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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32 views

TRIAC not triggering

I am attempting to make a circuit that would allow me to control a standard CFL 13W lamp with a microcontroller. As the lamp would run on AC power, I am making use of the following circuit using a ...
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43 views

Wiring for industrial applications

If I am buying wire to be used in a damp environment, and I need a ground wire for an AC device, can an insulated third core act as a ground wire? I don't know what effect having no insulation has on ...
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87 views

Impedance in sine DC

If we have a DC sine signal. Can we say that capacitors and inductors have impedance despite not being AC? If yes then what will the formula look like? And the opposite if we have an AC square signal ...
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47 views

Conversion of AC to AC problem [closed]

I am trying to convert AC of one frequency to AC with a second frequency.I know I have to convert first the AC to DC.I am using a full bridge rectifier for this: Then i will take this sine dc to be ...
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67 views

Convert AC to different frequencies [closed]

How can we convert AC with a frequency of 5Hz to AC with a frequency of 10Hz.I considered using a transformer but the output signal of the transformer has the same frequency with the input signal. How ...
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1answer
65 views

Arduino freezes due to: power supply?

This is going to be a long question but I don't want to leave any loose ends. I'm developing an incubator which includes a hot air pump to conduct heated air through a hose to a closed chamber (~100 ...
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45 views

can I use neutral in an AC circuit as the negative conductor on a separate DC circuit

I have a particular application, but I also generally want to know the answer. I have an aluminium sail boat that has a extensive DC electrical system, as well as a 500watt inverter for a basic AC ...
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1answer
19 views

Correct AC input wiring for electronic door lock PSU

I have a small PSU that outputs 12v DC for use with electronic door locks, but I'm a bit uncertain about the AC input. From the diagram it looks like there is two AC live wires, and a single earth. ...
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45 views

Resonant frequency and maximum signal width

I've seen resonant frequency being defined as the point where the input signal is in phase with the output signal (So reactance/susceptance is 0). However conceptually, teaching material seems to link ...
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2answers
71 views

Soft starter for centrifugal pump [closed]

Do most manufactured centrifugal pumps come equipped with soft starters, and is it a good idea to invest in one if they're going to be frequently switched on/off?
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1answer
125 views

How do you combine 2 AC power sources?

To combine 2 DC power sources, you can diode OR them both together. You can't just directly connect them together because their voltage outputs may differ ever-so-slightly, leading to imbalanced ...
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67 views

How do you determine the direction of AC current? (ex: whether your solar-powered house is drawing from the city power grid or adding to the grid)

I'd like to measure the voltage and current of mains AC power at the fuse box where a house is connected to the grid. Assuming the house has solar panels on it, sometimes it will draw from the grid, ...
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1answer
83 views

Maximum power transfer of transformer [closed]

We have this transformer: simulate this circuit – Schematic created using CircuitLab The power transfered to R1 resistor is maximized when the frequency of the signal is very big.This means ...
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1answer
37 views

RC low pass filter difference with RC high pass filter

This is a low pass filter: simulate this circuit – Schematic created using CircuitLab This a high pass filter: simulate this circuit If we add a load resistor to the high pass filter it ...
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1answer
36 views

Garage door openers - BLDC x AC monophasic - Is that possible?

As far as I know, electronic control boards for garage doors, they basically control two main types of motors: AC induction monophasic, one neutral and two phases, driven by TRIAC or relay. It takes ...
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2answers
48 views

Controlling AC motor with relay vs. switch on motor

Is there a difference in terms of operation between switching a relay connected to mains for an AC motor versus opening/closing a switch on the motor? Would the internal protection circuitry ...
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1answer
33 views

Capacitive reactance related to frequency

Why does capacitive reactance decrease with the increase of the frequency of the applied signal? It is easy to prove why capacitive reactance decreases with increased capacitance. The more we increase ...
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1answer
110 views

What is this symbol on a schematic for an old milling machine?

