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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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How do non contact voltage detectors work on open circuits

I’ve seen how people use non contact voltage detectors to check whether or not a socket’s live wire has power. Non contact voltage detectors take advantage of capacitive coupling that occurs in AC in ...
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3answers
43 views

Convert Battery to AC @ same voltage

I have some LED fair lights that run on 30V @ 0.4A supplied from an AC mains supply. They have been wired to flash using some form of notification to the AC (I'm not interested in them flashing). I ...
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45 views

DC or AC electric motor? [on hold]

Which is better for Electrical Vehicle conversion? An AC electrical motor or a DC electrical motor? And why?
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138 views

LEDs in household outlet

The output of the household outlet is AC. But when repairing one of those, I found that there was a LED (used as indicator) in there. Since LED is a diode, it must switch on 60 times and switch off 60 ...
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1answer
81 views

How to extract energy from an alternating electric field?

Given an alternating electric field E inside e.g. a big parallel plates capacitor, how can you make use of the field's energy to power an electronic device? So far I thought of putting two smaller ...
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1answer
45 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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3answers
70 views

AC coupling capacitor in the ground to break the ground loop?

I'm implementing the following audio single-ended to differential converter for an ADC: This is the reference design for the PCM1804 that I intend to use. What would happen if I do this: Would it ...
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1answer
29 views

If I use a CAT 2 10x probe does my DSO need to be CAT 2?

I need to measure the harmonic distortion on a solar inverter (power output). I need to buy all the equipment from scratch and was wondering if my DSO needs to be CAT 2 rated if I use a CAT2 10x probe....
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2answers
52 views

Filter harmonics in AC power line [on hold]

I run a Toshiba Digital copier machine in my shop and the machine started showing error codes related to power issues a few days ago. This happens randomly during daytime. There were no problems at ...
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2answers
52 views

Output voltage of a rectifier

Is the output DC voltage of any rectifier (Halfwave, Fullwave or bridge) simply equal to \$\sqrt{2}\$ times Phase to neutral AC input voltage? Or does every rectifier circuit have its own formula to ...
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1answer
595 views

Does resistor power rating mean 'real' power?

Given a mixed capacitive-resistive circuit, I have a \$36 \Omega\$ resistor through which a current of \$9.22 \angle 86° \text{mA}\$ passes. My AC theory is rusty, but wouldn't I do: \$P = I^2 R = 3....
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1answer
31 views

Series R-L AC Circuit Analysis - Conditional

Is there a way to get resistance and inductance of a circuit wherein the only given is the source,circuit current and its frequency? To make it clear, ill give an example: An impedance coil takes a ...
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1answer
72 views

What type of current is used by a transmitter? [closed]

(Short question , No need to downvote): What is the required current type in a RF transmitter (AC or DC). Since Phones have a battery (hence DC) how do they power their transmitter if AC is required?
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1answer
59 views

How to increase low voltages modified AC Sine wave up to 220 VAC with 0.25 Watt?

I am working on Multilevel Inverter and successfully achieved modified sine wave with 7 level, that is much better according to my requirement. But the problem is output AC voltages is too low which ...
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4answers
2k views

Just how accurate is the frequency of US Wall Outlets? [duplicate]

I have a submersible pump for which I'm trying to determine the variability in flow rate, to high precision. Since this is just an impeller driven by an AC motor, what is the % error in frequency of a ...
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4answers
133 views

Is this line detector safe?

