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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11
votes
1answer
267 views

Is this LED fixture safe for use with its current fabrication?

My father is currently interested in investing into a Ukrainian LED fixture manufacturer, and after he bought home a sample, I'm scared. There are 94 LEDs paired up with diodes, all in series, ...
9
votes
2answers
43k views

how does the circuit of a basic Variable speed electric drill work?

i am trying to 'automate' the control of an electric drill motor that im taking from a garden variety Variable Speed drill (from Harbor Freight) it has a universal AC motor which I basically ...
8
votes
3answers
3k views

Is it okay to connect a European 240V transformer to a US 240V outlet?

I've an old Bosch German made automotive charger transformer with ratings 14V/9V, 220-250V @ 50/60Hz 132VA. Can I use it on the 220 to 240V outlet here in the US which uses a split - phase system as ...
7
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2answers
70k views

Converting Power/Watts in DC to Power/Watts in AC?

How can we convert Watts in DC to Watts in AC? for e.g A device needs 1A and 12V DC input i.e (1A x 12V = 12 Watts) 12 Watts DC. If we use an AC to DC adapter/converter to generate 1A,12V (12Watts) DC ...
6
votes
3answers
9k views

Why is high voltage AC more common than high voltage DC?

Why is that high voltage AC is more commonly found than High voltage DC? Example my battery powered fly swatter and fluorescent lamp both use high voltage AC. Why can't these devices increase the DC ...
5
votes
3answers
4k views

How is the 220V line in US different from other parts of world? Does a US 220V line need two switches for each wire?

Today my A/C compressor had given up its ghost and when I tried to disconnect it from the wall switch after turning OFF the wall circuit-breaker,I assumed like most 110V lines where only one line (...
5
votes
1answer
503 views

What is the name for PCB mount AC power connectors

What is the search keyword for PCB mount AC power connectors? I'm looking for just the metal connectors (plug and receptacle) for solder to the PCB. I'm asking for the brass connectors shown above. "...
5
votes
4answers
2k views

Push Button with Voltage Rating (AC) : 125V, Only having power supply of 3.5 or 5V

I have 3 buttons (R13-81 PUSH SWITCH) for a school project. In the specifications, it is written that they take Voltage Rating (AC) : 125V (Source) Problem is I only have 3.3V or 5V as power supplies....
4
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2answers
3k views

How to measure AC voltage without a voltage divider using microcontroller

I have to measure AC voltage of the mains supply 180-220 VAC through a microcontroller. I have been wondering how to measure it without using a voltage divider. Since the resistance may wear out with ...
3
votes
3answers
13k views

Trouble with triac driven dimmer circuit

I have a dimmer circuit that produces the following wave forms. Red: Triac Gate Signal Yellow: 120v 60Hz AC Wave (not triac output) I would assume that given this signal, the triac should flip on ...
3
votes
6answers
9k views

How to design a AC current detection switch?

I am working on a home automation system and I need to detect if a appliance is getting power or not. Basically, I need a AC current detection switch which can be mounted on a power line and sends a ...
2
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2answers
3k views

How can I add three AC signals?

I have three light sensors which outputs appropriate AC currents with respect to light intensities. I only have one pin left for my ADC IC that I have on my board so I can't sample three sensors using ...
10
votes
8answers
101k views

What happens if a 240V appliance is connected in a 120V AC power supply?

I know that putting 240V through an appliance rated at only 120V would almost certainly damage it. But what if I connect an appliance rated for 240V into a 120V AC socket? Apart from degradation in ...
9
votes
1answer
6k views

Current limiting at mains voltage

I am driving a BTB16-600BW triac using a MOC3052 exactly as suggested in the MOC3052 datasheet: The current into the power triac gate is limited using the highlighted resistor. My triac requires at ...
8
votes
5answers
4k views

When we should use only an “Analog” multimeter?

I know electronics testing with digital multimeters is easier than analog, but I'm wondering whether there is any electronic testing which can done with only "Analog" multimeters? For example ...
7
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2answers
10k views

Transformer labeled 120v-60hz-35va-12v - What exactly does it do?

