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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AC voltage regulator in parallel

I have two voltage regulator which works on ac. They are both the same model and provide a maximum power of 3000w. I would like to plug their outputs together to make a 6000w total voltage regulator. ...
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28 views

AC equivalent circuit -BJT

For the following circuit, I'm asked to give the AC equivalent circuit for small alternative signals. On the second circuit (the one they gave us as a solution), I don't understand why they didn't ...
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73 views

Circuit for voltage division and DC shift doesn't work

I've connected the circuit below on a breadboard and tested it in the lab: Components: ...
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1answer
43 views

Common Emitter amplifier Bias Circuit Simplification

This is a slide from one of my semiconductor devices lectures. I understand how the bias circuit works and how to calculate the resistor values however I do not understand how this simplification ...
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0answers
28 views

Artificial Lightning [on hold]

I am planning to create artificial lightning from home electricity (240V AC).In order to do that I need to have two balls, one with positive and one with negative charge with high potential difference ...
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2answers
38 views

finding the sinusoidal values of a complex current or voltage

I am having some trouble understanding this type of transformation. The materials provided by my professor doesn't even mention the method that is being used to switch from complex to sinusoidal and ...
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2answers
54 views

Do devices on AC currents have flicker on and off?

For current to alternate between positive and negative it must be zero for a split second. Does that mean devices receiving AC current are flickering on and off? This seems like it would have some bad ...
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1answer
64 views

Need advices on an AC fan control circuit

I've setup a small system where I can control an AC Fan by a data-acquisition board's DAC. Here is my final schematics(please left-click to enlarge it): The first issue was to hack the manual speed ...
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1answer
28 views

Questions about a relay controlled AC fan setup

I need to switch an AC fan by a DAQ board's analog output. Here is the setup in my mind for the moment: The DAC of the data-acquisiton board can output 0 to 10V DC and can deliver max 5mA current. ...
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0answers
21 views

Feedback on an AC power measurement design

Here is an AC mains power measurement schematic that I tweaked from one of TI's smartplug designs. This simulates well in LTSpice and I was hoping you could give feedback on this. What improvements ...
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1answer
37 views

AC power measurement query

I'm trying to understand and tweak this smartplug reference design from TI. I'm stumped on the Metrology Analog Filters section on page 1. What I do not understand is why is there a 0R resistor on the ...
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1answer
39 views

Power supply - Boost voltage over distances

I'm looking for a good power supply design to boost the DC voltage and convert it to AC so it can be transported over a long distances with low loss. I have drawed a example picture: The only thing ...
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3answers
42 views

AC motor control

I have a simple AC motor, a pump. There is no kind of regulator in terms of speed or pressure. Its supply is 230 Vac, 50 Hz. If I decide to lower its supply voltage, what happens? it will require ...
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2answers
95 views

Why this circuit has a DC current?

Consider the circuit below: simulate this circuit – Schematic created using CircuitLab If I try to solve this circuit in the frequency domain, I get: $$X_C = \frac{1}{\omega C} = ...
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2answers
81 views

What kind of generator do i need to run a 1.5 or 2 ton Air Conditioner? [closed]

I am planning to purchase a single AC that would operate on my Diesel generator. My Generator is a 5kVA , 8 HP air cooled one. I want to know that If I have to run only one AC on the generator shall I ...
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1answer
27 views

AC circuit to act as a relay for another DC circuit

In this circuit, I have caused an AC current to power the gate pin of the Thyristor, which in turn should allow the 10v DC current to pass even after the AC current inverses - it is not a ...
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2answers
40 views

What would happen if we supply dc as well as ac voltage in a circuit? [closed]

How the characteristics of the circuit will change if we supply some dc voltage in an ac circuit ?
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3answers
485 views

Why a neon lamp indicator on power strip switch flickers in the dark?