I'm thinking about building a basic AC mains voltage detector. I'd like for it to be both protected and isolated, so I have a zener TVS and an optoisolator. R1 and R3 are chosen so that between them,...
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2answers
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AC Circuits: Determine the RMS current in the Inductor in the circuit diagram attached below. (Voltage is 40V, RMS)

Here is the image of the circuit diagram. I wanted to know the method to evaluate the RMS current in the inductor branch. I would prefer to use complex analysis!
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51 views

digital electricity meter

I have a three phase digital electricity meter. It sends a data-packet/info, every 15 min, which I can read and log the data. This data packet contains some relevant info. to calculate energy usage. ...
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1answer
51 views

AC input not matching DC output

I know this might sound stupid but it has me stumped. I am trying to calculate the average AC power input required for a few electrical devices which will be connected to a generator. The issue I'm ...
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2answers
854 views

Having trouble in GPIO output, 220 V to 5 V signal

I'm not an electric guy, I'm just trying to build a small circuit to sense 220 V with my Microcontroller (RPi). But I'm getting either 5 V or 1.3 V on a GPIO wire. I can't understand the problem. I ...
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2answers
56 views

24-0-24 Rectified DC Circuit

I've been attempting to build my first lab power supply, I have my components, and have studied many circuit diagrams. I thought my knowledge was good enough, however I'm now at an impass. I have a 24-...
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1answer
48 views

Decreasing the surge power of the AC loads

I have a pure sine wave inverter 12v to 220v AC, its continues output power is 600VA and the surge power is 1130VA, I want to running my 200W fridge, but unfortunately my fridge surge power is a bit ...
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13answers
9k views

Why do fundamental circuit laws break down at high frequency AC?

We're just starting the whole RF scene having dealt with DC and low frequency AC for all our previous courses. I understand that at high frequency AC, fundamental circuit laws don't apply anymore ...
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1answer
64 views

How to prevent a low duty cycle load from flickering lights

This is a follow up question to this: Alternatives to Large Transformer or PSU for Driving DC Heater I've hooked up 120v AC to a zero crossing SSR and a 3.2 ohm resistive load. To get my desired ...
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2answers
147 views

Is there any way to convert 50 Hz directly to 1 MHz? [closed]

I want to know whether there are any ways to convert 50 Hz AC to 1 MHz without Voltage Controlled Oscillators? If I'm correct, all the normal circuits convert the AC to DC and then use it to ...
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2answers
362 views

Why is the Active/Real Power Rating So Low for This Relay?

I'm trying to select a relay for a IoT project that will control a water boiler. I took a look at the HF32F-G relay, but some of the specifications in the datasheet weren't making any sense to me. ...
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2answers
48 views

Meggering Three Phase Motor (Phase-GND, Phase-Neutral, GND-Neutral)

When meggering a three phase motor, could someone please help me understand the values we would expect to see for a motor with no insulation or ground faults. From my understanding: Phase-GND: ...
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1answer
48 views

Can 3 phase AC current be applied to a BLDC and vise versa?

I am just wondering because the designs of a synchronous motor and BLDC are the same. Could you please explain the downsides of not using the designated current?
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1answer
77 views

What motor do i use to rotate a tumbler at low RPM and high torque which run by a battery charged by solar?

I am gonna run the motor to turn a tumbler of 50-85 kg @ 5 rpm MAX. The motor will be powered by a battery which will be charged by solar. So should i go for a DC or AC motor? Single phase or 3 ...
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1answer
118 views

Instantaneous vector sum of three phases 120 apart is not zero?

Vector sum of equal 3 phases 120 degree apart is zero and serves as a neutral. However, while drawing instantaneous vectors of the three phases, they summed up all together to give a vector. I have ...
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2answers
49 views

Alternatives to Large Transformer or PSU for Driving DC Heater

I have a 3D printer heated bed, instead of 3d printing I want to use it for reflow soldering. The bed is intended to operate at 70c, using 12v or 24v. It can be wired in series or parallel depending ...
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1answer
63 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 ...
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1answer
49 views

Confusing phasor representation

Why capacitive impedance has the magnitude \$Z_{c} = \frac{-j}{\omega C}\$ but in the phasor diagram, we represent it as a vector pointing in the upward direction?. Same is with the case of an ...
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4answers
98 views

How to measure leakage current?

