The unit of measurement and SI unit for power, named after James Watt. It is equivalent to energy flow per second or Joules/Second. In electrical terms \$ W = IR = I^2 * R = V^2/R \$

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Designing/looking for a circuit board for a vaporizer [on hold]

I recently decided to look for/create a board for a vaporizer and have no idea where to start. I will probably end up programming the program in C or C++. To better explain this, I will explain the ...
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3answers
153 views

How to calculate power consumed by an electrical device in a specified amount of time?

Say for example I have a TV with "140 watts" marked on it. Does this mean the TV consumes 140W per minute? Per hour? Per day? How is the power consumed by device calculated from the device ...
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2answers
155 views

How can I communicate the difference between 2 watts of continuous power and a 2 watt capacity?

I'm trying to understand the difference between a power output in watts and a power capacity in watts, and I'm open to the possibility that I'm thinking about it all wrong. If I want to charge a ...
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3answers
196 views

Convert Watt to Ampere-hour for battery

I'm trying to find replacement batteries for my UPS, I checked my local store and they dont' have this particular model I need so I'm looking for other brand that does exactly the same. What I ...
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3answers
244 views

DC-DC Step-Down (buck) converter 5V 10A 50watt, not understand how to size the supply

I have a 5V 10A 50WATT DC step-down converter: http://www.powerstream.com/dc-24V-5V.htm I'm just not understanding how to size the power supply needed to drive this converter at max power. I have an ...
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120 views

Having trouble understanding amps, watts, voltage, and how they all work [duplicate]

I read that watts is amps multiplied by voltage. But then I read that it depends on the wattage ... what determines wattage? I thought that the outlet supplied voltage potential, and the device uses ...
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101 views

How much powerful is 600 V DC [closed]

After reading this article about various current systems for railways, I understood that there are 600V DC current lines that can move a train. So, this is an absolute beginner question. My doubt ...
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2answers
86 views

kWh per 24hours from system that uses 950W [duplicate]

my friend asked me a questions how much kWh he would get per day around if he is going to buy a power suply that is 1200W and place in the system and system would use 950W as he said ...
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1answer
77 views

Resistance and power requirements for a current-limiting resistor

I'm making my electronics project. I need answer please I need an resistor I just need to clarify and validate. Given \$V_s\$-15 V \$V_{LED}\$-3.5 V \$I_{LED}\$ - 25 mA I did: R= \$\frac{V_s - ...
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3answers
5k views

Make One Full Power XBox One Adapter from Two Underpowered Adapters

Unfortunately, as of this time, Microsoft does not sell XBox One AC adapters. XBox One adapters are almost always single voltage. I'm an expat who has bought a US XBox One and would like to use it in ...
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4answers
196 views

Why is the series resistor getting hot in this LED driving circuit?

I am trying to create the circuit below but then the resistor is getting too hot. I think is has something to do with my power source 15V, 8A. My resistor is 51 ohms, 1/4W. Any comment please... ...
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1answer
154 views

How to calculate Snubber for different load value

We are doing home automation project in that we need snubber for both resistive and inductive load. If we connect less than 5W load(Bulb) it is keep on glowing without switch on. Whether i ...
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1answer
206 views

How to convert a 10-Watt solar panel into 3v & 3 amp?

The device I use requires about 3V and 3 amps. Based on my Google research, I found out that in order to get 3V and 3 amps from a solar panel, the solar panel needs to be at least 9 watts. So let's ...
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1answer
137 views

How to use a solar panel that has 'watts' to power a battery charger that requires: 3v & 2.8 amps?

I have a battery charger that charges small batteries ( AAA & AA ). It uses an adapter that gives it 3V and 2.8 amps. I want to remove the adapter and give it solar energy instead. There are ...
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0answers
71 views

Sensitive audio detector

Here's the link to the project im currently working on : http://www.allaboutcircuits.com/vol_6/chpt_4/5.html I have a question about this transformer.I haven't been able to found an audio transformer ...
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1answer
152 views

8 ohm amp to 4 ohm speaker

I got amp which produce 2 x 30W output on 8 ohm. Is it possible for each channel to connect 60W 4ohm speaker? Is it possible to do such thing and how I can wire it?
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1answer
113 views