Neon lamp indicators embedded in power strip switches indicate whether the switch is ON or OFF. When the neon lamp is ON in a dark environment (lights of the room are off) the lamp start to ...
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1answer
29 views

AC Line detection using MID400

I want to detect an AC Line Voltage (230V RMS, 50 Hz) and interface it with a microcontroller. I am aware about two solutions. Using an optocoupler like PC817 [datasheet] using MID400 ...
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1answer
107 views

Controlling a single phase AC fan with a 0-10V DC input

I have a fan motor which is a permanent split phase single phase capacitor motor: http://uk.rs-online.com/web/p/axial-fans/2781543/ I currently control this fan's speed with the following ...
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2answers
39 views

Purely Capacitive AC - voltage and current relationship

Studying electronics, capacitors in AC circuits currently. Can not understand two formula's. I see it stated as fact: "In purely capacitive AC circuit Current leads Voltage by 90 degrees." I ...
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1answer
28 views

AC Analog Isolation

Please excuse my limited knowledge of electronics, my problem is I've a circuit which is driven by a variable AC signal using LabVIEW it ranges from 100Hz to 100kHz (I can lower this to 30-50kHz if ...
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4answers
317 views

How safe is a current transformer

I acknowledge that the subject line indicates a "how long is a piece of string" style question, but I hope to make it more specific below. I have a "current transformer" (CT) purchased as part of an ...
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2answers
30 views

How to Series Wire Secondaries of a Multi Winding Transformer?

If I have a transformer that has 3 low voltage secondary coils (3V, 6V, 12V) and 1 primary coil (120V), how can I wire 2 secondaries in series? Can you show a diagram with a load? Is there such thing ...
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1answer
42 views

Switching circuit or relay [closed]

I'm new here and don't know much more about electronics.I need a switch/relay that help me off DC line when AC (grid) line is available and automatically turn on when AC (grid) line is not available. ...
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4answers
358 views

Can a Transformer Have Multiple Secondary Coils?

Can a transformer have multiple, isolated, secondary coils from a single primary coil? Can each coil have a different voltage from the other? If so, is there any large negative effect, and what is the ...
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2answers
83 views

AC/DC optocoupler wiring

Looking for some clarification on the proper wiring of an AC/DC optocoupler (HCPL3700, datasheet) when working with 120vac. From what i read online it looks like a need a resistor on the hot side ...
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1answer
103 views

LED light dimming, TRIAC vs PWM?

Many days ago, I published a question here asking about dimming an AC LED using and Arduino and TRIAC, and I was told that most LEDs that support dimming should work with the circuit I linked to them. ...
0
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1answer
34 views

Current Transformer properties

I have a mains track (230VAC, 50Hz) on a custom PCB routed to multiple Solid-State Relays, and I want to measure the power going through this line. I'm looking into Current Transformers (CTs) to ...
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4answers
75 views

Why doesn't positive/negative terminal matter in some electrical applicances?

I was wondering why, in some electrical appliances, it doesn't matter which terminal is positive and which is negative, the applicance works anyway. They have plugs like this: An example, the ...
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2answers
97 views

Synchronizing a diesel generator with a pure sine wave inverter

As the title reads, I'm trying to understand the best (Practical) way to synchronize a diesel generator with a pure sine wave inverter, in order to implement an automatic synchronizer based on ...
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3answers
67 views

Assume AC Phase has zero potential

The neutral null wire is said to have potential 0 while the phase wire has a varying potential. It seems that the potential 0 for ground or null wire is just a definition. One can define its potential ...
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2answers
66 views

2 NO reed switch - turn on 230V water heater

For a small home project I would like to turn on a water heater using 2 NO reed switches. Once I put a small magnet ontop of the reed switch (turn the reed switch to Close), the water heater will be ...
4
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2answers
628 views

Are we close to a pure DC (or hybrid) household? [closed]

This is a philosophical question. Over the last few years, many of the household devices, particularly those that are more mobile and etc are DC devices. Are we at some point where a DC household may ...
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4answers
76 views

Converting a toy from battery to DC power adapter

My kid's bubble blowing machine runs on 8 AA batteries which it chews through in less than an hour. Also, only the first 15 minutes seem to make a satisfying amount of bubbles and after that, it fades ...
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2answers
52 views

Dimmable AC LED controlled by Arduino

I am a beginner, and I have a school project that requires me to use Arduino or any other microcontroller to control an LED light. After some research, I found out that not all LEDs support dimming, ...
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2answers
155 views

Tactics for Controlling Heat in a High Current Bridge Rectifier?

