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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.

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1answer
60 views

What is the reason that moving iron instrument can measure both AC and DC but moving coil instrument can't?

What is the reason that moving iron instrument could measure both AC and DC but moving coil instrument can't? ( moving coil can't respond quickly as the AC changes its direction so stays at zero - is ...
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6answers
8k views

What is going wrong in this circuit which supposedly should step down AC to arduino friendly voltage?

So I'm using this circuit but when adapter output is disconnected and only midpoint terminal of the transformer is connected the Arduino input pin reads some mV. mid point reads perfect 2.5V. What am ...
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0answers
41 views

Wiring AC motors in parallel

I am having some Somfy motorized curtains installed in my home, but I struggle to understand the following statement in the manual: Wiring multiple Sonesse 40 WT's in parallel will result in damage ...
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1answer
20 views

Example of Electrical Apparatus that draw leading VARS and Electrical Apparatus that draw lagging VARS [on hold]

I understand that an AC inductive circuit will draw lagging vars while a capacitive AC circuit will draw leading vars (ELI the ICE man), but what are some examples of real-life electrical apparatus ...
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1answer
37 views

Alternating Voltage

Is AC the same as an alternating voltage ?
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1answer
48 views

How do I calculate the voltage across a capacitor when the source is a square wave?

I have a series RC circuit with R= 2.2K Ohm and C=100 nF, and the voltage supply is a 2.5V peak square wave. And I'm not sure how to calculate the voltage across the capacitor.
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3answers
40 views

How does one determine the type (AC v. DC) and operating voltage of small motors?

I've become fascinated by Rolling Ball Sculpture (RBS) and plan to start building my first one soon. Typically a RBS uses a low-voltage, low-RPM motor to carry the marbles to the top of the structure ...
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0answers
34 views

AC Current Source - Modifiable Amplitude and Frequency

Just a heads up, I am not an electrical engineer. I need to build an AC current source of the following specifications. I have looked into IC chips, but none meet my specifications. I have started ...
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2answers
64 views

Clipping an AC line voltage

I've got a linear step-up transformer (120V AC input) which has an output that under load nominally supplies 230V AC @ 100mA. But with no load it floats to as high as 280 V. I need to switch the load ...
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3answers
137 views

Why does a capacitor charge faster when there is a diode connected?

In an series RC circuit why does a capacitor charge faster when there is a diode connected in parallel with the resistor? I tested on an oscilloscope, using a square signal and this is what I got. ...
2
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1answer
79 views

Why is there 130V between my laptop charger ground, and Raspberry Pi 5V Supply Ground?

I noticed that I was getting mild shocks while touching my plugged in laptop and touching a metal shielded USB device plugged into the USB port of my Raspberry Pi 3 at the same time. I used a multi ...
1
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1answer
32 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 ...
2
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1answer
63 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
34 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
36 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
71 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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0answers
53 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
98 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
365 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
37 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 ...
1
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1answer
66 views

Series RC circuit phase difference [closed]

I have a series RC circuit . AC sine wave source peak to peak voltage is 4Volts.In I=V/Z formula I don’t know what should I write the Voltage.Should I write Voltage RMS value or Peak voltage value? ...
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0answers
38 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
74 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
37 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
43 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
45 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
59 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
57 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
73 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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votes
0answers
91 views

Voltage regulator not outputing desired voltage and extremely hot [duplicate]

Now that I have understood how to connect my transformer to output 18V, I now have a huge problem with heat and wrong output voltage. I also smells and you can feel the heat. Here is my design ...
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1answer
44 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 ...
3
votes
1answer
93 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
130 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
97 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 ...
1
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1answer
49 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 ...
1
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0answers
44 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
45 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
50 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 ...
0
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1answer
103 views

Is this DIY high voltage AC generator safe to use?

Making a DIY type high voltage AC power supply from 40 W soldering iron, 220 V AC to 12 or 6 V AC step down transformer and 5 A fuse. These things are ALL connected in series to the 220 V AC mains. ...
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0answers
49 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
47 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
89 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 ...
5
votes
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 ...
0
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1answer
35 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
39 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 ...
1
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1answer
61 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
51 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
93 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
39 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
51 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 ...