On the schematic below, I'm having trouble identifying what the symbol drawn on top of motors 2 and 3 means. I've never seen anything like it. They're only present on the high-power spindle and feed ...
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1answer
60 views

how to generate 70V AC from TLP222G-2

I have 70VDC 30mA source I need to control optoisolators to generate 70V AC signal I can use TLP222g-2 dual isolators. to build the h bridge I have a single PWM channel from my MCU. Is it possible to ...
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1answer
45 views

Circuit giving values on both AC and DC

I have a generator stopper which works on 220 volt AC (in India 220 volt AC is normal supply) and has an electromagnet which pulls up a lever and the generator is stopped. It works perfectly when the ...
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31 views

Need an isolator or similar to fix my design issue

I have an arrangement where 0-80 VDC signal is provided as input to a measurement board for measuring this DC signal. But somehow along with this 80 VDC signal, there is noise coming in the circuit ...
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1answer
41 views

Power output only when mains power cut and only bu ups

I have a ups in my home.I want to install a fan in my room which run only when the mains power supply is cut and ups is supplying the power.How can I do this.
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1answer
100 views

What is the advantage of kWh based tariff? [closed]

Electricity consumers are divided into domestic, commercial, industrial , etc based on the power factor. Domestic loads are mainly resistive. But not 100% resistive always. The industrial meters shows ...
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1answer
48 views

Laplace tranfsorm of capacitor functions and initial conditions

I may be asking something trivial, but unfortunately, I could not find an answer so far. Suppose an AC circuit. The voltage of the capacitor is given by $$v_C(t)=Q(t)/C = 1/C [ \int_0^t i_C(τ)dτ + v_C(...
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3answers
92 views

Measuring the waveform of mains voltage using an oscilloscope

I understand this is a recurring discussion, but I still can't find a concrete answer to this question. I would like to know how can I inspect the waveform of my UPS output (230V) using an ...
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3answers
182 views

What is reactive energy?

We know the typical equation for instantaneous power (which can be proven): \$p(t)=v(t)i(t)\$. In sinusoidal steady state (let's ignore harmonics for simplicity), \$v(t)=\sqrt{2} V_{\text{rms}} \cos{(\...
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1answer
31 views

Resistive AC voltage divider and phase

I built myself a power monitor a few years ago that works and I was trying to simplify mine by cutting out an expensive and hard to find 12V ac:ac adapter. I am familiar with a voltage divider and it'...
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62 views

Considerations for converting a LED Bulb from AC to DC power

I was asked by my uncle to convert 22 units of gx53 LED Bulbs that are powered by 230VAC 5W to DC voltage power. The LED Bulb itself consists of 5 LEDs(string) in series, in parallel to another 5 LEDs(...
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2answers
59 views

Vacuum Fluorescent Display: What are the benefits of an AC filament driver instead of DC?

Question is already in the title: What is/are the benefit(s) of an AC filament driver instead of DC for VFD displays? It works with DC so why to invest in an AC driver? Anyone?
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80 views

Why can't the earth discharge my DC batteries?

Electrical newbie here. After watching this video I noticed that in the event of a fault, the AC power in your house can discharge into the earth/ground (which thus causes the house breaker to trip). ...
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1answer
58 views

What is the actual direction of real current in an A.C. generator? From the North pole to the South?

I see diagrams of a current being generated in a loop or square-ish section of wire that is rotating between two magnetic poles... a north on one side and a south on the other... BUT, the current ...
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1answer
89 views

Adding additional protections to a PSU (Meanwell IRM-01-5)

Since I am new here, first I would like to apologize if I did draw this schematic wrong (i.e. lines do cross, etc.). It is a few days that I am using this online editor, so I am still in the learning ...
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1answer
55 views

Why using capacitor in transformer less ac to dc converter

I saw many transformer-less power supplies using capacitive resistance of a capacitor. But I don't know exactly what the reasons are for using capacitors instead of normal resistors . I guess two ...
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38 views

Is there a potential earth leakage or is it something else?

