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Questions tagged [ac]

AC stands for Alternating Current. It usually applies to voltages with >100 V RMS, but can also be used for other AC voltages, like 24 V industrial AC power.

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Applying Ohm's law to household AC

I am a hobbyist trying to select an appropriate relay to control the heating profile of a DIY coffee roaster. For years, I have been varying the heating duty cycle by manually turning the heat OFF/ON. ...
couldabin's user avatar
0 votes
1 answer
98 views

AC dimmer / ESP32-Wroom32d

I am making Leading Edge AC dimmer with ESP32-Wroom32d. I have problem with esp timer intterupts. So I want to create a delay after zero-crossing(z.c.) (7ms) and then turn on Ac Pump and leave it on ...
Matej Knific's user avatar
1 vote
3 answers
1k views

How do PCB trace width calculators work? Why is it asking me to input the width of it?

I need to calculate the minimum trace width on my PCB for around 25 amperes (a few steppers.) When I go to a calculator, it asks me for its thickness. Here's one from Digikey, and another from 4pcb. ...
Mito's user avatar
  • 63
0 votes
1 answer
91 views

Can I use solder terminals on a PCB to power multiple AC devices?

What's the most practical way to merge multiple AC Devices into one single cable? I thought aboit it, and what if I solder multiple screw terminals on a PCB, fix them tight, attach a 50A AC fuse for ...
Mito's user avatar
  • 63
0 votes
1 answer
64 views

Why is the power factor neglected in the transformer equation?

The transformer equation is VpIp = VsIs (p is primary and s is secondary). Why is it not VsIscos(φ1) = VpIpcos(φ2)? Why do we neglect the power factor in both cases, is it equal to 1? I know input ...
Aayush Srivastava's user avatar
2 votes
0 answers
198 views

Trying to perform transient frequency response with LTspice or Microcap, TL494 compensation

I have tried to do Bode plot of my uncompensated plant by myself in LTspice 17.1, but the result looks strange to me. This topic is a follow-on to this one.. I have no clue why it comes with 290 ...
MacIntoshCZ's user avatar
1 vote
2 answers
108 views

How to measure the peak region of an AC voltage using an ADC

I am wanting to measure JUST the peak voltage region of an AC waveform i.e. like the top 20 volts of a 130 volt 100kHz waveform. I want to limit the measurement to just the peak region so that I can ...
Vernon's user avatar
  • 33
1 vote
0 answers
45 views

AC Current Sensing LED indicator circuit

I'm playing around with a circuit to drive a LED based on the output from a current sensing transformer. The idea is to have the LED appear proportionally brighter with the output from the current ...
CatalinM's user avatar
  • 387
6 votes
2 answers
382 views

What is this device on an electrical pole?

I see this setup all over my neighborhood and am curious about one of the components. The houses on the outer edge of the neighborhood seem to get their electricity by tapping into one of the phases ...
amazonprime's user avatar
0 votes
1 answer
58 views

AC polarity detection circuitry

The three wires in a marinr 120 VAC shore-power circuit are normally black for power, white for neutral, and green for ground. I’m searching for a circuit that will power an idiot-light in order to ...
brent chalmers's user avatar
0 votes
2 answers
407 views

I have 208 V, three-phase. How do I get single-phase 208 V or 240 V?

If 208 V three phase is constructed of three 120 V lines, what is the most simple and safe way to get either 208 V, single phase, or 240 V, single phase?
Erric DiFilippo's user avatar
1 vote
1 answer
77 views

Find the voltage and the current of the circuit

Can you help me to check if the results of the following circuit are right? The exercise asks: find the \$V_{3}(t)\$ and \$I_{3}(t)\$ having \$V_{2}(t)= \cos(2t + 165^\circ)\$ and \$I_{5}(t)=2\sin(2t -...
user3576105's user avatar
2 votes
1 answer
164 views

Can you help me find the datasheet of this IC marked LD5762WGR 2130DY?

This IC is a used IC on a power board. Can you help me find the datasheet?
muhammed hayr's user avatar
1 vote
1 answer
51 views

EL1018 does anyone know what it is?

Does anyone know what this product is?
muhammed hayr's user avatar
5 votes
2 answers
1k views

AC coupling to center an oscillating waveform to 0V doesn't work

I have a simple sawtooth oscillating circuit that I would like to center to 0V (remove the DC component.) I have tried AC coupling but the output is still a little to high and not centered. Could ...
Charles Guilbault's user avatar
0 votes
0 answers
73 views

What resistor is this?

I'm trying to repair a BH04221 disco LED. The resistors to AC are broken, but I don't know what kind of resistors they are. Can you help me?
Juan José Ortega's user avatar
0 votes
1 answer
79 views

Unsure how the current is traveling in the circuit. Maybe a short?

Background: I'm having some difficulties with the washing machine (WD80J6410AW/EU) UK It's blown the line-in PCB fuse on two separate main PCBs. I got a replacement PCB when it first stopped working, ...
JamesWilliams's user avatar
3 votes
2 answers
99 views

What's causing this old AC motor to behave like this?

