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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1answer
58 views

getting more from batteries via series connection

Let's assume I have a 100W load. If I run this load on two 2000mAh 3.7V batteries in parallel then I should get a continuous run time of 8 min 53 seconds (given the 27 amp draw). However if I were ...
0
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3answers
57 views

Which current should I use to determine the Watt?

I am making a heated blanket and I have some troubles to determine the heat that will be generated. Resistance: Let say, I use this heated cable with a resistance of 0.3 Ohms/m*. If I am using 10m ...
0
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1answer
43 views

Requirements to power 3.5kVa inverter?

How many 200 Watt solar panels do I need to power a 3.5kVa 48DCV inverter for 24 hours if the load on it is 1500 Watts and the batteries are 200Ah, 12DCV each in a country with about 6hrs of sunlight? ...
3
votes
2answers
368 views

Does a 1 watt 660nm LED put out more radiant flux than a 1 watt 630nm LED?

Given two LED chips consuming same or very similar amounts of DC power, One emitting light peaking at 630nm, The other at 660nm, In terms of output of (but light irrelevant to the sensitivity of ...
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2answers
86 views

How do I correctly estimate heat output for heater wire

This is based on a problem that came up today. During the course of this problem I realized that I wasn't so sure I understood the relationship between wattage and heat produced. In the past we did ...
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2answers
101 views

Which component cannot handle the higher wattage?

First time posting a question, so hopefully I've stated all the required details. As the title is not very specific, here is an explanation of my project. I'm making a revised version of the ...
0
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1answer
220 views

Solar panel and 120mm Computer fan

Just before I start description my question, I would like to let you know that I am new at this. I am working on a solar air heater for one of my window. I've been researching and reading up on a lot ...
11
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6answers
2k views

Is it possible to step-up the output of a laptop USB port to 12 watts?

I've got a USB device that requires 12 watts to charge. My laptop appears to output less that that. My question is: Is it possible to step-up the output of a laptop USB port to 12 watts?
0
votes
1answer
149 views

How much power does a wireless mouse use? [closed]

I have seen many answers online to how much power the USB dongle linked to a wireless mouse uses, but nothing about how much power the actual mouse draws from its batteries. What is a ball-park ...
1
vote
1answer
41 views

Selecting continuous pull type solenoid

I own a Rail track master and it needs two pull type continuous solenoids. The age of this machine is from the 1950's and both of the previous solenoids were unidentifiable. These solenoids operate ...
2
votes
2answers
106 views

On Computing Power Consumption for a GSM system

I'm a software student trying to learn about embedded systems. I would like to build a low-power system that can send his coordinates by SMS and also receive SMS. Unfortunately I'm at level zero in ...
1
vote
1answer
50 views

Flash Bulb battery depletion

Extremely simple question for you. Probably beneath all of you to answer apologies for that. My camera's flash is rated in Watt seconds. My battery is rated in mAh . If my battery can output 1000 ...
3
votes
1answer
81 views

How long can I run my camera off this battery?

I have Ultramax NP7-12 12v 7ah specifications here: http://www.batterymasters.co.uk/ProductDocs/SLAUMXNP7-12-TECH.pdf My camera consumes 1.25 watts per hour and runs at 7.8 volts but can run between ...
0
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2answers
132 views

Powering SMD 5050 strip via LM2596 DC/DC converter

I decided not to order / use the power supply typically sold with SMD 5050 kits. I heard a lot of explosion stories regarding those dodgy stuff. I want to make my own (power supply to drive SMD 5050. ...
0
votes
1answer
150 views

Why are these LEDs listed as 3W when the forward voltage is 2.4V, and forward current is 700mA?

The title of this listing says 3W: http://www.ebay.com/itm/50PCS-3W-RED-80lm-640nm-LED-Plant-Glow-Light-Emitter-with-20mm-star-base-/221518318191?pt=LH_DefaultDomain_0&hash=item3393854a6f But ...
0
votes
1answer
71 views

Using 6x58W fluorescent lamps instead of 6x55W, what could possibly go wrong? [closed]

I'm planning to buy a fluorescent photography lighting head, but the manufacturer specified it uses 6x55W lamps, but I want to use Philips Graphica 58W lamps. 3 watts more per lamp, doesn't look like ...
0
votes
2answers
128 views

What wattage solar panel required for AC 1000 watts

If my house load is 1000 Watts AC/220V, then 1000 Watts DC/12V solar panels is not enough. What wattage solar panel would be required for AC 1000 watts?
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vote
3answers
611 views

How many Watts DC are equivalent to 1,000 Watts AC? [duplicate]

How many Watts DC are equivalent to 1,000 Watts AC? For instance, my load in AC is 1,000 Watts 220V. Then, how much DC watts would an equivalent load dissipate in 12V or 24V DC system?
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vote
2answers
99 views

Watts in Solar Panels

How does the amount of watts affect a solar array? The solar array I found is 14 W, so what would I encounter if I purchased an lower/higher wattage? I'm going to purchase an array to charge my ...
0
votes
3answers
95 views

How to determine wattages on an applications note schematic?

Specifically, I refer to Fig 18 on Page 14 of this datasheet for dual supplies. Really nice, really "simple" to use 2x40W power amp I want to try out. Unfortunately, I'm a newbie and their schematic ...
2
votes
2answers
141 views

Looking for batteries to power a project I'm working on

Sorry if this is really basic, but I don't really know much about power consumption and voltage. I'm building a sensor system with a small computer with a 19V, 65W power supply, as well as a cloud ...
0
votes
0answers
49 views

Choosing a suitable power supply for a Robotzone gear motor

I'm building a project using a DC geared motor that I purchased from here: Servocity I need to know the specs of the power supply that can be used with this motor. How much current do I need? There ...
3
votes
4answers
471 views

Why is 5V DC so common? [duplicate]

I have an arduino, beaglebone black, and an arndale octa board and they all work 5V DC (albeit different amp rates). Most of my electrical sensors seem to operate around the 5V range. Why is this ...
2
votes
2answers
442 views

High voltage cable cross section

What kind of power and voltage can the cable in the photo possibly drive and why is it composed of a lot of small cables? What if the diameter of the single copper cables were a little bigger? How ...
3
votes
4answers
446 views

Voltage Divider DC 1000W for LED

I´ve done some research but not clear solutions are given to this problem, so I will post my case here in case somebody can help. Thanks in advance. I want to use a DC power supply to power up 121 ...
-4
votes
1answer
97 views

A question on Wattmeter [closed]

Wattmeter is an electric instrunment containing a resistor and an inductor.Then why are the watt-meter readings in KVA and not in KW?Is there any specific reason?
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vote
1answer
708 views

Designing/looking for a circuit board for a vaporizer [closed]

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 ...
2
votes
3answers
2k 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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vote
2answers
167 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 ...
2
votes
3answers
10k 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 ...
1
vote
3answers
585 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 ...
1
vote
3answers
318 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 ...
-3
votes
1answer
132 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 ...
-1
votes
2answers
181 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 ...
0
votes
1answer
94 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 - ...
1
vote
3answers
8k 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 ...
1
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4answers
533 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... ...
4
votes
1answer
447 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 ...
1
vote
2answers
272 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 ...
1
vote
1answer
209 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 ...
0
votes
4answers
156 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 ...
0
votes
1answer
247 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?
1
vote
1answer
350 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
660 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?
4
votes
2answers
937 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 – ...
4
votes
2answers
333 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 ...
3
votes
2answers
296 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 ...
0
votes
1answer
170 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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vote
0answers
107 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 ...
1
vote
2answers
580 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 ...