I have a pool light whose bulb physically broke, but I've found a way to open the water-tight bulb enclosure to get at the actual bulb. I'm trying to either hunt down a replacement bulb (rather than ...
5
votes
6answers
18k views

Does a circuit breaker trip depending on voltage or current?

I've have a GE 120V 20A circuit breaker. I'm aware that once it exceeds the 20A rating the breaker does its job and trips, but what happens if the current is less than 20A and the voltage lets says ...
5
votes
1answer
2k views

What is the Thévenin equivalent of the mains power supply?

Thévenin's theorem says that any voltage source can be modeled as an ideal source in series with some complex impedance. How does one quantify this model for AC mains supplies? What parameters are ...
5
votes
1answer
2k views

Why do you get shocked touching a live wire?

A number of times (over many years) I've accidentally touched a live AC mains wire (120V, 60Hz) while working on home wiring. The feeling is always similar: uncomfortable tingling feeling at the ...
4
votes
2answers
109 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 don't know what type it is)
4
votes
3answers
2k views

How does a negative current start in the inductor in ac circuit?

As shown in this image, how does a negative current appear at the beginning, when the voltage starts to increase ? I understand the current lead lag mathematics behind it. I just can't figure out, ...
3
votes
1answer
611 views

AC Power measureless using MCU, calculations problems

I'm done from the hardware design sensing the current & the voltage levels using my MCU (AVR) & some circuitry Beside I wrote the firmware to handle the ADC data & so on But I'm, having ...
3
votes
3answers
251 views

Transformer magnetizing inductance

I am learning about transformers and in the equivalent circuit the magnetizing inductance of the excitation branch is supposed to represent the current needed to "set up" the flux in the core due to ...
3
votes
2answers
1k views

What good is an induction coil in a dimmer switch?

I asked about a dimmer switch, and was told one has an induction coil. What benefit is an induction coil in a dimmer switch? ZE-02S has induction coil built-in on the circuit board, so it is 5/8" ...
3
votes
1answer
1k views

Simple AC line state detection for digital controller input

Last year I moved into a house that has an old ('50s-'70s vintage) GE low voltage lighting control system. It uses 24VAC momentary wall switches to toggle solenoid/latch relays that feed 12 main ...
3
votes
3answers
10k views

Does a resistor in an AC circuit produce the same heat as in a DC circuit?

Does a 1k ohm resistor produce the same heat in a AC circuit which has an rms voltage of 10 volts (60 hz.) as it would in a 10 volt DC circuit?
3
votes
2answers
3k views

Is it possible to change the speed of an AC motor(drill press) without losing too much torque?

I have a drill press as in the image below, it runs from 110V AC 60Hz and has internal belt reduction. Unfortunately however for some materials and hole widths, I need it to go even slower than It's ...
3
votes
4answers
30k views

What happens if an AC voltage is applied to a battery?

Today I was checking the voltage between charging terminals going to the battery of emergency lantern using a multimeter. The multimeter showed a DC voltage of 9V and an AC voltage of 4V. Could ...
3
votes
2answers
8k views

Supplying ac to a dc circuit

So a while ago, i was stumbled upon a post what will happen to the dc circuit when we supply ac to it. Lets assume the ac has the same voltage as the dc. We know that ac switches direcions so there ...
3
votes
2answers
752 views

Is it OK to have data lines and AC in the same multicore cable?

I need to provide the following over sections of 1m multicore cable, totaling around 15m. 240v AC 5v DC GND RX TX Will the AC cause problems for the Serial data?
2
votes
1answer
815 views

precise half-wave rectifier problem

I'm actually trying to build a precise full wave rectifier. But after a first failed try, I though I would better be off break down things to analyse every part of the circuit. So, I started building ...
2
votes
0answers
749 views

Why does a multimeter in resistance mode show initial continuity over a diode?