I inherited a very old drill press from my father (120V single-phase motor). I don't use it a lot but it's always worked OK. Recently, however, it sometimes won't turn on. If I keep flipping the ...
Rob Lewis's user avatar
  • 289
0 votes
0 answers
42 views

Finding the value of supply voltage in this RLC circuit

We need to find the value of V, Power Factor, and Power Absorbed in the circuit. I am stuck at resolving the two parallel branches. I started out by labeling the impedances of the three given ...
Doodoo28's user avatar
0 votes
1 answer
47 views

Does a transformer have different primary and secondary PFs?

I tried connecting two energy meters on primary and secondary and found that they were showing different values when a load was connected to the transformer. Does a transformer have two different PFs, ...
Yogie's user avatar
  • 39
1 vote
2 answers
94 views

High voltage multiplier attempt - low voltage output

I have built a 15 stage voltage multiplier in hopes of multiplying an input voltage of 2kV to ~70kV. This voltage multiplier has been constructed with 3kV 1nF ceramic capacitors and diodes rated at ...
import_hill's user avatar
0 votes
2 answers
131 views

Why do we need AC to charge our mobile phones? [closed]

I had been wondering why do we need AC to charge our phones and not DC? Can someone please give me a detailed answer for this?
Frozen God 's user avatar
0 votes
1 answer
124 views

Feeding an antenna with DC or AC

Below is a picture with what I have done so far. It gives me a square wave with a voltage between -2.5 V and 2.5 V. Is this enough to feed an antenna so that it works? Would feeding the antenna with ...
lastime's user avatar
  • 81
0 votes
0 answers
86 views

Frequency-independent way to determine AC mains RMS voltage

I'm looking for a circuit to determine the RMS voltage of the AC mains supply regardless of its frequency. The monitoring circuit needs to be isolated from the AC mains, and I can't use a transformer. ...
bdmcnamara's user avatar
-1 votes
1 answer
53 views

Some input/help on this circuit - Looking for advice on various aspects

Design goals: I have a 9VAC (1A) power supply. I want to power some microprocessor boards with this, as well as monitor it's signal. (the whole scope is larger, but this portion is isolated to the ...
jgauthier's user avatar
2 votes
1 answer
83 views

What are the transistors for in this half-bridge non-isolated supply?

This circuit is to drive MOSFETs connected to mains using optocouplers that are not in the schematic. I don't understand the transistor usage. What are they here for? There is a version with only one ...
0x3333's user avatar
  • 229
1 vote
2 answers
74 views

AC current limiting for testing an AC circuit

I am planning to test an AC circuit which I am repairing (the circuit has a short). I want to slowly bring the power up to identify which component is shorting. I purchased a Variac, so that I can ...
Nick Bolton's user avatar
  • 2,023
0 votes
2 answers
205 views

Peak detector circuit for AC RMS value

The peak detector circuit based on a precision rectifier with buffer allows to obtain the peak value. The RMS value in an AC circuit is obtained from: RMS = V peak / sqrt (2) = V peak * 0.7071 AC ...
philfs's user avatar
  • 63
4 votes
1 answer
143 views

How do I select a replacement ICL NTC thermistor for a PSU?

I want to replace an ICL (inrush current limiting) NTC thermistor in a vintage computer PSU (for Amiga 1200). This question is similar to 'Selecting an NTC for inrush current limiting', except that ...
Nick Bolton's user avatar
  • 2,023
1 vote
1 answer
81 views

Can I use an Arduino for controlling MOSFET transistors to make a pure sine wave AC power inverter?

Modern AC invertors use controllers to turn on/off transistors to generate PWM pulses that will become a pure sine after filtering. Is it possible to use an Arduino as that controller? What cheap ...
Robotex's user avatar
  • 153
4 votes
5 answers
1k views

How to power a 24 VAC pump with 24 VDC?

I want to power a 24 VAC vibration pump (48 W 50/60 Hz, often used in coffee machines), and control it with a microcontroller. I've got an existing system that is powered with 24 VDC. A standard DC-DC ...
empewoow's user avatar
0 votes
0 answers
83 views

DC circuit works well and AC does not

I have the following circuit that consists of a power supply that, despite the redundancy, powers a 12V lamp and an arduino with 4 solid state relays. I do the tests with a direct current laboratory ...
Lucas Daligo 77's user avatar
2 votes
3 answers
132 views

Can we connect multiple devices to the mains with just 1 cable?

