driving circuit

I have built several 200W AC dimmers using Microchip 8-bit CPU and the illustrated back-to-back MOSFET circuit. I have seen on Internet schematics with the D1 diode in parallel with the R1 resistor, ...
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1answer
111 views

Treadmill causes nearby electronics glitch

I don't know if it is right place to ask, if not correct/guide me. I recently have built treadmill workstation, where I could walk and work (rather than just sitting). But as soon as I turn on ...
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1answer
53 views

True replacement for MOSFET Infineon SPD04N50C3

I have built many 240V AC dimmers with back-to-back Infineon SPD04N50C3 N-channel MOSFET transistors without any problems. Unfortunately they are not manufactured anymore. I found a replacement from ...
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0answers
407 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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1answer
62 views

AC/DC power supply module with 20mA output current

i want get 20mA current with 24V ac to dc. I have found this power supply module with 6-9A output current but i need max 20mA. What can i add with this module to achieve my settings? I am powering ...
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2answers
60 views

AC motor design

Is it possible to have an AC motor with only a partial stator, one that does not fully encompass the rotor? Refer to the picture to understand what I mean. This would be needed to drive a spherical ...
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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
69 views

Advice for PCB layout 230V AC to 18V DC with another function (beginner continued)

I am continuing a thread Beginner's second PCB circuit design: AC to DC Does this PCB design look better than the previous and do you understand it? I also want to know if the terminal blocks ...
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1answer
94 views

Circuit drawing more current on PCB [closed]

I have a circuit that I developed on breadboard. I have then soldered it on a PCB and it is now drawing more current on PCB compared to when it was on breadboard. I only want to discuss possible ...
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5answers
3k views

Beginner's second PCB circuit design: AC to DC

I am designing an AC to DC converter and I just want to make sure that I am so far doing the right thing — placement of components and wiring etc. — as I am a beginner. Does this look ...
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1answer
94 views

Transformer fuse for primary coil. 240V with 16VA

So I know it may be a basic question but hear me out. These are the specs for the transformer I would like to buy. To add a fuse to the primary coil I would do 16VA/240V which gives 0.06A. Does that ...
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2answers
103 views

How does the power efficiency of an appliance compare using 12V DC or 240V AC with an inverter?

With an off-grid system, if an appliance supports powering via both 12V DC and 240V AC, is there any difference with the power efficiency of either method excluding the draw of an inverter used to ...
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1answer
96 views

Help for voltage is being passed trough load, even triac is OFF condition

We are using below circuit for home automation. We are facing problem when 5v battery is not passing to the circuit,but even 1 volt is being passed trough load, even triac is OFF condition.. Please ...
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1answer
209 views

Explanation of a sample circuit for the FL5160 Dimmer controller

While looking for dimmer circuits, I stumbled upon the FL5160 Dimmer controller and it's specification at https://www.onsemi.com/pub/Collateral/FL5150-D.pdf The example schematic (for example, the ...
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1answer
98 views

Is a safe 110/120VAC benchtop power tap possible?

I have a benchtop power supply that provides +3.3, +5, and +/-12VDC. I've started cannibalizing small appliances for parts, and I'd like to have similar power taps for 110/120VAC. Does such a thing ...
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0answers
115 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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1answer
61 views

What determines the real world transformer ratio of a clamp on AC power meter?

The ideal step-up transformer, when the primary coil has 1 winding and the secondary coil has 60 windings would step up the voltage 60 times. With this improvised clamp on AC power meter, which is ...
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5answers
423 views

Why do we use alternating current and not direct current for mains power plugs within a house? [duplicate]

I understand that for transporting electric energy it makes way more sense to have AC. But within my house, I don't think that argument holds any more. Devices I use (roughly ordered by power ...
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0answers
26 views

Calculating Currents and Voltages in and AC RL Circuit provided below

I am studying RL Circuits with AC sources. I am trying to solve this circuit So far, I am only able to calculate the current iL through the inductor as for the other parts I can't grasp the concepts. ...
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2answers
80 views

Railway overhead lines: What happens to other two phases in single phase railway power?

This is actually two questions. As my imagination I have the German/Swiss/Austrian/Norwegian/Swedish railway system on mind (15kV, 16.7Hz). I think conceptually the problem is the same on other AC ...
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1answer
153 views

How to design an AND gate for 24V AC Thermostat Connection

I have a two stage furnace with a heat pump, and a thermostat that isn't capable of controlling the second stage of the furnace when in heat pump mode. However, I can configure it in such a way that ...
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0answers
20 views

AC servo motor driver problem (new, more precise) [duplicate]

I was not precise in last question. My AC servo motor driver "panasonic MSDA023A1A" which I use on CNC cutting machine is started to display alarm code "Err_18", which stands for regenerative ...
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2answers
102 views

Question about AC servo motor driver

Does anyone know what means when AC servo motor driver displays error code for "regenerative discharge", and stops working. What this mean in practical situation. This happens from 1 to 10 minuts ...
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0answers
31 views

Can a MTS 101 2 pin ON-OFF switch rated for VAC be used in a DC circuit?

I'm currently looking at buying a bunch of MTS 101 rocker switches which are rated for: AC 125V 6A, AC 250V 3A For DC the rating is not available http://www.massuse-relay.com/details/MTSSeries.pdf ...
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2answers
110 views

Why a CFL lights up when I touch it?

When there is a very low voltage (AC), even for a compact fluorescent lamp (CFL), it glows very dim (orangish in color) at the beginning of the glass but when I hold the glass just for a second, it ...
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2answers
347 views

Permanent magnet synchronous motor (PMSM) equivalent circuit

I am trying to model a PMSM (permanent magnet synchronous motor) in LTspice and in order to do so I need to form an equivalent circuit. Through some research I believe the circuit should be formed in ...
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1answer
169 views

Calculate torque from current induced in a single phase of a 3 phase AC Induction servo motor

I'm looking to measure the torque or slip angle on an AC induction (asynchronous) servo motor given the current induced in one of its phases. The servo and drive is yaskawa. Example data is shown ...
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1answer
74 views

Input protection on a DC jack

I am designing an battery powered instrument with around 20-40Ah 3S li-ion batteries in it along with a 10A 3S(12.6v) external charger. Due to ease of availability and the current capacity I have ...
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0answers
52 views

AC Circuit Analysis with Diodes and Op-Amp

The following circuit is given: The 2 diodes are idealised in the following way: All other parts have the following properties: I've been trying to figure out what the voltage at the entrance of ...
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2answers
169 views

Voltage Equation in Time Domain

When we describe a AC signal (voltage is this case) in time domain we use an equation something like this below: \$v(t) = V_m \mathrm{sin}(\omega 𝑡 + \phi)\$, where 𝜔 is the angular frequency of ...
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38 views

Ac signal of soldering iron tip

Did you noticed that when holding a LED with bare fingers and connect it to a soldering iron(ac type) it gets a little bright. I did it for other components to reduce their heat during the soldering. ...