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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59 views

Arduino solar panel watt meter values reading 0's

I've been building a Arduino Watt meter for the past few weeks for a solar panel, and have successfully measured voltage and current separately. However I need to know both to calculate watts but can'...
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0answers
43 views

How to convert joules to watts for wireless sensor network?

This model for energy consumption in WSN by Heinzelman has the units joules. I want the result in watts, as far as I know there is time component for converting it to joules. How is that?
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1answer
61 views

Decreasing lumen and power usage

I have bought four of the very same led light bulbs two weeks ago. Their lightning characteristics appeared to be the same (brightness, angle, color). Two days ago I have realized that one of the ...
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0answers
17 views

Number of devices supported by one outlet [migrated]

How can I calculate how many devices I can plug in one outlet? I am living in Europe and have 220V outlets. Do I have to check the devices' volts or watts or something else entirely?
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1answer
34 views

Inverter Generator Watt Question

I'm not sure how to search this so hopefully someone will answer. I'm rigging a floundering boat for my son and want to use LED light bars on the front and sides. I want to power then with an inverter ...
5
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4answers
420 views

converting watt values over time to kWh

This is probably an elementary question, but I wanted to be sure. I have a system that reads instantaneous watts values, and stores them as "events", with a power value and a time value. According ...
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1answer
38 views

In a solar power system, when the panel is off, does the battery determine the wattage?

I am considering putting together a solar system to power my wireless router when the power goes out. I just have one question that I cannot find the answer to: Does the wattage of the solar panel ...
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4answers
83 views

What should be the watts of solar panel and battery size

I want to light one 70watt bulb for 12 hours at night time. I want to know what should be the Watts of the solar panel and how much Ah battery will I require? I searched many of the questions here ...
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1answer
89 views

Does +12V to -12V = 24V?

If a battery gives me a 5V terminal and a 0V terminal I calculate power by multiplying total current of the circuit by 5V. What if the battery has a +12V and -12V terminal I'm using to power my ...
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1answer
51 views

450mA in CK1050 rotary switch

So i bought CK1050 rotary switch i now i realized that it's rated only for 150mA 250V AC/DC on the data sheet. I need to use it with 12V DC at 450mA so will it be safe? If you think the watts it ...
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2answers
70 views

What permanent magnet motor is the best for the bike generator? How to decide about wattage?

I am new here.. I would like to build my bicycle generator with permanent magnet motor similar to this one Bicycle Power Basics Basically, I want to run my pedal cinema with a bike generator. I am ...
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votes
1answer
35 views

Can I use a power cord from a computer for an amp [closed]

I rented an amp for a keyboard but didn't take the power cord. I'm pretty sure a regular computer or computer monitor cord will fit. Is it safe? The amp says on it 175 watts. Also I have a power cord ...
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1answer
98 views

Watts and relation with A/V

I have a doubt about some numbers I'm getting in LiveWire... Can anybody explain origin of these values? I believed that watts come from Amperes x Volts, but these ciphers are driving me crazy... I ...
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2answers
80 views

What is the valid capacity ranges of Lithium Ion 18650 batteries?

I'm seeing wildly varying capacities that are seemingly fake on 18650 cells, such as these "9,800 mAh" ones on eBay, but are ~$1 / cell. However, 'genuine' cells from Panasonic and similar name ...
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votes
3answers
181 views

What does it means 100v, 10A ,100W darlington transistor?

I want to know what is the relation between (100v, 10A) and 100W in darlington transistor or actually any power device like mosfet or bjt transistor does that means I can use this transistor to drive ...
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4answers
304 views

10 Watt LED and LED Driver related question

I got a 10watt LED from Ebay but never thought that the driver and heat sinks are must-haves for this little master. When googled, I found several circuits of LED driver. But none of them are ...
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1answer
254 views

wattage consumption of three phase electric motor

i have a 5 hp motor in my factory . at load, it shows 3.5 ampere consumption ( when tested by a meter). is the consumption accurate? someone told me that 5 hp three phase motor will consume 7.5 ampere....
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1answer
179 views

On guitar amps, what is the difference between the two “watts” figures?