I originally phrased this question very differently; the original text is retained below in case background information is useful to clarify the context. When I using this digital multimeter to ...
1
vote
3answers
4k views

Effect of non-inverting op amp on the AC and DC components of the input

I was wondering what the effect of an op amp like the one in the image below is for an input signal such as \$0.5\sin(2000\pi t) + 0.5\$ V? Are the DC and AC components amplified with the same gain? ...
1
vote
1answer
603 views

Analog Dimmer Circuit Analysis

I am trying to analyse the basic circuit of a dimmer. I don't have much experience in AC circuits, so I am not sure how do I need to proceed. My circuit is the next: I have something like this: I ...
0
votes
3answers
93 views

Choosing capacitance for recifier

So I'm trying to use a couple of rectifiers. Specifically, the "NTE5326" and the "36MB120A." I've tried following videos on how to calculate for a smoothing-capacitor but to no avail. If you use ...
0
votes
2answers
15k views

What is the relation between the stator current and motor rpm for an AC motor?

A 3 phase AC motor is rated values are: 970 rpm, 50Hz, 380V delta 47A. A VFD drives this motor for obtaining a constant wind-speed which rpm is proportional. The thing is when 885 rpm the stator ...
-1
votes
2answers
55k views

By touching neutral why we do not get shock? [duplicate]

According to Benjamin Franklin, current flow from +ve to -ve terminal. But after Joseph Thomson's discovery it was conceived that although current flows from +ve to -ve electrons flow from -ve to +ve ...
7
votes
3answers
36k views

What is the formal definition of Quiescent Point?

What is Quiescent Point? Is it necessary for it to be related with any V vs I , I vs I, or any such characteristic curves intersection point?
7
votes
3answers
9k views

How are multiple power sources synchronized in a grid that uses a distribution ring?

A large distribution grid can work like this. There're several power station each outputting 50 Hz AC. Each power station feeds energy into a substation next to it which raises the voltage and then ...
7
votes
2answers
2k views

What keeps mains power at 60hz?

In a power plant, what keeps the power at a solid 60hz? It seems like turbines can't always be running at the exact same speeds, given that combustion doesn't always give the exact same temperature (...
5
votes
1answer
5k views

How to sense 24V AC (Thermostat) with a 5V Microcontroller

I'd like to detect thermostat events (heat, fan, ac etc) with an Arduino. I've done quite a bit of investigation but haven't found a definitive solution. Most projects I see involve controlling the ...
5
votes
3answers
16k views

If a wire is rated 10A, 120v AC. How many amps could I put through it of 13.8v DC?

I am using a wire that is rated 10Amps at 120v ACwith a car headlight and a SLA battery. About how many amps could this wire carry before getting warm or melting of DC current at 13.8volts?
5
votes
4answers
477 views

First mains-powered project - best practices?

I'm about to commence building a project that's basically a USB-controlled dimmer. I think the main components will be: Velleman K8064 voltage-controlled dimmer Phidget 1018 usb interface board ...
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 ...
5
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2answers
5k views

What is the output voltage of this 555 timer high voltage circuit?

I'm trying to calculate the theoritical output voltage of the following 555 timer high voltage circuit. It claims to output up to ...
4
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3answers
6k views

Why AC socket polarity is important?

In North America sockets and plugs design makes sure you'll be able to plug only in a certain way: (source) Why is this important for AC? Moreover, many plugs, such as cellphone chargers, are in fact ...
4
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0answers
2k views

Why DC is not used for long distance voltage transmission? (Tesla vs Edison 2015) [duplicate]

It seems this question has been marked duplicate but I believe the answers given here is much more in detail. Why we are still using AC voltage for long distance voltage transmission. As we know with ...
4
votes
2answers
5k views

Can we remove the neutral wire?

If we have the connection shown below (star connection of the secondary part of a TX), the load per each phase is equivalent (balanced load), then the vector sum of ...
4
votes
3answers
535 views

Will a 3 phase induction generator fight its own rotation?

So in a 3 phase induction generator with coils for the stator and magnets for on the rotor, I am wondering if the the current induced in the coils would create a magnetic field that would oppose the ...
3
votes
2answers
270 views

Is there a way to miniaturize cell-phone power adapter

Is there a way to miniaturize a cell-phone power adapter to be not bigger than 1-3 cubic centimeters? Is there a way to do so by using more expensive parts or something like that? I'm talking about ...