Combine stereo audio amplifier outputs

I got this receiver. Its output power is 2 x 30W on 8 ohms. My question is: is it possible to combine the power from these 2 channels and connect both channels to a single 60W speaker? And if it's ...
7
votes
3answers
367 views

Why don't power meters measure volt-amps

When large inductive or capacitive loads are applied, the power meter will not indicate and bill you as the electricity gets lost in the lines. Why don't power companies just charge for this?
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2answers
270 views

How should I connect four resistors to double the capacity with the same resistor? [duplicate]

I know that putting two resistors in parallel will double the wattage from the input to output, but only with half the resistance. Example Parallel Circuit: simulate this circuit – ...
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2answers
245 views

Can an LED driver operate within the whole range between min and max specs effectively, or is a load right at the max specs too large?

I am making an LED film light which I hope will output a dimmable 10000 lumens. I am looking at a driver(link at bottom). It says it is a "versatile high voltage N-channel MosFET controllers for LED ...
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2answers
200 views

Trying to understand why power equation and ohm's law equation aren't agreeing

Hobbyist EE-in-training here. I've been doing some simple problems to reinforce my knowledge of ohm's law and I've run into a snag - A stereo speaker has a resistance of 8.00 Ω. When it is ...
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1answer
113 views

efficiency problems connecting multiple solar panels

I cannot understand why doubling the amount of solar panels gives only a few percent increase in total amount of power. Here are the test results of a single 10-cell panel: Here are the test ...
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0answers
91 views

What is the rating of a DVD laser diode

I am making the "Pocket Laser Engraver" on instructables, but I need to find a replacement for the DVD drive's laser diode. (Already broke both of mine) Online I might want to get the 12x20mm 5mW ...
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2answers
545 views

Why do electric companies measure in watts, when they be measuring in joules?

1 Joule is defined as 1 Watt of power working for 1 second. When the electric bill comes, it says "you've used 5000 Watts, therefore pay us $100". However, from ...
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3k views

Does converting 12V DC to 110V AC really increase the available watts?

When designing solar panel systems for homes how do you convert the watts generated by the 12V DC solar panels to watts available in a 110/120V AC system? When I do the math it seems to defy logic. ...
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94 views

If i change the transformer on my inverter for a bigger one, will it increase the watts? [closed]

If i change the transformer on my inverter for a bigger one, will it increase the watts?
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1answer
1k views

How to calculate battery capacity required for home applications?

The issue I'm facing is calculating current draw from different household items. Like, if a fan is rated at 75 Watts, its current draw would be A = W/V so A = 75/220 and A = .34 amperes. That doesn't ...
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3answers
985 views

Interpreting the power rating of the refrigerator [closed]

My refrigerator is rated as 130W of power. I need to know how to interpret this. Does that mean if the compressor works for a whole hour then only it consumes 130W? Or is 130W the average power ...
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3answers
182 views

Get wattage (electrical power) from applicances and devices plugged in around the house

Firstly, I'm not really an electrician or an electrical guy with lots of knowledge about electronics but I'm always interested learning to it. Yesterday, I asked my wife to help me out determining ...
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4answers
493 views

Heating wire filament with low voltage / amps

Is it possible to heat either nichrome or copper wire (both 40 awg) with the following low-power delivery of 3.5 Volts, 7.4mW and 2.11mA? This is very low power delivery and we're wondering if 3 ...
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3answers
160 views

Calculate wattage of incandescent bulb

I'm trying to find out the wattage of some bulbs supplied to a company I'm working for. The product is a set of garden lights (Cheap Chinese) which is 10x small bulbs in parallel, powered by a 12Vac ...
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5answers
343 views

If watts is power and amps is current, what is volts

I know power is measured in the terms of watts, current is measured in amps, so is there an X for voltage?
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111 views

Kilowatt Hour Definition

This is a very simple question but something that I'm not able to wrap my head around. This Energy report states generated electricity. But what does "generated killowatthours" mean? I know that ...
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6answers
8k views

Does turning a lighbulb on and off repeatedly use more energy than just leaving it on for hours?