I'm facing an issue in my house since last Christmas. When the lights or appliance with motor in any room are turned off/on the TV would go out and come back on in a short span (as if the power went ...
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38 views

AC switch with two mutualy exclusive power lines [migrated]

I have deconstructed bathroom fan and found three wires coming from the wall: N -- neutral A -- has 230V only when light switch is on B -- has 230V only when light switch is off I wonder how such "...
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1answer
27 views

Clearance and creepage for AC Optocoupler for 230V line detection

I was wondering how I need to handle clearance and creepage in this scenario. It's AC mains line detection circuit. I need to achieve around 2.5mm creepage.
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1answer
24 views

How to simulate two 12W lightbulb in series to 220VAC?

How can I simulate two lightbulb of 12Watts in SPICE? In proteus simulation, there is only a lamp of adjustable nominal voltage and resistance. The default is 12V nominal and 24ohms resistance. If I ...
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2answers
70 views

feedback BJT ac analysis [closed]

I'm having trouble with a BJT question. How can we do ac analysis of this circuit? My attempted solution is this:
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1answer
123 views

what does this bulb need to work properly in this circuit?

This is the circuit, before it was working, but not anymore. I have an identical circuit and its ulb still working. I don't know where is the problem. (https://i.stack.imgur.com/fPpZW.jpg)
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78 views

How can I trigger an AC output ON when an AC input is OFF?

I have a low power 24V AC circuit powering some motorised ball valves for switching water on and off. Several of the valves are 2-wire auto-return meaning that presence of an AC signal will open the ...
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29 views

How to measure the peak startup current for an electric motor?

How would I measure the startup current for an electric motor? For greater context, see https://diy.stackexchange.com/questions/194224/what-kind-of-inverter-do-i-need-for-an-inductive-load/194227?...
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1answer
59 views

Rectify AC and keep the voltage below V_max for DC step down converter

I bought a DC-DC step down converter (MP1584EN), but I found out my input was actually AC (24 V). I plan to use a bridge rectifier with a smoothing capacitor The problem is that the converter is ...
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2answers
207 views

How does this old fan regulator circuit work?

I was on the lookout for an old fan regulator. I had heard that its power consumption was constant at all speeds. I could lay my hands on this 1970 regulator. It appears to be a transformer with ...
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36 views

Wiring diagram sanity check

I am rewiring a relatively old GE OEM motor and the high voltage part of the wiring diagram is marred. I know the motor works on 120V so its not an issue of functionality. If someone who is better ...
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20 views

Ac current injecton to dc bus

I want to inject a 2V ac sine wave on a 480V dc bus. to protect my ac signal generator from entering high dc voltage I am going to use capacitor as coupling device. Ac generator also should deliver 15 ...
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1answer
74 views

Can you turn on a light bulb using only one of the two wires of the wall outlet?

Instead of trying crazy things I would rather ask. I am asking this for purposes of learning. So I have learned that if the voltage is high you can get electrocuted by touching only one side of the ...
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1answer
44 views

How to analize an ideal diode circuit with sinusoidal sources and storage elements (inductors and capacitors)?

In my first Electronics classes, we learned how to analyze a circuit with AC sources and ideal diodes but with only resistive elements. In such cases, the currents and voltages respond instantly to ...
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1answer
49 views

Heinner OMX-600 blender motor not turning

I have this blender that won't spin when switched on, the leds turn on tough. I managed to take it apart:https://imgur.com/a/eMSSXm4 From the mains power (!caution is used all times!) we have: on ...
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1answer
51 views

Quantitative analysis of capacitive pickup of 60 Hz by an oscilloscope probe

I was recently looking at a couple of Q&A's on this site for a description of capacitive pickup of 60 Hz by an oscilloscope probe: My scope detects a 50Hz signal when the probe is not connected ...
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23 views

EMF radiation from an open AC circuit

When I pass my EMF radiation meter near an electricity cable (a cable that is connected to the home mains), it shows me that there is a radiation. But if there is an extension cable for example, and ...

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