Disclaimer: I know nothing about electronics or guitar amps. (Actually, I do know one thing: that "wattage" is synonymous with "volume" when speaking about guitar amps and since watts are measured ...
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3answers
2k views

Why is the power consumption of electrical lamps specified in kWh/1000h?

This is the box of a LED spot I just bought. I'm wondering why the power consumption is measured in kWh/1000h and not simply in Watts. Edit: The labeling standard can be found here. (Guide for the ...
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3answers
116 views

Why are some electronic devices rated for volts and some current?

Why are some electronic devices rated for volts and some current? Isn't total wattage what matters? Most seem to be rated for amps, and Tesla famously ran hundreds of thousands of volts through ...
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2answers
90 views

Difference between incandescent/fluorescent/LED wattages?

If the numbers on the 'light output' table at the bottom of this page (here) is correct, and if I have a lamp (like this) that has a maximum wattage of 60 and takes incandescent bulbs: Does that ...
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2answers
929 views

What wattage heating element required for 500 degree Celsius oven temperature

i have 32 litres OTG oven which is of 2000 watts and can generate Max. 250 degree Celsius . 40 Litre capacity 2000 watts OTG has 2 heating elements, one at top ...
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5answers
3k views

Whats does “hr” mean among “V” and “Ah” in batteries?

I have a battery which indicates 12V25Ah/10hr. What does 10hr mean here? I guess "hr" stands for "hour". But 25Ah already means if battery is fully charged and if I load 12V 25A (=300W) to it, it ...
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1answer
60 views

Calculate VA for a given wattage [closed]

How to calculate VA given a wattage say for example 300 watts.
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1answer
55 views

Performance comparison of dual core and quad core processors with same TDP

Athlon X2 340 (dual core) and Athlon X4 740 (quad core) from AMD have same architecture and both have same TDP (65W). They also have roughly similar frequency. Does this means that at full load, the ...
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1answer
76 views

Verification on Ohm's Law?

I'm building some Heated Motorcycle Grips and I think my calculations are off. Can anyone help me verify that for 10 feet of 20 gauge Nichrome 60 wire, I have the correct Ohms, Watts, and Amps for the ...
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1answer
54 views

Solid-state lighting [closed]

Background Consider the following technologies: 100 lm/W OLED (2008, source) 303 lm/W LED (2014, source) 94 lm/W LEP (2015, source) For growing food, the preferred measurement is ...
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0answers
41 views

How to determine wattage of a resistor I found [duplicate]

In general is there a way to know what the wattage rating of a resistor is? I have a large bin of resistors of varying resistances and physical sizes. I assume size correlates to wattage as a larger ...
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1answer
185 views

Replacement Power supply for Xmas lights! [closed]

I have hit these boards as a last resort hoping someone may know a solution.... I have some xmas lights, they are a roll of 50 and each light rated at 0.06w or 0.02A. I have added 33 lights to it ...
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1answer
171 views

Resistor wattage measurement

I'm not an engineer professionally but I'm interested in. So my question is, how to recognise the wattage of a resister? And how to measure it using multimeter?
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2answers
127 views

I need to know what resistor i need for my expirement?

Im doing and expirement with electricity. Im using 120v input. I have my device i created (im not gona go into detail with what i made other than its a wireless electricity generator that im trying ...
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1answer
82 views

Amp Limitation on 120v Circuit

If an engineer needs to limit how many amps come out of a wall's circuit, how is this accomplished? I know that there is nothing preventing more than 15 amps from coming through my wall other than the ...
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2answers
65 views

What are my power requirements for my second resistor, and did I do my first's power calculation correctly for my first LED floodlight design?

I'm planning to build my very first DIY portable floodlight which will consist of a Cree XP-L V6 LED, heatsink+fan, and a 12V power source (two sets of a 8 C battery series in parallel). I plan to ...
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3answers
202 views

How much mA to charge an iPhone

I'm building an iPhone solar charger and I'm not very good with electronics but I want to know how long it would take to charge an iPhone 6 fully. The panel I'm using has: ...
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1answer
306 views

Powering a WS2812B strip

After always being interested in learning more about electronics, I figured LED-strips would be a great start. I'd like to power a 4 meter WS2812B-LED-strip (60 LEDs/m). These run on ...
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2answers
116 views

what wattage 10 ohm resistor needed for 330mA at 3.3v?