Let's say I have a 60W bulb in a lamp in my bedroom. If I kept the lamp on for 2 hours straight but the next day, I switched it on and off 10 times in intervals of 5 minutes. Which scenario would use ...
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2answers
1k views

Combining Left and Right Hook Speaker Wires Into One Speaker

So I have an mp3 player, http://dx.com/p/94814, and the mp3 player comes with a left and right speaker output. For my equipment, I only have one speaker, not two. Can I just combine the left and right ...
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1answer
1k views

Mobile/Cell Phone Power consumption?

I'm trying to work out the amount of watts my mobile phone uses and thus how much power it needs to charge back to full power. My handset is the Nokia 820 Lumia and the specs are as follows: Battery ...
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2answers
245 views

How do I find out power requirements from AC / DC specs?

I have a device with the following AC / DC specs: 100—240V, ~2 amps,50—60 Hz 24V DC @ 6.25 amps click to see device How to get power in Watts from this information? Also, for a second device: ...
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1answer
4k views

Confusion between MW and MWh

A 1MW power plant producing power constantly for 24 hours will produce 24 MWh a day. Is that right? If it is, I don't understand when it says, in ...
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5answers
450 views

Does appliance wattage differ by country, since the voltage does?

As an example, I have an AC-DC "wall wart" that specifies an input voltage of 100-230 volts and an input current of 0.3 amps. Since my mains supply is 230v: Does that mean that it uses 230*0.3=69 ...
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4answers
122 views

Looking for a better understanding of a kilowatt hour and trying to size an electricity supplier using it

I am trying to design a fuel cell that can provide enough energy for 1 day's use a maximum capacity but I am having trouble sizing the fuel cell because I need a better understanding of kilowatt ...
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2answers
2k views

What is the formula for working out the volts, amps and watts of a DC Motor?

Can anyone remind of the correct way of working out the volts amps and watts on a DC motor? I know it is something like: \$ V=I \times R \$ \$ I=\dfrac{V}{R} \$ \$ W=\dfrac{V}{I} \$ or something ...
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2answers
227 views

High wattage speaker using low wattage amplifier [closed]

If I have a 250W amplifier and I want to use a set of speakers: subwoofer x 1, 4 ohms x 1 mid-rage x 1, 4 ohms x 1 tweeters x 2, 8 ohms x 2 with a combined handeling wattage that surpasses 250W. ...
5
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2answers
542 views

Comparing A to Kwh, can it be done?

I have read this page: How to convert amps to kilowatts I often purchase electricity from a supplier to power computing equipment within a data centre. Some sell me 10 amps, some sell me 2.16 kWh. ...
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4answers
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Multiple resistors in series instead of using a single resistor has any advantage: heat produced by the resistors of diffent watts are different?

I have two doubts, requesting you to answer my doubts separately. :) 1) I need a resistance of 'X', so is it better to use a single resistor of 'X' value or multiple resistance of r1+r2+r3='X'? What ...
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2answers
2k views

Powering 10watt light bulb for 24 hours using solar power

I am a total noobi to solar power and even electricity so I appologies if I am asking a silly question. Imagine I have a 10watt light bulb which I want to leave on for 24 hours a day. Will I just ...
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3answers
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How to determine the best diameter for a cable?

In my understanding having a cable that has a too large diameter can lead to power dissipation, having one that is too small can lead to the same result. apparently the second case is much more ...
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3answers
466 views

Plugging a 65W computer power plug into a 45W step down transformer [closed]

Is it safe? Would it only charge slower, or could it damage anything? Here is the setup in more detail: I'm in Europe, where plugs are 230V. My computer was bought in the US, so it's a 110V ...
5
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5answers
541 views

Cheapest way to dissipate energy (discharge battery)

What is the cheapest way to burn a lot of energy? Say I want to burn 800W (4V, 200A). How should I do that? Ugly suggestions like: use a pot of water and a cable are welcome :) It should be easy and ...
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1answer
356 views

Impedance for Helmholtz Coil Connected to Audio Amplifier

I am trying to design a Helmholtz coil, that will have an impedance of about 2 ohms (the reason for this being that I am going to hook it up to a audio power amplifier, so to get the same wattage ...
2
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1answer
1k views

Wattage calculation for resistors in series

I need the formula for calculating resistor wattage when the resistors are in series. For example, say I have 3 1/4 watt 10 ohm resistors in series. What is the potential power dissipation for the ...