The project: An Arduino DIY Relay-controlled aquarium with a water pump, a heater, and a light bulb. All 3 have the exact same wires according to the EU standards: 1 "hot" brown wire and a ...
Mito's user avatar
  • 63
1 vote
1 answer
55 views

AC voltage and frequency measurement

I am planning to measure the AC voltage from a 3-Phase ranging 480V/690V effective value with almost 10-20% tolerance => a max. peak of around 1171V. I try to use protective impedance to step down ...
Rompel's user avatar
  • 11
0 votes
0 answers
34 views

Infrared beam: AC or DC power supply on the same pins

I have an LA5179 infrared beam from JAYCAR. The manual says it has 2 pins which allow for "12 to 250 VAC or DC". The 2 pins allow for the + or - to be on either pin for 12 VDC. The same 2 ...
clarke's user avatar
  • 1
0 votes
0 answers
38 views

Measuring AC current with Raspberry Pi Pico [duplicate]

I need to measure the voltage from a current transformer with a Raspberry Pi Pico, but it outputs both positive and negative voltages, so I need to offset it. Can anyone recommend me a simple op-amp ...
Arduino's user avatar
1 vote
0 answers
45 views

Difference in amperage at the plug vs at the source (three-phase wye, 120 V and 208 V loads)

I'm trying to understand the difference between how my work calculates power at the load vs how we calculate the sum at the source. We run temporary power and plug in several hundred industrial ...
Phsion's user avatar
  • 11
0 votes
2 answers
91 views

In superposition theorem, can I activate multiple sources together?

I was doing AC circuit analysis using the superposition theorem, which as far as I understand means I can add up the effects of multiple sources by activating only one source at a time (to simplify ...
Shams M.Monem's user avatar
2 votes
2 answers
201 views

Can I see a schematic for a 110 <-> 220 V power converter?

I would like to see a schematic for those 110 <-> 220 V power conversion transformers-in-a-box. I've read they are autotransformers (one winding with multiple taps). I'm using one to step up 110 ...
Rob Lewis's user avatar
  • 289
0 votes
1 answer
54 views

Recommendation for 5 V, >2.5 A supply brick with 2.1 mm barrel jack (center positive) power supply

I purchased an AWR1843BOOST automotive radar sensor evaluation module. The power supply must be purchased separately. The specifications say I need a 5 V, >2.5 A supply brick with a 2.1 mm barrel ...
Pankaj Sejwal's user avatar
0 votes
1 answer
114 views

Is a standard AC/DC USB power supply galvanically isolated?

I've definitely seen some sketchy, super low-cost DC devices which plug into the wall and have no galvanic isolation (think $5 WiFi-enabled smart plugs from Target,) but those devices don't have wires ...
Kenn Sebesta's user avatar
0 votes
2 answers
119 views

Algorithm for impedance calculation from known I and V sinusoids, L and C unknown

I am trying to extract the impedance from a sampled signal. Specifically, I have only noisy samples of a sinusoid, of a single period, of current and voltage at a given known frequency. I am trying to ...
thexeno's user avatar
  • 1,290
1 vote
1 answer
88 views

DIY voltmeter safety concerns

I would like to build a voltmeter using an ATMEGA328P that measures AC mains voltage. I came across the following schematic which appears to be what I am looking for: The top part of the circuit goes ...
jhorv's user avatar
  • 85
1 vote
0 answers
75 views

Winding coils in an AC generator

Assume a coil arrangement in an AC generator like the one seen below: Given that the magnet has one pole on each side (2 poles in total in the magnet), how must the surrounding coils be wound? In ...
Manuel's user avatar
  • 11
2 votes
1 answer
109 views

Mains AC detection circuit - will it work?

I´m trying to detect mains voltage (230 VAC) across AC_SENS_L and AC_SENS_N. AC_SENS_IN goes to an Arduino input with pull-up. I only need to detect if voltage is present, not what voltage. Any ...
VLKRT's user avatar
  • 53
3 votes
7 answers
477 views

Why does a capacitor connected to AC and high impedance act as wire?

Given this figure: simulate this circuit – Schematic created using CircuitLab I observe that Out is mirroring what's on the left side of the capacitor, effectively becoming a wire. I know that ...
user avatar
0 votes
2 answers
132 views

Can series capacitors reduce guitar cable capacitance without signal loss?

Recently, I was reading about a so-called zero capacitance guitar cable pitched to eliminate resonant frequency shifts when using higher impedance passive guitar pickups. The company claims their ...
doktar rico's user avatar
0 votes
1 answer
52 views

Need sort of 'one-way AC relay' for connecting two L-OUT sources to feed a single L-IN destination

I need an AC analog of what in DC world would be 1 x relay and 2 x one-way diodes. To clarify what I am doing: I am going to have a heating pump (...
Alex Smirnoff's user avatar
0 votes
0 answers
155 views

AC voltage measurement with an op-amp

I want to know if there is a problem with the circuit of the picture, I need to measure 120 VAC. In this example, there are not isolation and I don't want to fry my PC. Any tip? The output of the op-...
Francisco José Pantoja Zapata's user avatar
2 votes
2 answers
161 views

What is the correct relationship between active, reactive and apparent power in non-linear AC systems?

I am somewhat troubled by the 'basic' formula that describes the relationship between apparent power (S), active power (P) and reactive power (Q) in AC systems. This formula is ...
JeromeBu1982's user avatar

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