I have an AC powered device, and a customer asks for exact leakage current. Current that can trigger a leakage current circuit breaker, so it's obviously something flowing through Y capacitors to the ...
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1answer
77 views

powersupply ac to ac

I have recently bought a dcp917S and hoped I finally found a wireless chime that I can tie into my apartment buildings bell system. Since I live for rent there I can't do any changes that are not ...
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0answers
39 views

Ceramic capacitors in series to increase AC voltage rating

If I put 4 of 1uFx100V cercaps in series I will virtually have one .25uFx400V capacitor. As I know I should use balancing resistors for even distributinon of the voltage across the capacitors. ...
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2answers
113 views

Do resistors consume reactive power?

I encountered this problem in one of my books where the problem asked to find the power loss in the core of an induction motor. I worked through the problem and I found the current as in the picture, ...
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1answer
62 views

Care to be taken while connecting 220 VAC to MCU pin

I have a product with a non isolated power supply which has 220 VAC live line as the GND reference: My MCU receives 3.3 VDC from the same circuit. I want to detect the presence of 220 VAC (same ...
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1answer
61 views

What is the main difference between AC and DC generator basic working principles? [closed]

I cannot understand the main difference on AC- DC generator basic working principles. Lets consider how a loop wire works with a magnetic flux inside a DC generator briefly. Whenever the sides of the ...
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3answers
220 views

What is generic formula for min and max levels of rectified AC voltage?

For example, if i have 1 phase AC voltage with 1 volt peak level and rectify it., i would get some pulsating voltage V = abs(sin(t+0*pi)). Its minimum is 0 volts ...
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1answer
53 views

How do I identify a what kind of power connector for AC mains is on a product?

I see an AC mains input but I have no idea what kind of cable it goes to, how do I find the cable type so I can design around that? (Or conversely I have a cable and I doubt know what type it is)
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2answers
55 views

What makes an alternating-current electric motor rotate in a preferred direction?

Intuitively, from a position of ignorance about the design of AC motors, I would have expected the direction of rotation to vary randomly with each start-up. This appears to be the case for motors ...
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2answers
63 views

Simple phasor problem with AC

Simple problem that I can't solve. On this AC circuit, find the current read by ammeter \$ A_3 \$ (the one in series with the resistor) given that \$A_1\$ reads 4A and \$A_2\$ reads 3A, assuming ...
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1answer
63 views

Switch that turns one lamp on while keeping the other one off - Mystery

We tried to connect outside light bulp (AC) to a switch where an another light bulb is already connected. We did a parallel connection. Roughly like in the schematic. (I'm not an engineer so the ...
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3answers
139 views

Can I touch voltage?

After watched this man this man, I have some questions. He touched 170 VDC, what is max DC voltage can I touch when I dry? And wet? What is max AC voltage can I touch when I dry? And wet? Is ...
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1answer
69 views

Why use RMS instead of the average voltage of half the cycle for power

In a AC sine wave, the RMS voltage value is \$\frac{V_{p}}{\sqrt{2}}\$ where \$V_{p}\$ is the peak voltage whereas the average voltage value over half the cycle is \$V_{p}\cdot \frac{2}{\pi}\$ If we ...
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3answers
45 views

Power meter current transformer: possible to sum mutiple phases

I am currently looking at this inexpensive power meter modules with TTL interface. It seems to use internally the same ASIC as many chinese wall-wart power meters: It comes with a current transformer ...
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2answers
68 views

Can I safely connect batteries to an AC-powered device? [closed]

Let’s say I have a device, and on the box that goes into the wall it says “9V DC.” If I understand correctly, this means that it modulates the electricity coming in from the wall so that the appliance ...
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1answer
39 views

Series RL AC circuit Laplace analysis

Question: Find the complete expression for i(t) in a series RL circuit with source \$Vsin(\omega t)\$. simulate this circuit – Schematic created using CircuitLab So to attack this I thought to ...
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0answers
73 views

Removing DC from signal

I am using the MAX30102 sensor to calculate blood oxygen concentration and I am trying to understand an algorithm I found. Some background on SpO2:https://www.nxp.com/docs/en/application-note/AN4327....