I'm having trouble controlling the heat from running a bridge rectifier (Similar to ...
5
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3answers
179 views

Why does this optocoupler circuit work without getting destroyed?

This circuit is being used for mains detection. Input is being fed directly from 220V 50Hz mains and output goes to Arduino which is running on 3.3V. Theoretically the optocoupler LED should burn out ...
3
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2answers
175 views

Differences Between Smoothed DC & Not Smoothed DC With Respect to Heating

Are there any significant differences with respect to heat generation of a bridge rectified circuit with smoothed DC by use of a capacitor vs one that just uses the raw absolute value of the sine ...
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0answers
24 views

230 VAC signal with spark capacitor should work on a high-impedance sensor

Preface There are lot of a motion sensors which turns on L (phase) on its output. In my case I need to connect this output to my board to 'sense' the motion. To do this I put 1 MOhm resistor between ...
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3answers
138 views

Wire the green ac earth wire in wooden chassis?

My own power supply is just about finished. Since i live in Europe the voltage here is 230v, from that it goes into my step down transformer that steps down the voltage to around 20 V AC and then into ...
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3answers
89 views

Using the neutral instead of the earth to supply electrons

I'm working on a VAN DE GRAAFF generator and I need to connect the bottom comb to the earth ground. But in my country we do not have a ground line . Can i use the neutral line instead and connect the ...
1
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2answers
59 views

Electrical current characteristics through conductor

This is a strange theoretical question, and I won't even begin to try to explain what train of thought has led me to ask the EEs... When electricity travels through a conductor, let's use the obvious ...
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2answers
53 views

Which oscilloscopes can reliably measure losses in an inverter for an AC motor?

For my next project at my workplace I am looking for an oscilloscope which gives me good support in measuring the losses in one of the half-bridge switches over one commutation period. The last time I ...
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4answers
595 views

Why did my oscilloscope hookup trip my RCD?

I was attempting to investigate an SPI interface on a power line meter (typical model that measures Voltage, Frequency, Amps, Watts). I opened the module and found the SPI pins broken out. So I ...
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1answer
124 views

Can I give DC 12V to a AC 12V input?

I have a circuit that takes 12V AC as an input but my bench power supply only delivers 12V DC, is there any issue if I give the device DC instead of AC? (Same voltage) Straight after the input there ...
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1answer
90 views

Reason for High voltage difference between Ground and neutral wire in 3 phase system

I have following reading of voltages: RY 397V RB 398V YB 393V RN 231V YN 227V BN 228V RG 386V * YG 385V * BG 10V * NG 216V * If you clearly observe data above phase-to-phase voltages ...
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2answers
59 views

Live wire in square wave inverter

I have a square wave inverter, as you can see in following pic when i test live wire in square wave inverter, both output wires appeared as live wire but my pure sine UPS have only one live wire, why? ...
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1answer
113 views

Best way to convert 5V DC to 110V AC at 50Hz for pdlc film drawing 2mA max. Size is the thing!

I'm working on a project in which I'm hoping to integrate several small segments of pdlc film, which starts off diffuse white/'frosted', turns clear when excited with 110V AC at 50Hz and is apparently ...
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2answers
3k views

Does a DC toy motor emit AC when you spin it?

I just watched a video on Facebook by somebody who built a project to run an LED using a 9 volt DC motor scrounged from a battery operated toy. They simply wired the LED to the motor and then used a ...