I'm pretty new to all this. Please forgive me if this is an obvious question. I am working with an ESP8266 module. They generally have a max operating current draw of somewhere around 250 mA. I ...
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1answer
62 views

Heating wire filament with low voltage high current?

Is it possible to heat nichrome wire with 0.5V 20A? what is the different between heat produced by 0.5v 20A (10watt) and 10v 1a (10watt) ?
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2answers
1k views

Does a 24V inverter consume the same amount of wattage as a 12V inverter?

Let me clarify. I know how series and parallel setups work. I know that in series the voltage adds but the current stays the same. In parallel current adds but voltage doesn't. But that doesn't ...
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1answer
316 views

AC Watts to DC Watts Calculation

Okay, so I'm new to the whole electricity field and I'm trying to get a handle on something so I apologize for any ignorance displayed here. I've purchased a new graphics card for my computer and I'm ...
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2answers
661 views

Will 0.16 amp rated fan replace a 0.3 amp fan?

I have a noisy PSU fan (400 watt Coolermaster PSU), It's 120mm and 12 volts. I have found an identical fan which is also 12v, but rated 0.16A, as opposed to the original 0.30A fan. I'm aware PSU ...
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votes
1answer
100 views

Is Ohm's law required to calculate Watts?

A buddy and I were having a conversation. One of us is convinced that Ohm's Law and Watts are the same thing. After much research I can not find anything directly pointing Ohm's Law to defining Watts, ...
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4answers
668 views

What is equivalent Resistor different Resistors put them in series or in parallel if they have a different wattage and different resistance?

What is equivalent Resistor of two this different Resistor put them in series or in parallel if they have a different wattage and different resistance? In practice somtimes we have a resistor with \$\...
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votes
1answer
89 views

how long will an 11w bulb last on 3 x 500mAh 3.7v cells [closed]

I have this question that I can't seem to figure out. I have an 11 Watt bulb and 3 500mAh 3.7V Lithium Polymer Cells. And the question is how long the bulb will last. Can anyone help me with the ...
2
votes
4answers
2k views

Higher voltage or more amps?

Im planning on building a E-Bike and have made some calculations and only need my 190rpm/V brushless motor to spin around 600 rpm to give me a good speed. So by this calculation I only need to ...
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1answer
337 views

How much power does a wrist watch use to function? [closed]

I am wondering how some watches last for a year or more on battery. How many watts does a typical battery powered watch use to move the hands?
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1answer
353 views

How does one measure the power factor?

How does one measure the power factor? $$\text{power factor}\equiv\frac{\text{power}}{|V||I|}=\frac{R}{\sqrt{R^2+(1/\omega^2C^2)}}$$ for an RC circuit driven with \$V(t)=V_0\cos{(\omega t)}\$.
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2answers
57 views

Metal Halide Bulb with Instant On?

Is it possible to produce/obtain a metal halide (MH) bulb with the possibility to turn it off and on instantly - again and again? Most MH products require 30+ minutes to restrike.. Why is this? ...
2
votes
3answers
943 views

Ribbon Cable Wattage

What is the maximum wattage (and maximum recommended wattage) for a single ribbon cable wire. I believe the wire size is 28 AWG (maybe 26, but let's call it 28 to be safe), stranded copper. The ...
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1answer
105 views

Computing Power Requirement For Solar Setup

In relation to this question: Solar power wattage requirement I'm trying to get to the math of understanding my wattage for my plan solar-setup. I would like anyone here who knew can correct me on my ...
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1answer
219 views

How Much Heat will a 1800 Watt Bulb Produce?

I plan on placing a Metal Halide 1800 watt bulb 20 inches in front of me (not exactly in front but over my head) - will this produce more heat than I can handle? Someone said the question was vague ...